Merge commit '36bca61764984ff5395653cf8377ec5daa71b709' as 'libs/protobuf'

libs/protobuf/csharp/src/AddressBook/AddPerson.cs

@@ -0,0 +1,130 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.IO;
+
+namespace Google.Protobuf.Examples.AddressBook
+{
+    internal class AddPerson
+    {
+        /// <summary>
+        /// Builds a person based on user input
+        /// </summary>
+        private static Person PromptForAddress(TextReader input, TextWriter output)
+        {
+            Person person = new Person();
+
+            output.Write("Enter person ID: ");
+            person.Id = int.Parse(input.ReadLine());
+
+            output.Write("Enter name: ");
+            person.Name = input.ReadLine();
+
+            output.Write("Enter email address (blank for none): ");
+            string email = input.ReadLine();
+            if (email.Length > 0)
+            {
+                person.Email = email;
+            }
+
+            while (true)
+            {
+                output.Write("Enter a phone number (or leave blank to finish): ");
+                string number = input.ReadLine();
+                if (number.Length == 0)
+                {
+                    break;
+                }
+
+                Person.Types.PhoneNumber phoneNumber = new Person.Types.PhoneNumber { Number = number };
+
+                output.Write("Is this a mobile, home, or work phone? ");
+                String type = input.ReadLine();
+                switch (type)
+                {
+                    case "mobile":
+                        phoneNumber.Type = Person.Types.PhoneType.Mobile;
+                        break;
+                    case "home":
+                        phoneNumber.Type = Person.Types.PhoneType.Home;
+                        break;
+                    case "work":
+                        phoneNumber.Type = Person.Types.PhoneType.Work;
+                        break;
+                    default:
+                        output.Write("Unknown phone type. Using default.");
+                        break;
+                }
+
+                person.Phones.Add(phoneNumber);
+            }
+            return person;
+        }
+
+        /// <summary>
+        /// Entry point - loads an existing addressbook or creates a new one,
+        /// then writes it back to the file.
+        /// </summary>
+        public static int Main(string[] args)
+        {
+            if (args.Length != 1)
+            {
+                Console.Error.WriteLine("Usage:  AddPerson ADDRESS_BOOK_FILE");
+                return -1;
+            }
+
+            AddressBook addressBook;
+
+            if (File.Exists(args[0]))
+            {
+                using Stream file = File.OpenRead(args[0]);
+                addressBook = AddressBook.Parser.ParseFrom(file);
+            }
+            else
+            {
+                Console.WriteLine("{0}: File not found. Creating a new file.", args[0]);
+                addressBook = new AddressBook();
+            }
+
+            // Add an address.
+            addressBook.People.Add(PromptForAddress(Console.In, Console.Out));
+
+            // Write the new address book back to disk.
+            using (Stream output = File.OpenWrite(args[0]))
+            {
+                addressBook.WriteTo(output);
+            }
+            return 0;
+        }
+    }
+}

libs/protobuf/csharp/src/AddressBook/AddressBook.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <OutputType>Exe</OutputType>
+    <StartupObject>Google.Protobuf.Examples.AddressBook.Program</StartupObject>
+    <IsPackable>False</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Google.Protobuf\Google.Protobuf.csproj" />
+  </ItemGroup>
+
+</Project>

libs/protobuf/csharp/src/AddressBook/Addressbook.cs

@@ -0,0 +1,816 @@
+// <auto-generated>
+//     Generated by the protocol buffer compiler.  DO NOT EDIT!
+//     source: addressbook.proto
+// </auto-generated>
+#pragma warning disable 1591, 0612, 3021, 8981
+#region Designer generated code
+
+using pb = global::Google.Protobuf;
+using pbc = global::Google.Protobuf.Collections;
+using pbr = global::Google.Protobuf.Reflection;
+using scg = global::System.Collections.Generic;
+namespace Google.Protobuf.Examples.AddressBook {
+
+  /// <summary>Holder for reflection information generated from addressbook.proto</summary>
+  public static partial class AddressbookReflection {
+
+    #region Descriptor
+    /// <summary>File descriptor for addressbook.proto</summary>
+    public static pbr::FileDescriptor Descriptor {
+      get { return descriptor; }
+    }
+    private static pbr::FileDescriptor descriptor;
+
+    static AddressbookReflection() {
+      byte[] descriptorData = global::System.Convert.FromBase64String(
+          string.Concat(
+            "ChFhZGRyZXNzYm9vay5wcm90bxIIdHV0b3JpYWwaH2dvb2dsZS9wcm90b2J1",
+            "Zi90aW1lc3RhbXAucHJvdG8ihwIKBlBlcnNvbhIMCgRuYW1lGAEgASgJEgoK",
+            "AmlkGAIgASgFEg0KBWVtYWlsGAMgASgJEiwKBnBob25lcxgEIAMoCzIcLnR1",
+            "dG9yaWFsLlBlcnNvbi5QaG9uZU51bWJlchIwCgxsYXN0X3VwZGF0ZWQYBSAB",
+            "KAsyGi5nb29nbGUucHJvdG9idWYuVGltZXN0YW1wGkcKC1Bob25lTnVtYmVy",
+            "Eg4KBm51bWJlchgBIAEoCRIoCgR0eXBlGAIgASgOMhoudHV0b3JpYWwuUGVy",
+            "c29uLlBob25lVHlwZSIrCglQaG9uZVR5cGUSCgoGTU9CSUxFEAASCAoESE9N",
+            "RRABEggKBFdPUksQAiIvCgtBZGRyZXNzQm9vaxIgCgZwZW9wbGUYASADKAsy",
+            "EC50dXRvcmlhbC5QZXJzb25ClQEKG2NvbS5leGFtcGxlLnR1dG9yaWFsLnBy",
+            "b3Rvc0IRQWRkcmVzc0Jvb2tQcm90b3NQAVo6Z2l0aHViLmNvbS9wcm90b2Nv",
+            "bGJ1ZmZlcnMvcHJvdG9idWYvZXhhbXBsZXMvZ28vdHV0b3JpYWxwYqoCJEdv",
+            "b2dsZS5Qcm90b2J1Zi5FeGFtcGxlcy5BZGRyZXNzQm9va2IGcHJvdG8z"));
+      descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
+          new pbr::FileDescriptor[] { global::Google.Protobuf.WellKnownTypes.TimestampReflection.Descriptor, },
+          new pbr::GeneratedClrTypeInfo(null, null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.Examples.AddressBook.Person), global::Google.Protobuf.Examples.AddressBook.Person.Parser, new[]{ "Name", "Id", "Email", "Phones", "LastUpdated" }, null, new[]{ typeof(global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType) }, null, new pbr::GeneratedClrTypeInfo[] { new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneNumber), global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneNumber.Parser, new[]{ "Number", "Type" }, null, null, null, null)}),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.Examples.AddressBook.AddressBook), global::Google.Protobuf.Examples.AddressBook.AddressBook.Parser, new[]{ "People" }, null, null, null, null)
+          }));
+    }
+    #endregion
+
+  }
+  #region Messages
+  /// <summary>
+  /// [START messages]
+  /// </summary>
+  public sealed partial class Person : pb::IMessage<Person>
+  #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      , pb::IBufferMessage
+  #endif
+  {
+    private static readonly pb::MessageParser<Person> _parser = new pb::MessageParser<Person>(() => new Person());
+    private pb::UnknownFieldSet _unknownFields;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pb::MessageParser<Person> Parser { get { return _parser; } }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pbr::MessageDescriptor Descriptor {
+      get { return global::Google.Protobuf.Examples.AddressBook.AddressbookReflection.Descriptor.MessageTypes[0]; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    pbr::MessageDescriptor pb::IMessage.Descriptor {
+      get { return Descriptor; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public Person() {
+      OnConstruction();
+    }
+
+    partial void OnConstruction();
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public Person(Person other) : this() {
+      name_ = other.name_;
+      id_ = other.id_;
+      email_ = other.email_;
+      phones_ = other.phones_.Clone();
+      lastUpdated_ = other.lastUpdated_ != null ? other.lastUpdated_.Clone() : null;
+      _unknownFields = pb::UnknownFieldSet.Clone(other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public Person Clone() {
+      return new Person(this);
+    }
+
+    /// <summary>Field number for the "name" field.</summary>
+    public const int NameFieldNumber = 1;
+    private string name_ = "";
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public string Name {
+      get { return name_; }
+      set {
+        name_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
+      }
+    }
+
+    /// <summary>Field number for the "id" field.</summary>
+    public const int IdFieldNumber = 2;
+    private int id_;
+    /// <summary>
+    /// Unique ID number for this person.
+    /// </summary>
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int Id {
+      get { return id_; }
+      set {
+        id_ = value;
+      }
+    }
+
+    /// <summary>Field number for the "email" field.</summary>
+    public const int EmailFieldNumber = 3;
+    private string email_ = "";
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public string Email {
+      get { return email_; }
+      set {
+        email_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
+      }
+    }
+
+    /// <summary>Field number for the "phones" field.</summary>
+    public const int PhonesFieldNumber = 4;
+    private static readonly pb::FieldCodec<global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneNumber> _repeated_phones_codec
+        = pb::FieldCodec.ForMessage(34, global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneNumber.Parser);
+    private readonly pbc::RepeatedField<global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneNumber> phones_ = new pbc::RepeatedField<global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneNumber>();
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public pbc::RepeatedField<global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneNumber> Phones {
+      get { return phones_; }
+    }
+
+    /// <summary>Field number for the "last_updated" field.</summary>
+    public const int LastUpdatedFieldNumber = 5;
+    private global::Google.Protobuf.WellKnownTypes.Timestamp lastUpdated_;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public global::Google.Protobuf.WellKnownTypes.Timestamp LastUpdated {
+      get { return lastUpdated_; }
+      set {
+        lastUpdated_ = value;
+      }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override bool Equals(object other) {
+      return Equals(other as Person);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public bool Equals(Person other) {
+      if (ReferenceEquals(other, null)) {
+        return false;
+      }
+      if (ReferenceEquals(other, this)) {
+        return true;
+      }
+      if (Name != other.Name) return false;
+      if (Id != other.Id) return false;
+      if (Email != other.Email) return false;
+      if(!phones_.Equals(other.phones_)) return false;
+      if (!object.Equals(LastUpdated, other.LastUpdated)) return false;
+      return Equals(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override int GetHashCode() {
+      int hash = 1;
+      if (Name.Length != 0) hash ^= Name.GetHashCode();
+      if (Id != 0) hash ^= Id.GetHashCode();
+      if (Email.Length != 0) hash ^= Email.GetHashCode();
+      hash ^= phones_.GetHashCode();
+      if (lastUpdated_ != null) hash ^= LastUpdated.GetHashCode();
+      if (_unknownFields != null) {
+        hash ^= _unknownFields.GetHashCode();
+      }
+      return hash;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override string ToString() {
+      return pb::JsonFormatter.ToDiagnosticString(this);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void WriteTo(pb::CodedOutputStream output) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      output.WriteRawMessage(this);
+    #else
+      if (Name.Length != 0) {
+        output.WriteRawTag(10);
+        output.WriteString(Name);
+      }
+      if (Id != 0) {
+        output.WriteRawTag(16);
+        output.WriteInt32(Id);
+      }
+      if (Email.Length != 0) {
+        output.WriteRawTag(26);
+        output.WriteString(Email);
+      }
+      phones_.WriteTo(output, _repeated_phones_codec);
+      if (lastUpdated_ != null) {
+        output.WriteRawTag(42);
+        output.WriteMessage(LastUpdated);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(output);
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalWriteTo(ref pb::WriteContext output) {
+      if (Name.Length != 0) {
+        output.WriteRawTag(10);
+        output.WriteString(Name);
+      }
+      if (Id != 0) {
+        output.WriteRawTag(16);
+        output.WriteInt32(Id);
+      }
+      if (Email.Length != 0) {
+        output.WriteRawTag(26);
+        output.WriteString(Email);
+      }
+      phones_.WriteTo(ref output, _repeated_phones_codec);
+      if (lastUpdated_ != null) {
+        output.WriteRawTag(42);
+        output.WriteMessage(LastUpdated);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(ref output);
+      }
+    }
+    #endif
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int CalculateSize() {
+      int size = 0;
+      if (Name.Length != 0) {
+        size += 1 + pb::CodedOutputStream.ComputeStringSize(Name);
+      }
+      if (Id != 0) {
+        size += 1 + pb::CodedOutputStream.ComputeInt32Size(Id);
+      }
+      if (Email.Length != 0) {
+        size += 1 + pb::CodedOutputStream.ComputeStringSize(Email);
+      }
+      size += phones_.CalculateSize(_repeated_phones_codec);
+      if (lastUpdated_ != null) {
+        size += 1 + pb::CodedOutputStream.ComputeMessageSize(LastUpdated);
+      }
+      if (_unknownFields != null) {
+        size += _unknownFields.CalculateSize();
+      }
+      return size;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(Person other) {
+      if (other == null) {
+        return;
+      }
+      if (other.Name.Length != 0) {
+        Name = other.Name;
+      }
+      if (other.Id != 0) {
+        Id = other.Id;
+      }
+      if (other.Email.Length != 0) {
+        Email = other.Email;
+      }
+      phones_.Add(other.phones_);
+      if (other.lastUpdated_ != null) {
+        if (lastUpdated_ == null) {
+          LastUpdated = new global::Google.Protobuf.WellKnownTypes.Timestamp();
+        }
+        LastUpdated.MergeFrom(other.LastUpdated);
+      }
+      _unknownFields = pb::UnknownFieldSet.MergeFrom(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(pb::CodedInputStream input) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      input.ReadRawMessage(this);
+    #else
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
+            break;
+          case 10: {
+            Name = input.ReadString();
+            break;
+          }
+          case 16: {
+            Id = input.ReadInt32();
+            break;
+          }
+          case 26: {
+            Email = input.ReadString();
+            break;
+          }
+          case 34: {
+            phones_.AddEntriesFrom(input, _repeated_phones_codec);
+            break;
+          }
+          case 42: {
+            if (lastUpdated_ == null) {
+              LastUpdated = new global::Google.Protobuf.WellKnownTypes.Timestamp();
+            }
+            input.ReadMessage(LastUpdated);
+            break;
+          }
+        }
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalMergeFrom(ref pb::ParseContext input) {
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, ref input);
+            break;
+          case 10: {
+            Name = input.ReadString();
+            break;
+          }
+          case 16: {
+            Id = input.ReadInt32();
+            break;
+          }
+          case 26: {
+            Email = input.ReadString();
+            break;
+          }
+          case 34: {
+            phones_.AddEntriesFrom(ref input, _repeated_phones_codec);
+            break;
+          }
+          case 42: {
+            if (lastUpdated_ == null) {
+              LastUpdated = new global::Google.Protobuf.WellKnownTypes.Timestamp();
+            }
+            input.ReadMessage(LastUpdated);
+            break;
+          }
+        }
+      }
+    }
+    #endif
+
+    #region Nested types
+    /// <summary>Container for nested types declared in the Person message type.</summary>
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static partial class Types {
+      public enum PhoneType {
+        [pbr::OriginalName("MOBILE")] Mobile = 0,
+        [pbr::OriginalName("HOME")] Home = 1,
+        [pbr::OriginalName("WORK")] Work = 2,
+      }
+
+      public sealed partial class PhoneNumber : pb::IMessage<PhoneNumber>
+      #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+          , pb::IBufferMessage
+      #endif
+      {
+        private static readonly pb::MessageParser<PhoneNumber> _parser = new pb::MessageParser<PhoneNumber>(() => new PhoneNumber());
+        private pb::UnknownFieldSet _unknownFields;
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public static pb::MessageParser<PhoneNumber> Parser { get { return _parser; } }
+
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public static pbr::MessageDescriptor Descriptor {
+          get { return global::Google.Protobuf.Examples.AddressBook.Person.Descriptor.NestedTypes[0]; }
+        }
+
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        pbr::MessageDescriptor pb::IMessage.Descriptor {
+          get { return Descriptor; }
+        }
+
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public PhoneNumber() {
+          OnConstruction();
+        }
+
+        partial void OnConstruction();
+
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public PhoneNumber(PhoneNumber other) : this() {
+          number_ = other.number_;
+          type_ = other.type_;
+          _unknownFields = pb::UnknownFieldSet.Clone(other._unknownFields);
+        }
+
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public PhoneNumber Clone() {
+          return new PhoneNumber(this);
+        }
+
+        /// <summary>Field number for the "number" field.</summary>
+        public const int NumberFieldNumber = 1;
+        private string number_ = "";
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public string Number {
+          get { return number_; }
+          set {
+            number_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
+          }
+        }
+
+        /// <summary>Field number for the "type" field.</summary>
+        public const int TypeFieldNumber = 2;
+        private global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType type_ = global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType.Mobile;
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType Type {
+          get { return type_; }
+          set {
+            type_ = value;
+          }
+        }
+
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public override bool Equals(object other) {
+          return Equals(other as PhoneNumber);
+        }
+
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public bool Equals(PhoneNumber other) {
+          if (ReferenceEquals(other, null)) {
+            return false;
+          }
+          if (ReferenceEquals(other, this)) {
+            return true;
+          }
+          if (Number != other.Number) return false;
+          if (Type != other.Type) return false;
+          return Equals(_unknownFields, other._unknownFields);
+        }
+
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public override int GetHashCode() {
+          int hash = 1;
+          if (Number.Length != 0) hash ^= Number.GetHashCode();
+          if (Type != global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType.Mobile) hash ^= Type.GetHashCode();
+          if (_unknownFields != null) {
+            hash ^= _unknownFields.GetHashCode();
+          }
+          return hash;
+        }
+
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public override string ToString() {
+          return pb::JsonFormatter.ToDiagnosticString(this);
+        }
+
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public void WriteTo(pb::CodedOutputStream output) {
+        #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+          output.WriteRawMessage(this);
+        #else
+          if (Number.Length != 0) {
+            output.WriteRawTag(10);
+            output.WriteString(Number);
+          }
+          if (Type != global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType.Mobile) {
+            output.WriteRawTag(16);
+            output.WriteEnum((int) Type);
+          }
+          if (_unknownFields != null) {
+            _unknownFields.WriteTo(output);
+          }
+        #endif
+        }
+
+        #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        void pb::IBufferMessage.InternalWriteTo(ref pb::WriteContext output) {
+          if (Number.Length != 0) {
+            output.WriteRawTag(10);
+            output.WriteString(Number);
+          }
+          if (Type != global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType.Mobile) {
+            output.WriteRawTag(16);
+            output.WriteEnum((int) Type);
+          }
+          if (_unknownFields != null) {
+            _unknownFields.WriteTo(ref output);
+          }
+        }
+        #endif
+
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public int CalculateSize() {
+          int size = 0;
+          if (Number.Length != 0) {
+            size += 1 + pb::CodedOutputStream.ComputeStringSize(Number);
+          }
+          if (Type != global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType.Mobile) {
+            size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Type);
+          }
+          if (_unknownFields != null) {
+            size += _unknownFields.CalculateSize();
+          }
+          return size;
+        }
+
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public void MergeFrom(PhoneNumber other) {
+          if (other == null) {
+            return;
+          }
+          if (other.Number.Length != 0) {
+            Number = other.Number;
+          }
+          if (other.Type != global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType.Mobile) {
+            Type = other.Type;
+          }
+          _unknownFields = pb::UnknownFieldSet.MergeFrom(_unknownFields, other._unknownFields);
+        }
+
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        public void MergeFrom(pb::CodedInputStream input) {
+        #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+          input.ReadRawMessage(this);
+        #else
+          uint tag;
+          while ((tag = input.ReadTag()) != 0) {
+            switch(tag) {
+              default:
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
+                break;
+              case 10: {
+                Number = input.ReadString();
+                break;
+              }
+              case 16: {
+                Type = (global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType) input.ReadEnum();
+                break;
+              }
+            }
+          }
+        #endif
+        }
+
+        #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+        [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+        void pb::IBufferMessage.InternalMergeFrom(ref pb::ParseContext input) {
+          uint tag;
+          while ((tag = input.ReadTag()) != 0) {
+            switch(tag) {
+              default:
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, ref input);
+                break;
+              case 10: {
+                Number = input.ReadString();
+                break;
+              }
+              case 16: {
+                Type = (global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType) input.ReadEnum();
+                break;
+              }
+            }
+          }
+        }
+        #endif
+
+      }
+
+    }
+    #endregion
+
+  }
+
+  /// <summary>
+  /// Our address book file is just one of these.
+  /// </summary>
+  public sealed partial class AddressBook : pb::IMessage<AddressBook>
+  #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      , pb::IBufferMessage
+  #endif
+  {
+    private static readonly pb::MessageParser<AddressBook> _parser = new pb::MessageParser<AddressBook>(() => new AddressBook());
+    private pb::UnknownFieldSet _unknownFields;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pb::MessageParser<AddressBook> Parser { get { return _parser; } }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pbr::MessageDescriptor Descriptor {
+      get { return global::Google.Protobuf.Examples.AddressBook.AddressbookReflection.Descriptor.MessageTypes[1]; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    pbr::MessageDescriptor pb::IMessage.Descriptor {
+      get { return Descriptor; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public AddressBook() {
+      OnConstruction();
+    }
+
+    partial void OnConstruction();
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public AddressBook(AddressBook other) : this() {
+      people_ = other.people_.Clone();
+      _unknownFields = pb::UnknownFieldSet.Clone(other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public AddressBook Clone() {
+      return new AddressBook(this);
+    }
+
+    /// <summary>Field number for the "people" field.</summary>
+    public const int PeopleFieldNumber = 1;
+    private static readonly pb::FieldCodec<global::Google.Protobuf.Examples.AddressBook.Person> _repeated_people_codec
+        = pb::FieldCodec.ForMessage(10, global::Google.Protobuf.Examples.AddressBook.Person.Parser);
+    private readonly pbc::RepeatedField<global::Google.Protobuf.Examples.AddressBook.Person> people_ = new pbc::RepeatedField<global::Google.Protobuf.Examples.AddressBook.Person>();
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public pbc::RepeatedField<global::Google.Protobuf.Examples.AddressBook.Person> People {
+      get { return people_; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override bool Equals(object other) {
+      return Equals(other as AddressBook);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public bool Equals(AddressBook other) {
+      if (ReferenceEquals(other, null)) {
+        return false;
+      }
+      if (ReferenceEquals(other, this)) {
+        return true;
+      }
+      if(!people_.Equals(other.people_)) return false;
+      return Equals(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override int GetHashCode() {
+      int hash = 1;
+      hash ^= people_.GetHashCode();
+      if (_unknownFields != null) {
+        hash ^= _unknownFields.GetHashCode();
+      }
+      return hash;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override string ToString() {
+      return pb::JsonFormatter.ToDiagnosticString(this);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void WriteTo(pb::CodedOutputStream output) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      output.WriteRawMessage(this);
+    #else
+      people_.WriteTo(output, _repeated_people_codec);
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(output);
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalWriteTo(ref pb::WriteContext output) {
+      people_.WriteTo(ref output, _repeated_people_codec);
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(ref output);
+      }
+    }
+    #endif
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int CalculateSize() {
+      int size = 0;
+      size += people_.CalculateSize(_repeated_people_codec);
+      if (_unknownFields != null) {
+        size += _unknownFields.CalculateSize();
+      }
+      return size;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(AddressBook other) {
+      if (other == null) {
+        return;
+      }
+      people_.Add(other.people_);
+      _unknownFields = pb::UnknownFieldSet.MergeFrom(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(pb::CodedInputStream input) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      input.ReadRawMessage(this);
+    #else
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
+            break;
+          case 10: {
+            people_.AddEntriesFrom(input, _repeated_people_codec);
+            break;
+          }
+        }
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalMergeFrom(ref pb::ParseContext input) {
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, ref input);
+            break;
+          case 10: {
+            people_.AddEntriesFrom(ref input, _repeated_people_codec);
+            break;
+          }
+        }
+      }
+    }
+    #endif
+
+  }
+
+  #endregion
+
+}
+
+#endregion Designer generated code

libs/protobuf/csharp/src/AddressBook/ListPeople.cs

@@ -0,0 +1,99 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.IO;
+
+namespace Google.Protobuf.Examples.AddressBook
+{
+    internal class ListPeople
+    {
+        /// <summary>
+        /// Iterates though all people in the AddressBook and prints info about them.
+        /// </summary>
+        private static void Print(AddressBook addressBook)
+        {
+            foreach (Person person in addressBook.People)
+            {
+                Console.WriteLine("Person ID: {0}", person.Id);
+                Console.WriteLine("  Name: {0}", person.Name);
+                if (person.Email != "")
+                {
+                    Console.WriteLine("  E-mail address: {0}", person.Email);
+                }
+
+                foreach (Person.Types.PhoneNumber phoneNumber in person.Phones)
+                {
+                    switch (phoneNumber.Type)
+                    {
+                        case Person.Types.PhoneType.Mobile:
+                            Console.Write("  Mobile phone #: ");
+                            break;
+                        case Person.Types.PhoneType.Home:
+                            Console.Write("  Home phone #: ");
+                            break;
+                        case Person.Types.PhoneType.Work:
+                            Console.Write("  Work phone #: ");
+                            break;
+                    }
+                    Console.WriteLine(phoneNumber.Number);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Entry point - loads the addressbook and then displays it.
+        /// </summary>
+        public static int Main(string[] args)
+        {
+            if (args.Length != 1)
+            {
+                Console.Error.WriteLine("Usage:  ListPeople ADDRESS_BOOK_FILE");
+                return 1;
+            }
+
+            if (!File.Exists(args[0]))
+            {
+                Console.WriteLine("{0} doesn't exist. Add a person to create the file first.", args[0]);
+                return 0;
+            }
+
+            // Read the existing address book.
+            using (Stream stream = File.OpenRead(args[0]))
+            {
+                AddressBook addressBook = AddressBook.Parser.ParseFrom(stream);
+                Print(addressBook);
+            }
+            return 0;
+        }
+    }
+}

libs/protobuf/csharp/src/AddressBook/Program.cs

@@ -0,0 +1,95 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+
+namespace Google.Protobuf.Examples.AddressBook
+{
+    /// <summary>
+    /// Entry point. Repeatedly prompts user for an action to take, delegating actual behaviour
+    /// to individual actions. Each action has its own Main method, so that it can be used as an
+    /// individual complete program.
+    /// </summary>
+    internal class Program
+    {
+        private static int Main(string[] args)
+        {
+            if (args.Length > 1)
+            {
+                Console.Error.WriteLine("Usage: AddressBook [file]");
+                Console.Error.WriteLine("If the filename isn't specified, \"addressbook.data\" is used instead.");
+                return 1;
+            }
+            string addressBookFile = args.Length > 0 ? args[0] : "addressbook.data";
+
+            bool stopping = false;
+            while (!stopping)
+            {
+                Console.WriteLine("Options:");
+                Console.WriteLine("  L: List contents");
+                Console.WriteLine("  A: Add new person");
+                Console.WriteLine("  Q: Quit");
+                Console.Write("Action? ");
+                Console.Out.Flush();
+                char choice = Console.ReadKey().KeyChar;
+                Console.WriteLine();
+                try
+                {
+                    switch (choice)
+                    {
+                        case 'A':
+                        case 'a':
+                            AddPerson.Main(new string[] {addressBookFile});
+                            break;
+                        case 'L':
+                        case 'l':
+                            ListPeople.Main(new string[] {addressBookFile});
+                            break;
+                        case 'Q':
+                        case 'q':
+                            stopping = true;
+                            break;
+                        default:
+                            Console.WriteLine("Unknown option: {0}", choice);
+                            break;
+                    }
+                }
+                catch (Exception e)
+                {
+                    Console.WriteLine("Exception executing action: {0}", e);
+                }
+                Console.WriteLine();
+            }
+            return 0;
+        }
+    }
+}

libs/protobuf/csharp/src/AddressBook/SampleUsage.cs

@@ -0,0 +1,73 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+    
+using System;
+using System.IO;
+
+namespace Google.Protobuf.Examples.AddressBook
+{
+    internal class SampleUsage
+    {
+        private static void Main()
+        {
+            byte[] bytes;
+            // Create a new person
+            Person person = new Person
+            {
+                Id = 1,
+                Name = "Foo",
+                Email = "foo@bar",
+                Phones = { new Person.Types.PhoneNumber { Number = "555-1212" } }
+            };
+            using (MemoryStream stream = new MemoryStream())
+            {
+                // Save the person to a stream
+                person.WriteTo(stream);
+                bytes = stream.ToArray();
+            }
+            Person copy = Person.Parser.ParseFrom(bytes);
+
+            AddressBook book = new AddressBook
+            {
+                People = { copy }
+            };
+            bytes = book.ToByteArray();
+            // And read the address book back again
+            AddressBook restored = AddressBook.Parser.ParseFrom(bytes);
+            // The message performs a deep-comparison on equality:
+            if (restored.People.Count != 1 || !person.Equals(restored.People[0]))
+            {
+                throw new Exception("There is a bad person in here!");
+            }
+        }
+    }
+}

libs/protobuf/csharp/src/Directory.Build.props

@@ -0,0 +1,7 @@
+<Project>
+
+  <PropertyGroup>
+    <LangVersion>10.0</LangVersion>
+  </PropertyGroup>
+
+</Project>

libs/protobuf/csharp/src/Google.Protobuf.Conformance/BUILD.bazel

@@ -0,0 +1,97 @@
+load("//build_defs:internal_shell.bzl", "inline_sh_binary")
+load("@rules_pkg//:mappings.bzl", "pkg_files", "strip_prefix")
+
+inline_sh_binary(
+    name = "build_conformance_test",
+    srcs = ["Google.Protobuf.Conformance.csproj"],
+    cmd = "dotnet build -c Release $(SRCS)",
+    visibility = ["//visibility:private"],
+)
+
+CONFORMANCE_DEPS = [
+    "Google.Protobuf.dll",
+    "Google.Protobuf.Conformance.deps.json",
+    "Google.Protobuf.Conformance.pdb",
+    "Google.Protobuf.Conformance.runtimeconfig.json",
+    "Google.Protobuf.Test.dll",
+    "Google.Protobuf.Test.TestProtos.dll",
+    "Microsoft.TestPlatform.CommunicationUtilities.dll",
+    "Microsoft.TestPlatform.CoreUtilities.dll",
+    "Microsoft.TestPlatform.CrossPlatEngine.dll",
+    "Microsoft.TestPlatform.PlatformAbstractions.dll",
+    "Microsoft.TestPlatform.Utilities.dll",
+    "Microsoft.VisualStudio.CodeCoverage.Shim.dll",
+    "Microsoft.VisualStudio.TestPlatform.Common.dll",
+    "Microsoft.VisualStudio.TestPlatform.ObjectModel.dll",
+    "NUnit3.TestAdapter.dll",
+    "Newtonsoft.Json.dll",
+    "NuGet.Frameworks.dll",
+    "nunit.engine.api.dll",
+    "nunit.engine.core.dll",
+    "nunit.engine.dll",
+    "nunit.framework.dll",
+    "testcentric.engine.metadata.dll",
+    "testhost.dll",
+]
+
+filegroup(
+    name = "srcs",
+    srcs = [
+        "Conformance.cs",
+        "Program.cs",
+        "Google.Protobuf.Conformance.csproj",
+    ],
+    visibility = [
+        "//csharp:__subpackages__",
+    ],
+)
+
+genrule(
+    name = "package_conformance_test",
+    srcs = [
+        "Program.cs",
+        "Google.Protobuf.Conformance.csproj",
+        "//conformance:conformance_csharp_proto",
+        "//csharp:srcs",
+    ],
+    visibility = ["//visibility:private"],
+    tools = [":build_conformance_test"],
+    outs = CONFORMANCE_DEPS + ["Google.Protobuf.Conformance.dll"],
+    cmd = """
+        SRCDIR=$$(dirname $(location :Program.cs))
+        cp $(location //conformance:conformance_csharp_proto) $$SRCDIR
+        DOTNET_CLI_HOME=/tmp ./$(location :build_conformance_test)
+        cp -r $$SRCDIR/bin/Release/netcoreapp3.1/* $(RULEDIR)
+    """,
+)
+
+filegroup(
+    name = "conformance_dll",
+    srcs = ["Google.Protobuf.Conformance.dll"],
+    data = [":package_conformance_test"],
+    visibility = ["//conformance:__subpackages__"],
+)
+
+filegroup(
+    name = "conformance_runfiles",
+    srcs = CONFORMANCE_DEPS,
+    data = [":package_conformance_test"],
+    visibility = ["//conformance:__subpackages__"],
+)
+
+################################################################################
+# Distribution files
+################################################################################
+
+pkg_files(
+    name = "dist_files",
+    srcs = [
+        "BUILD.bazel",
+        "Google.Protobuf.Conformance.csproj",
+        "Conformance.cs",
+        "Program.cs",
+    ],
+    strip_prefix = strip_prefix.from_root(""),
+    visibility = ["//csharp:__pkg__"],
+)
+

libs/protobuf/csharp/src/Google.Protobuf.Conformance/Google.Protobuf.Conformance.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <OutputType>Exe</OutputType>
+    <IsPackable>False</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Google.Protobuf\Google.Protobuf.csproj" />
+    <ProjectReference Include="..\Google.Protobuf.Test\Google.Protobuf.Test.csproj" />
+  </ItemGroup>
+
+</Project>

libs/protobuf/csharp/src/Google.Protobuf.Conformance/Program.cs

@@ -0,0 +1,168 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using Conformance;
+using Google.Protobuf.Reflection;
+using System;
+using System.IO;
+
+namespace Google.Protobuf.Conformance
+{
+    /// <summary>
+    /// Conformance tests. The test runner will provide JSON or proto data on stdin,
+    /// and this program will produce its output on stdout.
+    /// </summary>
+    class Program
+    {
+        private static void Main()
+        {
+            // This way we get the binary streams instead of readers/writers.
+            var input = new BinaryReader(Console.OpenStandardInput());
+            var output = new BinaryWriter(Console.OpenStandardOutput());
+            var typeRegistry = TypeRegistry.FromMessages(
+                ProtobufTestMessages.Proto3.TestAllTypesProto3.Descriptor,
+                ProtobufTestMessages.Proto2.TestAllTypesProto2.Descriptor);
+
+            int count = 0;
+            while (RunTest(input, output, typeRegistry))
+            {
+                count++;
+            }
+            Console.Error.WriteLine("Received EOF after {0} tests", count);
+        }
+
+        private static bool RunTest(BinaryReader input, BinaryWriter output, TypeRegistry typeRegistry)
+        {
+            int? size = ReadInt32(input);
+            if (size == null)
+            {
+                return false;
+            }
+            byte[] inputData = input.ReadBytes(size.Value);
+            if (inputData.Length != size.Value)
+            {
+                throw new EndOfStreamException("Read " + inputData.Length + " bytes of data when expecting " + size);
+            }
+            ConformanceRequest request = ConformanceRequest.Parser.ParseFrom(inputData);
+            ConformanceResponse response = PerformRequest(request, typeRegistry);
+            byte[] outputData = response.ToByteArray();
+            output.Write(outputData.Length);
+            output.Write(outputData);
+            // Ready for another test...
+            return true;
+        }
+
+        private static ConformanceResponse PerformRequest(ConformanceRequest request, TypeRegistry typeRegistry)
+        {
+            ExtensionRegistry proto2ExtensionRegistry = new ExtensionRegistry
+            {
+                ProtobufTestMessages.Proto2.TestMessagesProto2Extensions.ExtensionInt32,
+                ProtobufTestMessages.Proto2.TestAllTypesProto2.Types.MessageSetCorrectExtension1.Extensions.MessageSetExtension,
+                ProtobufTestMessages.Proto2.TestAllTypesProto2.Types.MessageSetCorrectExtension2.Extensions.MessageSetExtension
+            };
+            IMessage message;
+            try
+            {
+                switch (request.PayloadCase)
+                {
+                    case ConformanceRequest.PayloadOneofCase.JsonPayload:
+                        if (request.TestCategory == global::Conformance.TestCategory.JsonIgnoreUnknownParsingTest)
+                        {
+                            return new ConformanceResponse { Skipped = "CSharp doesn't support skipping unknown fields in json parsing." };
+                        }
+                        var parser = new JsonParser(new JsonParser.Settings(20, typeRegistry));
+                        message = request.MessageType switch
+                        {
+                            "protobuf_test_messages.proto3.TestAllTypesProto3" => parser.Parse<ProtobufTestMessages.Proto3.TestAllTypesProto3>(request.JsonPayload),
+                            "protobuf_test_messages.proto2.TestAllTypesProto2" => parser.Parse<ProtobufTestMessages.Proto2.TestAllTypesProto2>(request.JsonPayload),
+                            _ => throw new Exception($" Protobuf request doesn't have specific payload type ({request.MessageType})"),
+                        };
+                        break;
+                    case ConformanceRequest.PayloadOneofCase.ProtobufPayload:
+                        message = request.MessageType switch
+                        {
+                            "protobuf_test_messages.proto3.TestAllTypesProto3" => ProtobufTestMessages.Proto3.TestAllTypesProto3.Parser.ParseFrom(request.ProtobufPayload),
+                            "protobuf_test_messages.proto2.TestAllTypesProto2" => ProtobufTestMessages.Proto2.TestAllTypesProto2.Parser
+                                                                .WithExtensionRegistry(proto2ExtensionRegistry)
+                                                                .ParseFrom(request.ProtobufPayload),
+                            _ => throw new Exception($" Protobuf request doesn't have specific payload type ({request.MessageType})"),
+                        };
+                        break;
+					case ConformanceRequest.PayloadOneofCase.TextPayload:
+						return new ConformanceResponse { Skipped = "CSharp doesn't support text format" };
+                    default:
+                        throw new Exception("Unsupported request payload: " + request.PayloadCase);
+                }
+            }
+            catch (InvalidProtocolBufferException e)
+            {
+                return new ConformanceResponse { ParseError = e.Message };
+            }
+            catch (InvalidJsonException e)
+            {
+                return new ConformanceResponse { ParseError = e.Message };
+            }
+            try
+            {
+                switch (request.RequestedOutputFormat)
+                {
+                    case global::Conformance.WireFormat.Json:
+                        var formatter = new JsonFormatter(new JsonFormatter.Settings(false, typeRegistry));
+                        return new ConformanceResponse { JsonPayload = formatter.Format(message) };
+                    case global::Conformance.WireFormat.Protobuf:
+                        return new ConformanceResponse { ProtobufPayload = message.ToByteString() };
+                    default:
+                        throw new Exception("Unsupported request output format: " + request.RequestedOutputFormat);
+                }
+            }
+            catch (InvalidOperationException e)
+            {
+                return new ConformanceResponse { SerializeError = e.Message };
+            }
+        }
+
+        private static int? ReadInt32(BinaryReader input)
+        {
+            byte[] bytes = input.ReadBytes(4);
+            if (bytes.Length == 0)
+            {
+                // Cleanly reached the end of the stream
+                return null;
+            }
+            if (bytes.Length != 4)
+            {
+                throw new EndOfStreamException("Read " + bytes.Length + " bytes of size when expecting 4");
+            }
+            return bytes[0] | (bytes[1] << 8) | (bytes[2] << 16) | (bytes[3] << 24);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.JsonDump/Google.Protobuf.JsonDump.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <OutputType>Exe</OutputType>
+    <IsPackable>False</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Google.Protobuf\Google.Protobuf.csproj" />
+  </ItemGroup>
+
+</Project>

libs/protobuf/csharp/src/Google.Protobuf.JsonDump/Program.cs

@@ -0,0 +1,73 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.IO;
+using System.Reflection;
+
+namespace Google.Protobuf.ProtoDump
+{
+    /// <summary>
+    /// Small utility to load a binary message and dump it in JSON format.
+    /// </summary>
+    internal class Program
+    {
+        private static int Main(string[] args)
+        {
+            if (args.Length != 2)
+            {
+                Console.Error.WriteLine("Usage: Google.Protobuf.JsonDump <descriptor type name> <input data>");
+                Console.Error.WriteLine("The descriptor type name is the fully-qualified message name,");
+                Console.Error.WriteLine("including assembly e.g. ProjectNamespace.Message,Company.Project");
+                return 1;
+            }
+            Type type = Type.GetType(args[0]);
+            if (type == null)
+            {
+                Console.Error.WriteLine("Unable to load type {0}.", args[0]);
+                return 1;
+            }
+            if (!typeof(IMessage).GetTypeInfo().IsAssignableFrom(type))
+            {
+                Console.Error.WriteLine("Type {0} doesn't implement IMessage.", args[0]);
+                return 1;
+            }
+            IMessage message = (IMessage) Activator.CreateInstance(type);
+            using (var input = File.OpenRead(args[1]))
+            {
+                message.MergeFrom(input);
+            }
+            Console.WriteLine(message);
+            return 0;
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test.TestProtos/ForeignMessagePartial.cs

@@ -0,0 +1,45 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2016 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+namespace Google.Protobuf.TestProtos
+{
+    /// <summary>
+    /// A message with custom diagnostics (to test that they work).
+    /// </summary>
+    public partial class ForeignMessage : ICustomDiagnosticMessage
+    {
+        public string ToDiagnosticString()
+        {
+            return string.Format("{{ \"c\": {0}, \"@cInHex\": \"{0:x}\" }}", C);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test.TestProtos/Google.Protobuf.Test.TestProtos.csproj

@@ -0,0 +1,25 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <!--
+    This TestProtos project is kept separate from the original test project for many reasons.
+    It allows us to make sure code can compile on a separate compiler version, different frameworks,
+    and without the internal visibility from the test project (all of which have caused issues in the past).
+  -->
+  <PropertyGroup>
+    <TargetFrameworks>net462;netstandard1.1;netstandard2.0</TargetFrameworks>
+    <LangVersion>10.0</LangVersion>
+    <AssemblyOriginatorKeyFile>../../keys/Google.Protobuf.snk</AssemblyOriginatorKeyFile>
+    <SignAssembly>true</SignAssembly>
+    <IsPackable>False</IsPackable>
+  </PropertyGroup>
+
+  <!-- Needed for the net45 build to work on Unix. See https://github.com/dotnet/designs/pull/33 -->
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.2" PrivateAssets="All" />
+  </ItemGroup>
+  
+  <ItemGroup>
+    <ProjectReference Include="..\Google.Protobuf\Google.Protobuf.csproj" />
+  </ItemGroup>
+
+</Project>

libs/protobuf/csharp/src/Google.Protobuf.Test.TestProtos/OldExtensions1.cs

@@ -0,0 +1,148 @@
+// <auto-generated>
+//     Generated by the protocol buffer compiler.  DO NOT EDIT!
+//     source: old_extensions1.proto
+// </auto-generated>
+#pragma warning disable 1591, 0612, 3021
+#region Designer generated code
+
+using pb = global::Google.Protobuf;
+using pbc = global::Google.Protobuf.Collections;
+using pbr = global::Google.Protobuf.Reflection;
+using scg = global::System.Collections.Generic;
+namespace Google.Protobuf.TestProtos.OldGenerator {
+
+  /// <summary>Holder for reflection information generated from old_extensions1.proto</summary>
+  public static partial class OldExtensions1Reflection {
+
+    #region Descriptor
+    /// <summary>File descriptor for old_extensions1.proto</summary>
+    public static pbr::FileDescriptor Descriptor {
+      get { return descriptor; }
+    }
+    private static pbr::FileDescriptor descriptor;
+
+    static OldExtensions1Reflection() {
+      byte[] descriptorData = global::System.Convert.FromBase64String(
+          string.Concat(
+            "ChVvbGRfZXh0ZW5zaW9uczEucHJvdG8aFW9sZF9leHRlbnNpb25zMi5wcm90",
+            "byINCgtUZXN0TWVzc2FnZUIqqgInR29vZ2xlLlByb3RvYnVmLlRlc3RQcm90",
+            "b3MuT2xkR2VuZXJhdG9yYgZwcm90bzM="));
+      descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
+          new pbr::FileDescriptor[] { global::Google.Protobuf.TestProtos.OldGenerator.OldExtensions2Reflection.Descriptor, },
+          new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.TestProtos.OldGenerator.TestMessage), global::Google.Protobuf.TestProtos.OldGenerator.TestMessage.Parser, null, null, null, null)
+          }));
+    }
+    #endregion
+
+  }
+  #region Messages
+  /// <summary>
+  /// We don't use this message other than to get its descriptor.
+  /// </summary>
+  public sealed partial class TestMessage : pb::IMessage<TestMessage> {
+    private static readonly pb::MessageParser<TestMessage> _parser = new pb::MessageParser<TestMessage>(() => new TestMessage());
+    private pb::UnknownFieldSet _unknownFields;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    public static pb::MessageParser<TestMessage> Parser { get { return _parser; } }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    public static pbr::MessageDescriptor Descriptor {
+      get { return global::Google.Protobuf.TestProtos.OldGenerator.OldExtensions1Reflection.Descriptor.MessageTypes[0]; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    pbr::MessageDescriptor pb::IMessage.Descriptor {
+      get { return Descriptor; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    public TestMessage() {
+      OnConstruction();
+    }
+
+    partial void OnConstruction();
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    public TestMessage(TestMessage other) : this() {
+      _unknownFields = pb::UnknownFieldSet.Clone(other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    public TestMessage Clone() {
+      return new TestMessage(this);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    public override bool Equals(object other) {
+      return Equals(other as TestMessage);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    public bool Equals(TestMessage other) {
+      if (ReferenceEquals(other, null)) {
+        return false;
+      }
+      if (ReferenceEquals(other, this)) {
+        return true;
+      }
+      return Equals(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    public override int GetHashCode() {
+      int hash = 1;
+      if (_unknownFields != null) {
+        hash ^= _unknownFields.GetHashCode();
+      }
+      return hash;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    public override string ToString() {
+      return pb::JsonFormatter.ToDiagnosticString(this);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    public void WriteTo(pb::CodedOutputStream output) {
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(output);
+      }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    public int CalculateSize() {
+      int size = 0;
+      if (_unknownFields != null) {
+        size += _unknownFields.CalculateSize();
+      }
+      return size;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    public void MergeFrom(TestMessage other) {
+      if (other == null) {
+        return;
+      }
+      _unknownFields = pb::UnknownFieldSet.MergeFrom(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    public void MergeFrom(pb::CodedInputStream input) {
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
+            break;
+        }
+      }
+    }
+
+  }
+
+  #endregion
+
+}
+
+#endregion Designer generated code

libs/protobuf/csharp/src/Google.Protobuf.Test.TestProtos/OldExtensions2.cs

@@ -0,0 +1,40 @@
+// <auto-generated>
+//     Generated by the protocol buffer compiler.  DO NOT EDIT!
+//     source: old_extensions2.proto
+// </auto-generated>
+#pragma warning disable 1591, 0612, 3021
+#region Designer generated code
+
+using pb = global::Google.Protobuf;
+using pbc = global::Google.Protobuf.Collections;
+using pbr = global::Google.Protobuf.Reflection;
+using scg = global::System.Collections.Generic;
+namespace Google.Protobuf.TestProtos.OldGenerator {
+
+  /// <summary>Holder for reflection information generated from old_extensions2.proto</summary>
+  public static partial class OldExtensions2Reflection {
+
+    #region Descriptor
+    /// <summary>File descriptor for old_extensions2.proto</summary>
+    public static pbr::FileDescriptor Descriptor {
+      get { return descriptor; }
+    }
+    private static pbr::FileDescriptor descriptor;
+
+    static OldExtensions2Reflection() {
+      byte[] descriptorData = global::System.Convert.FromBase64String(
+          string.Concat(
+            "ChVvbGRfZXh0ZW5zaW9uczIucHJvdG8aIGdvb2dsZS9wcm90b2J1Zi9kZXNj",
+            "cmlwdG9yLnByb3RvOjQKCm1ldGhvZF9leHQSHi5nb29nbGUucHJvdG9idWYu",
+            "TWV0aG9kT3B0aW9ucxiHrUsgASgJQiqqAidHb29nbGUuUHJvdG9idWYuVGVz",
+            "dFByb3Rvcy5PbGRHZW5lcmF0b3JiBnByb3RvMw=="));
+      descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
+          new pbr::FileDescriptor[] { pbr::FileDescriptor.DescriptorProtoFileDescriptor, },
+          new pbr::GeneratedClrTypeInfo(null, null));
+    }
+    #endregion
+
+  }
+}
+
+#endregion Designer generated code

libs/protobuf/csharp/src/Google.Protobuf.Test.TestProtos/UnittestImport.cs

@@ -0,0 +1,272 @@
+// <auto-generated>
+//     Generated by the protocol buffer compiler.  DO NOT EDIT!
+//     source: unittest_import.proto
+// </auto-generated>
+#pragma warning disable 1591, 0612, 3021, 8981
+#region Designer generated code
+
+using pb = global::Google.Protobuf;
+using pbc = global::Google.Protobuf.Collections;
+using pbr = global::Google.Protobuf.Reflection;
+using scg = global::System.Collections.Generic;
+namespace Google.Protobuf.TestProtos.Proto2 {
+
+  /// <summary>Holder for reflection information generated from unittest_import.proto</summary>
+  public static partial class UnittestImportReflection {
+
+    #region Descriptor
+    /// <summary>File descriptor for unittest_import.proto</summary>
+    public static pbr::FileDescriptor Descriptor {
+      get { return descriptor; }
+    }
+    private static pbr::FileDescriptor descriptor;
+
+    static UnittestImportReflection() {
+      byte[] descriptorData = global::System.Convert.FromBase64String(
+          string.Concat(
+            "ChV1bml0dGVzdF9pbXBvcnQucHJvdG8SH3Byb3RvYnVmX3VuaXR0ZXN0X2lt",
+            "cG9ydF9wcm90bzIaHHVuaXR0ZXN0X2ltcG9ydF9wdWJsaWMucHJvdG8iGgoN",
+            "SW1wb3J0TWVzc2FnZRIJCgFkGAEgASgFKjwKCkltcG9ydEVudW0SDgoKSU1Q",
+            "T1JUX0ZPTxAHEg4KCklNUE9SVF9CQVIQCBIOCgpJTVBPUlRfQkFaEAkqMQoQ",
+            "SW1wb3J0RW51bUZvck1hcBILCgdVTktOT1dOEAASBwoDRk9PEAESBwoDQkFS",
+            "EAJCKUgB+AEBqgIhR29vZ2xlLlByb3RvYnVmLlRlc3RQcm90b3MuUHJvdG8y",
+            "UAA="));
+      descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
+          new pbr::FileDescriptor[] { global::Google.Protobuf.TestProtos.Proto2.UnittestImportPublicReflection.Descriptor, },
+          new pbr::GeneratedClrTypeInfo(new[] {typeof(global::Google.Protobuf.TestProtos.Proto2.ImportEnum), typeof(global::Google.Protobuf.TestProtos.Proto2.ImportEnumForMap), }, null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.TestProtos.Proto2.ImportMessage), global::Google.Protobuf.TestProtos.Proto2.ImportMessage.Parser, new[]{ "D" }, null, null, null, null)
+          }));
+    }
+    #endregion
+
+  }
+  #region Enums
+  public enum ImportEnum {
+    [pbr::OriginalName("IMPORT_FOO")] ImportFoo = 7,
+    [pbr::OriginalName("IMPORT_BAR")] ImportBar = 8,
+    [pbr::OriginalName("IMPORT_BAZ")] ImportBaz = 9,
+  }
+
+  /// <summary>
+  /// To use an enum in a map, it must has the first value as 0.
+  /// </summary>
+  public enum ImportEnumForMap {
+    [pbr::OriginalName("UNKNOWN")] Unknown = 0,
+    [pbr::OriginalName("FOO")] Foo = 1,
+    [pbr::OriginalName("BAR")] Bar = 2,
+  }
+
+  #endregion
+
+  #region Messages
+  public sealed partial class ImportMessage : pb::IMessage<ImportMessage>
+  #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      , pb::IBufferMessage
+  #endif
+  {
+    private static readonly pb::MessageParser<ImportMessage> _parser = new pb::MessageParser<ImportMessage>(() => new ImportMessage());
+    private pb::UnknownFieldSet _unknownFields;
+    private int _hasBits0;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pb::MessageParser<ImportMessage> Parser { get { return _parser; } }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pbr::MessageDescriptor Descriptor {
+      get { return global::Google.Protobuf.TestProtos.Proto2.UnittestImportReflection.Descriptor.MessageTypes[0]; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    pbr::MessageDescriptor pb::IMessage.Descriptor {
+      get { return Descriptor; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public ImportMessage() {
+      OnConstruction();
+    }
+
+    partial void OnConstruction();
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public ImportMessage(ImportMessage other) : this() {
+      _hasBits0 = other._hasBits0;
+      d_ = other.d_;
+      _unknownFields = pb::UnknownFieldSet.Clone(other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public ImportMessage Clone() {
+      return new ImportMessage(this);
+    }
+
+    /// <summary>Field number for the "d" field.</summary>
+    public const int DFieldNumber = 1;
+    private readonly static int DDefaultValue = 0;
+
+    private int d_;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int D {
+      get { if ((_hasBits0 & 1) != 0) { return d_; } else { return DDefaultValue; } }
+      set {
+        _hasBits0 |= 1;
+        d_ = value;
+      }
+    }
+    /// <summary>Gets whether the "d" field is set</summary>
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public bool HasD {
+      get { return (_hasBits0 & 1) != 0; }
+    }
+    /// <summary>Clears the value of the "d" field</summary>
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void ClearD() {
+      _hasBits0 &= ~1;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override bool Equals(object other) {
+      return Equals(other as ImportMessage);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public bool Equals(ImportMessage other) {
+      if (ReferenceEquals(other, null)) {
+        return false;
+      }
+      if (ReferenceEquals(other, this)) {
+        return true;
+      }
+      if (D != other.D) return false;
+      return Equals(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override int GetHashCode() {
+      int hash = 1;
+      if (HasD) hash ^= D.GetHashCode();
+      if (_unknownFields != null) {
+        hash ^= _unknownFields.GetHashCode();
+      }
+      return hash;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override string ToString() {
+      return pb::JsonFormatter.ToDiagnosticString(this);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void WriteTo(pb::CodedOutputStream output) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      output.WriteRawMessage(this);
+    #else
+      if (HasD) {
+        output.WriteRawTag(8);
+        output.WriteInt32(D);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(output);
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalWriteTo(ref pb::WriteContext output) {
+      if (HasD) {
+        output.WriteRawTag(8);
+        output.WriteInt32(D);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(ref output);
+      }
+    }
+    #endif
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int CalculateSize() {
+      int size = 0;
+      if (HasD) {
+        size += 1 + pb::CodedOutputStream.ComputeInt32Size(D);
+      }
+      if (_unknownFields != null) {
+        size += _unknownFields.CalculateSize();
+      }
+      return size;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(ImportMessage other) {
+      if (other == null) {
+        return;
+      }
+      if (other.HasD) {
+        D = other.D;
+      }
+      _unknownFields = pb::UnknownFieldSet.MergeFrom(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(pb::CodedInputStream input) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      input.ReadRawMessage(this);
+    #else
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
+            break;
+          case 8: {
+            D = input.ReadInt32();
+            break;
+          }
+        }
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalMergeFrom(ref pb::ParseContext input) {
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, ref input);
+            break;
+          case 8: {
+            D = input.ReadInt32();
+            break;
+          }
+        }
+      }
+    }
+    #endif
+
+  }
+
+  #endregion
+
+}
+
+#endregion Designer generated code

libs/protobuf/csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportProto3.cs

@@ -0,0 +1,246 @@
+// <auto-generated>
+//     Generated by the protocol buffer compiler.  DO NOT EDIT!
+//     source: unittest_import_proto3.proto
+// </auto-generated>
+#pragma warning disable 1591, 0612, 3021, 8981
+#region Designer generated code
+
+using pb = global::Google.Protobuf;
+using pbc = global::Google.Protobuf.Collections;
+using pbr = global::Google.Protobuf.Reflection;
+using scg = global::System.Collections.Generic;
+namespace Google.Protobuf.TestProtos {
+
+  /// <summary>Holder for reflection information generated from unittest_import_proto3.proto</summary>
+  public static partial class UnittestImportProto3Reflection {
+
+    #region Descriptor
+    /// <summary>File descriptor for unittest_import_proto3.proto</summary>
+    public static pbr::FileDescriptor Descriptor {
+      get { return descriptor; }
+    }
+    private static pbr::FileDescriptor descriptor;
+
+    static UnittestImportProto3Reflection() {
+      byte[] descriptorData = global::System.Convert.FromBase64String(
+          string.Concat(
+            "Chx1bml0dGVzdF9pbXBvcnRfcHJvdG8zLnByb3RvEhhwcm90b2J1Zl91bml0",
+            "dGVzdF9pbXBvcnQaI3VuaXR0ZXN0X2ltcG9ydF9wdWJsaWNfcHJvdG8zLnBy",
+            "b3RvIhoKDUltcG9ydE1lc3NhZ2USCQoBZBgBIAEoBSpZCgpJbXBvcnRFbnVt",
+            "EhsKF0lNUE9SVF9FTlVNX1VOU1BFQ0lGSUVEEAASDgoKSU1QT1JUX0ZPTxAH",
+            "Eg4KCklNUE9SVF9CQVIQCBIOCgpJTVBPUlRfQkFaEAlCHaoCGkdvb2dsZS5Q",
+            "cm90b2J1Zi5UZXN0UHJvdG9zUABiBnByb3RvMw=="));
+      descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
+          new pbr::FileDescriptor[] { global::Google.Protobuf.TestProtos.UnittestImportPublicProto3Reflection.Descriptor, },
+          new pbr::GeneratedClrTypeInfo(new[] {typeof(global::Google.Protobuf.TestProtos.ImportEnum), }, null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.TestProtos.ImportMessage), global::Google.Protobuf.TestProtos.ImportMessage.Parser, new[]{ "D" }, null, null, null, null)
+          }));
+    }
+    #endregion
+
+  }
+  #region Enums
+  public enum ImportEnum {
+    [pbr::OriginalName("IMPORT_ENUM_UNSPECIFIED")] Unspecified = 0,
+    [pbr::OriginalName("IMPORT_FOO")] ImportFoo = 7,
+    [pbr::OriginalName("IMPORT_BAR")] ImportBar = 8,
+    [pbr::OriginalName("IMPORT_BAZ")] ImportBaz = 9,
+  }
+
+  #endregion
+
+  #region Messages
+  public sealed partial class ImportMessage : pb::IMessage<ImportMessage>
+  #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      , pb::IBufferMessage
+  #endif
+  {
+    private static readonly pb::MessageParser<ImportMessage> _parser = new pb::MessageParser<ImportMessage>(() => new ImportMessage());
+    private pb::UnknownFieldSet _unknownFields;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pb::MessageParser<ImportMessage> Parser { get { return _parser; } }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pbr::MessageDescriptor Descriptor {
+      get { return global::Google.Protobuf.TestProtos.UnittestImportProto3Reflection.Descriptor.MessageTypes[0]; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    pbr::MessageDescriptor pb::IMessage.Descriptor {
+      get { return Descriptor; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public ImportMessage() {
+      OnConstruction();
+    }
+
+    partial void OnConstruction();
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public ImportMessage(ImportMessage other) : this() {
+      d_ = other.d_;
+      _unknownFields = pb::UnknownFieldSet.Clone(other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public ImportMessage Clone() {
+      return new ImportMessage(this);
+    }
+
+    /// <summary>Field number for the "d" field.</summary>
+    public const int DFieldNumber = 1;
+    private int d_;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int D {
+      get { return d_; }
+      set {
+        d_ = value;
+      }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override bool Equals(object other) {
+      return Equals(other as ImportMessage);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public bool Equals(ImportMessage other) {
+      if (ReferenceEquals(other, null)) {
+        return false;
+      }
+      if (ReferenceEquals(other, this)) {
+        return true;
+      }
+      if (D != other.D) return false;
+      return Equals(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override int GetHashCode() {
+      int hash = 1;
+      if (D != 0) hash ^= D.GetHashCode();
+      if (_unknownFields != null) {
+        hash ^= _unknownFields.GetHashCode();
+      }
+      return hash;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override string ToString() {
+      return pb::JsonFormatter.ToDiagnosticString(this);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void WriteTo(pb::CodedOutputStream output) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      output.WriteRawMessage(this);
+    #else
+      if (D != 0) {
+        output.WriteRawTag(8);
+        output.WriteInt32(D);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(output);
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalWriteTo(ref pb::WriteContext output) {
+      if (D != 0) {
+        output.WriteRawTag(8);
+        output.WriteInt32(D);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(ref output);
+      }
+    }
+    #endif
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int CalculateSize() {
+      int size = 0;
+      if (D != 0) {
+        size += 1 + pb::CodedOutputStream.ComputeInt32Size(D);
+      }
+      if (_unknownFields != null) {
+        size += _unknownFields.CalculateSize();
+      }
+      return size;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(ImportMessage other) {
+      if (other == null) {
+        return;
+      }
+      if (other.D != 0) {
+        D = other.D;
+      }
+      _unknownFields = pb::UnknownFieldSet.MergeFrom(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(pb::CodedInputStream input) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      input.ReadRawMessage(this);
+    #else
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
+            break;
+          case 8: {
+            D = input.ReadInt32();
+            break;
+          }
+        }
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalMergeFrom(ref pb::ParseContext input) {
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, ref input);
+            break;
+          case 8: {
+            D = input.ReadInt32();
+            break;
+          }
+        }
+      }
+    }
+    #endif
+
+  }
+
+  #endregion
+
+}
+
+#endregion Designer generated code

libs/protobuf/csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportPublic.cs

@@ -0,0 +1,250 @@
+// <auto-generated>
+//     Generated by the protocol buffer compiler.  DO NOT EDIT!
+//     source: unittest_import_public.proto
+// </auto-generated>
+#pragma warning disable 1591, 0612, 3021, 8981
+#region Designer generated code
+
+using pb = global::Google.Protobuf;
+using pbc = global::Google.Protobuf.Collections;
+using pbr = global::Google.Protobuf.Reflection;
+using scg = global::System.Collections.Generic;
+namespace Google.Protobuf.TestProtos.Proto2 {
+
+  /// <summary>Holder for reflection information generated from unittest_import_public.proto</summary>
+  public static partial class UnittestImportPublicReflection {
+
+    #region Descriptor
+    /// <summary>File descriptor for unittest_import_public.proto</summary>
+    public static pbr::FileDescriptor Descriptor {
+      get { return descriptor; }
+    }
+    private static pbr::FileDescriptor descriptor;
+
+    static UnittestImportPublicReflection() {
+      byte[] descriptorData = global::System.Convert.FromBase64String(
+          string.Concat(
+            "Chx1bml0dGVzdF9pbXBvcnRfcHVibGljLnByb3RvEh9wcm90b2J1Zl91bml0",
+            "dGVzdF9pbXBvcnRfcHJvdG8yIiAKE1B1YmxpY0ltcG9ydE1lc3NhZ2USCQoB",
+            "ZRgBIAEoBUIkqgIhR29vZ2xlLlByb3RvYnVmLlRlc3RQcm90b3MuUHJvdG8y"));
+      descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
+          new pbr::FileDescriptor[] { },
+          new pbr::GeneratedClrTypeInfo(null, null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.TestProtos.Proto2.PublicImportMessage), global::Google.Protobuf.TestProtos.Proto2.PublicImportMessage.Parser, new[]{ "E" }, null, null, null, null)
+          }));
+    }
+    #endregion
+
+  }
+  #region Messages
+  public sealed partial class PublicImportMessage : pb::IMessage<PublicImportMessage>
+  #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      , pb::IBufferMessage
+  #endif
+  {
+    private static readonly pb::MessageParser<PublicImportMessage> _parser = new pb::MessageParser<PublicImportMessage>(() => new PublicImportMessage());
+    private pb::UnknownFieldSet _unknownFields;
+    private int _hasBits0;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pb::MessageParser<PublicImportMessage> Parser { get { return _parser; } }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pbr::MessageDescriptor Descriptor {
+      get { return global::Google.Protobuf.TestProtos.Proto2.UnittestImportPublicReflection.Descriptor.MessageTypes[0]; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    pbr::MessageDescriptor pb::IMessage.Descriptor {
+      get { return Descriptor; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public PublicImportMessage() {
+      OnConstruction();
+    }
+
+    partial void OnConstruction();
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public PublicImportMessage(PublicImportMessage other) : this() {
+      _hasBits0 = other._hasBits0;
+      e_ = other.e_;
+      _unknownFields = pb::UnknownFieldSet.Clone(other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public PublicImportMessage Clone() {
+      return new PublicImportMessage(this);
+    }
+
+    /// <summary>Field number for the "e" field.</summary>
+    public const int EFieldNumber = 1;
+    private readonly static int EDefaultValue = 0;
+
+    private int e_;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int E {
+      get { if ((_hasBits0 & 1) != 0) { return e_; } else { return EDefaultValue; } }
+      set {
+        _hasBits0 |= 1;
+        e_ = value;
+      }
+    }
+    /// <summary>Gets whether the "e" field is set</summary>
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public bool HasE {
+      get { return (_hasBits0 & 1) != 0; }
+    }
+    /// <summary>Clears the value of the "e" field</summary>
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void ClearE() {
+      _hasBits0 &= ~1;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override bool Equals(object other) {
+      return Equals(other as PublicImportMessage);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public bool Equals(PublicImportMessage other) {
+      if (ReferenceEquals(other, null)) {
+        return false;
+      }
+      if (ReferenceEquals(other, this)) {
+        return true;
+      }
+      if (E != other.E) return false;
+      return Equals(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override int GetHashCode() {
+      int hash = 1;
+      if (HasE) hash ^= E.GetHashCode();
+      if (_unknownFields != null) {
+        hash ^= _unknownFields.GetHashCode();
+      }
+      return hash;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override string ToString() {
+      return pb::JsonFormatter.ToDiagnosticString(this);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void WriteTo(pb::CodedOutputStream output) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      output.WriteRawMessage(this);
+    #else
+      if (HasE) {
+        output.WriteRawTag(8);
+        output.WriteInt32(E);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(output);
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalWriteTo(ref pb::WriteContext output) {
+      if (HasE) {
+        output.WriteRawTag(8);
+        output.WriteInt32(E);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(ref output);
+      }
+    }
+    #endif
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int CalculateSize() {
+      int size = 0;
+      if (HasE) {
+        size += 1 + pb::CodedOutputStream.ComputeInt32Size(E);
+      }
+      if (_unknownFields != null) {
+        size += _unknownFields.CalculateSize();
+      }
+      return size;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(PublicImportMessage other) {
+      if (other == null) {
+        return;
+      }
+      if (other.HasE) {
+        E = other.E;
+      }
+      _unknownFields = pb::UnknownFieldSet.MergeFrom(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(pb::CodedInputStream input) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      input.ReadRawMessage(this);
+    #else
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
+            break;
+          case 8: {
+            E = input.ReadInt32();
+            break;
+          }
+        }
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalMergeFrom(ref pb::ParseContext input) {
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, ref input);
+            break;
+          case 8: {
+            E = input.ReadInt32();
+            break;
+          }
+        }
+      }
+    }
+    #endif
+
+  }
+
+  #endregion
+
+}
+
+#endregion Designer generated code

libs/protobuf/csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportPublicProto3.cs

@@ -0,0 +1,234 @@
+// <auto-generated>
+//     Generated by the protocol buffer compiler.  DO NOT EDIT!
+//     source: unittest_import_public_proto3.proto
+// </auto-generated>
+#pragma warning disable 1591, 0612, 3021, 8981
+#region Designer generated code
+
+using pb = global::Google.Protobuf;
+using pbc = global::Google.Protobuf.Collections;
+using pbr = global::Google.Protobuf.Reflection;
+using scg = global::System.Collections.Generic;
+namespace Google.Protobuf.TestProtos {
+
+  /// <summary>Holder for reflection information generated from unittest_import_public_proto3.proto</summary>
+  public static partial class UnittestImportPublicProto3Reflection {
+
+    #region Descriptor
+    /// <summary>File descriptor for unittest_import_public_proto3.proto</summary>
+    public static pbr::FileDescriptor Descriptor {
+      get { return descriptor; }
+    }
+    private static pbr::FileDescriptor descriptor;
+
+    static UnittestImportPublicProto3Reflection() {
+      byte[] descriptorData = global::System.Convert.FromBase64String(
+          string.Concat(
+            "CiN1bml0dGVzdF9pbXBvcnRfcHVibGljX3Byb3RvMy5wcm90bxIYcHJvdG9i",
+            "dWZfdW5pdHRlc3RfaW1wb3J0IiAKE1B1YmxpY0ltcG9ydE1lc3NhZ2USCQoB",
+            "ZRgBIAEoBUIdqgIaR29vZ2xlLlByb3RvYnVmLlRlc3RQcm90b3NiBnByb3Rv",
+            "Mw=="));
+      descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
+          new pbr::FileDescriptor[] { },
+          new pbr::GeneratedClrTypeInfo(null, null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.TestProtos.PublicImportMessage), global::Google.Protobuf.TestProtos.PublicImportMessage.Parser, new[]{ "E" }, null, null, null, null)
+          }));
+    }
+    #endregion
+
+  }
+  #region Messages
+  public sealed partial class PublicImportMessage : pb::IMessage<PublicImportMessage>
+  #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      , pb::IBufferMessage
+  #endif
+  {
+    private static readonly pb::MessageParser<PublicImportMessage> _parser = new pb::MessageParser<PublicImportMessage>(() => new PublicImportMessage());
+    private pb::UnknownFieldSet _unknownFields;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pb::MessageParser<PublicImportMessage> Parser { get { return _parser; } }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pbr::MessageDescriptor Descriptor {
+      get { return global::Google.Protobuf.TestProtos.UnittestImportPublicProto3Reflection.Descriptor.MessageTypes[0]; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    pbr::MessageDescriptor pb::IMessage.Descriptor {
+      get { return Descriptor; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public PublicImportMessage() {
+      OnConstruction();
+    }
+
+    partial void OnConstruction();
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public PublicImportMessage(PublicImportMessage other) : this() {
+      e_ = other.e_;
+      _unknownFields = pb::UnknownFieldSet.Clone(other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public PublicImportMessage Clone() {
+      return new PublicImportMessage(this);
+    }
+
+    /// <summary>Field number for the "e" field.</summary>
+    public const int EFieldNumber = 1;
+    private int e_;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int E {
+      get { return e_; }
+      set {
+        e_ = value;
+      }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override bool Equals(object other) {
+      return Equals(other as PublicImportMessage);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public bool Equals(PublicImportMessage other) {
+      if (ReferenceEquals(other, null)) {
+        return false;
+      }
+      if (ReferenceEquals(other, this)) {
+        return true;
+      }
+      if (E != other.E) return false;
+      return Equals(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override int GetHashCode() {
+      int hash = 1;
+      if (E != 0) hash ^= E.GetHashCode();
+      if (_unknownFields != null) {
+        hash ^= _unknownFields.GetHashCode();
+      }
+      return hash;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override string ToString() {
+      return pb::JsonFormatter.ToDiagnosticString(this);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void WriteTo(pb::CodedOutputStream output) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      output.WriteRawMessage(this);
+    #else
+      if (E != 0) {
+        output.WriteRawTag(8);
+        output.WriteInt32(E);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(output);
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalWriteTo(ref pb::WriteContext output) {
+      if (E != 0) {
+        output.WriteRawTag(8);
+        output.WriteInt32(E);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(ref output);
+      }
+    }
+    #endif
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int CalculateSize() {
+      int size = 0;
+      if (E != 0) {
+        size += 1 + pb::CodedOutputStream.ComputeInt32Size(E);
+      }
+      if (_unknownFields != null) {
+        size += _unknownFields.CalculateSize();
+      }
+      return size;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(PublicImportMessage other) {
+      if (other == null) {
+        return;
+      }
+      if (other.E != 0) {
+        E = other.E;
+      }
+      _unknownFields = pb::UnknownFieldSet.MergeFrom(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(pb::CodedInputStream input) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      input.ReadRawMessage(this);
+    #else
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
+            break;
+          case 8: {
+            E = input.ReadInt32();
+            break;
+          }
+        }
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalMergeFrom(ref pb::ParseContext input) {
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, ref input);
+            break;
+          case 8: {
+            E = input.ReadInt32();
+            break;
+          }
+        }
+      }
+    }
+    #endif
+
+  }
+
+  #endregion
+
+}
+
+#endregion Designer generated code

libs/protobuf/csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936A.cs

@@ -0,0 +1,46 @@
+// <auto-generated>
+//     Generated by the protocol buffer compiler.  DO NOT EDIT!
+//     source: unittest_issue6936_a.proto
+// </auto-generated>
+#pragma warning disable 1591, 0612, 3021, 8981
+#region Designer generated code
+
+using pb = global::Google.Protobuf;
+using pbc = global::Google.Protobuf.Collections;
+using pbr = global::Google.Protobuf.Reflection;
+using scg = global::System.Collections.Generic;
+namespace UnitTest.Issues.TestProtos {
+
+  /// <summary>Holder for reflection information generated from unittest_issue6936_a.proto</summary>
+  public static partial class UnittestIssue6936AReflection {
+
+    #region Descriptor
+    /// <summary>File descriptor for unittest_issue6936_a.proto</summary>
+    public static pbr::FileDescriptor Descriptor {
+      get { return descriptor; }
+    }
+    private static pbr::FileDescriptor descriptor;
+
+    static UnittestIssue6936AReflection() {
+      byte[] descriptorData = global::System.Convert.FromBase64String(
+          string.Concat(
+            "Chp1bml0dGVzdF9pc3N1ZTY5MzZfYS5wcm90bxIPdW5pdHRlc3RfaXNzdWVz",
+            "GiBnb29nbGUvcHJvdG9idWYvZGVzY3JpcHRvci5wcm90bzouCgNvcHQSHy5n",
+            "b29nbGUucHJvdG9idWYuTWVzc2FnZU9wdGlvbnMY0IYDIAEoCUIdqgIaVW5p",
+            "dFRlc3QuSXNzdWVzLlRlc3RQcm90b3NiBnByb3RvMw=="));
+      descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
+          new pbr::FileDescriptor[] { global::Google.Protobuf.Reflection.DescriptorReflection.Descriptor, },
+          new pbr::GeneratedClrTypeInfo(null, new pb::Extension[] { UnittestIssue6936AExtensions.Opt }, null));
+    }
+    #endregion
+
+  }
+  /// <summary>Holder for extension identifiers generated from the top level of unittest_issue6936_a.proto</summary>
+  public static partial class UnittestIssue6936AExtensions {
+    public static readonly pb::Extension<global::Google.Protobuf.Reflection.MessageOptions, string> Opt =
+      new pb::Extension<global::Google.Protobuf.Reflection.MessageOptions, string>(50000, pb::FieldCodec.ForString(400002, ""));
+  }
+
+}
+
+#endregion Designer generated code

libs/protobuf/csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936B.cs

@@ -0,0 +1,196 @@
+// <auto-generated>
+//     Generated by the protocol buffer compiler.  DO NOT EDIT!
+//     source: unittest_issue6936_b.proto
+// </auto-generated>
+#pragma warning disable 1591, 0612, 3021, 8981
+#region Designer generated code
+
+using pb = global::Google.Protobuf;
+using pbc = global::Google.Protobuf.Collections;
+using pbr = global::Google.Protobuf.Reflection;
+using scg = global::System.Collections.Generic;
+namespace UnitTest.Issues.TestProtos {
+
+  /// <summary>Holder for reflection information generated from unittest_issue6936_b.proto</summary>
+  public static partial class UnittestIssue6936BReflection {
+
+    #region Descriptor
+    /// <summary>File descriptor for unittest_issue6936_b.proto</summary>
+    public static pbr::FileDescriptor Descriptor {
+      get { return descriptor; }
+    }
+    private static pbr::FileDescriptor descriptor;
+
+    static UnittestIssue6936BReflection() {
+      byte[] descriptorData = global::System.Convert.FromBase64String(
+          string.Concat(
+            "Chp1bml0dGVzdF9pc3N1ZTY5MzZfYi5wcm90bxIPdW5pdHRlc3RfaXNzdWVz",
+            "Ghp1bml0dGVzdF9pc3N1ZTY5MzZfYS5wcm90byIOCgNGb286B4K1GANmb29C",
+            "HaoCGlVuaXRUZXN0Lklzc3Vlcy5UZXN0UHJvdG9zYgZwcm90bzM="));
+      descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
+          new pbr::FileDescriptor[] { global::UnitTest.Issues.TestProtos.UnittestIssue6936AReflection.Descriptor, },
+          new pbr::GeneratedClrTypeInfo(null, null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::UnitTest.Issues.TestProtos.Foo), global::UnitTest.Issues.TestProtos.Foo.Parser, null, null, null, null, null)
+          }));
+    }
+    #endregion
+
+  }
+  #region Messages
+  public sealed partial class Foo : pb::IMessage<Foo>
+  #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      , pb::IBufferMessage
+  #endif
+  {
+    private static readonly pb::MessageParser<Foo> _parser = new pb::MessageParser<Foo>(() => new Foo());
+    private pb::UnknownFieldSet _unknownFields;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pb::MessageParser<Foo> Parser { get { return _parser; } }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pbr::MessageDescriptor Descriptor {
+      get { return global::UnitTest.Issues.TestProtos.UnittestIssue6936BReflection.Descriptor.MessageTypes[0]; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    pbr::MessageDescriptor pb::IMessage.Descriptor {
+      get { return Descriptor; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public Foo() {
+      OnConstruction();
+    }
+
+    partial void OnConstruction();
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public Foo(Foo other) : this() {
+      _unknownFields = pb::UnknownFieldSet.Clone(other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public Foo Clone() {
+      return new Foo(this);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override bool Equals(object other) {
+      return Equals(other as Foo);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public bool Equals(Foo other) {
+      if (ReferenceEquals(other, null)) {
+        return false;
+      }
+      if (ReferenceEquals(other, this)) {
+        return true;
+      }
+      return Equals(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override int GetHashCode() {
+      int hash = 1;
+      if (_unknownFields != null) {
+        hash ^= _unknownFields.GetHashCode();
+      }
+      return hash;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override string ToString() {
+      return pb::JsonFormatter.ToDiagnosticString(this);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void WriteTo(pb::CodedOutputStream output) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      output.WriteRawMessage(this);
+    #else
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(output);
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalWriteTo(ref pb::WriteContext output) {
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(ref output);
+      }
+    }
+    #endif
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int CalculateSize() {
+      int size = 0;
+      if (_unknownFields != null) {
+        size += _unknownFields.CalculateSize();
+      }
+      return size;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(Foo other) {
+      if (other == null) {
+        return;
+      }
+      _unknownFields = pb::UnknownFieldSet.MergeFrom(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(pb::CodedInputStream input) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      input.ReadRawMessage(this);
+    #else
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
+            break;
+        }
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalMergeFrom(ref pb::ParseContext input) {
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, ref input);
+            break;
+        }
+      }
+    }
+    #endif
+
+  }
+
+  #endregion
+
+}
+
+#endregion Designer generated code

libs/protobuf/csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936C.cs

@@ -0,0 +1,244 @@
+// <auto-generated>
+//     Generated by the protocol buffer compiler.  DO NOT EDIT!
+//     source: unittest_issue6936_c.proto
+// </auto-generated>
+#pragma warning disable 1591, 0612, 3021, 8981
+#region Designer generated code
+
+using pb = global::Google.Protobuf;
+using pbc = global::Google.Protobuf.Collections;
+using pbr = global::Google.Protobuf.Reflection;
+using scg = global::System.Collections.Generic;
+namespace UnitTest.Issues.TestProtos {
+
+  /// <summary>Holder for reflection information generated from unittest_issue6936_c.proto</summary>
+  public static partial class UnittestIssue6936CReflection {
+
+    #region Descriptor
+    /// <summary>File descriptor for unittest_issue6936_c.proto</summary>
+    public static pbr::FileDescriptor Descriptor {
+      get { return descriptor; }
+    }
+    private static pbr::FileDescriptor descriptor;
+
+    static UnittestIssue6936CReflection() {
+      byte[] descriptorData = global::System.Convert.FromBase64String(
+          string.Concat(
+            "Chp1bml0dGVzdF9pc3N1ZTY5MzZfYy5wcm90bxIPdW5pdHRlc3RfaXNzdWVz",
+            "Ghp1bml0dGVzdF9pc3N1ZTY5MzZfYS5wcm90bxoadW5pdHRlc3RfaXNzdWU2",
+            "OTM2X2IucHJvdG8iMQoDQmFyEiEKA2ZvbxgBIAEoCzIULnVuaXR0ZXN0X2lz",
+            "c3Vlcy5Gb286B4K1GANiYXJCHaoCGlVuaXRUZXN0Lklzc3Vlcy5UZXN0UHJv",
+            "dG9zYgZwcm90bzM="));
+      descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
+          new pbr::FileDescriptor[] { global::UnitTest.Issues.TestProtos.UnittestIssue6936AReflection.Descriptor, global::UnitTest.Issues.TestProtos.UnittestIssue6936BReflection.Descriptor, },
+          new pbr::GeneratedClrTypeInfo(null, null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::UnitTest.Issues.TestProtos.Bar), global::UnitTest.Issues.TestProtos.Bar.Parser, new[]{ "Foo" }, null, null, null, null)
+          }));
+    }
+    #endregion
+
+  }
+  #region Messages
+  public sealed partial class Bar : pb::IMessage<Bar>
+  #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      , pb::IBufferMessage
+  #endif
+  {
+    private static readonly pb::MessageParser<Bar> _parser = new pb::MessageParser<Bar>(() => new Bar());
+    private pb::UnknownFieldSet _unknownFields;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pb::MessageParser<Bar> Parser { get { return _parser; } }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pbr::MessageDescriptor Descriptor {
+      get { return global::UnitTest.Issues.TestProtos.UnittestIssue6936CReflection.Descriptor.MessageTypes[0]; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    pbr::MessageDescriptor pb::IMessage.Descriptor {
+      get { return Descriptor; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public Bar() {
+      OnConstruction();
+    }
+
+    partial void OnConstruction();
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public Bar(Bar other) : this() {
+      foo_ = other.foo_ != null ? other.foo_.Clone() : null;
+      _unknownFields = pb::UnknownFieldSet.Clone(other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public Bar Clone() {
+      return new Bar(this);
+    }
+
+    /// <summary>Field number for the "foo" field.</summary>
+    public const int FooFieldNumber = 1;
+    private global::UnitTest.Issues.TestProtos.Foo foo_;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public global::UnitTest.Issues.TestProtos.Foo Foo {
+      get { return foo_; }
+      set {
+        foo_ = value;
+      }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override bool Equals(object other) {
+      return Equals(other as Bar);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public bool Equals(Bar other) {
+      if (ReferenceEquals(other, null)) {
+        return false;
+      }
+      if (ReferenceEquals(other, this)) {
+        return true;
+      }
+      if (!object.Equals(Foo, other.Foo)) return false;
+      return Equals(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override int GetHashCode() {
+      int hash = 1;
+      if (foo_ != null) hash ^= Foo.GetHashCode();
+      if (_unknownFields != null) {
+        hash ^= _unknownFields.GetHashCode();
+      }
+      return hash;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override string ToString() {
+      return pb::JsonFormatter.ToDiagnosticString(this);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void WriteTo(pb::CodedOutputStream output) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      output.WriteRawMessage(this);
+    #else
+      if (foo_ != null) {
+        output.WriteRawTag(10);
+        output.WriteMessage(Foo);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(output);
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalWriteTo(ref pb::WriteContext output) {
+      if (foo_ != null) {
+        output.WriteRawTag(10);
+        output.WriteMessage(Foo);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(ref output);
+      }
+    }
+    #endif
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int CalculateSize() {
+      int size = 0;
+      if (foo_ != null) {
+        size += 1 + pb::CodedOutputStream.ComputeMessageSize(Foo);
+      }
+      if (_unknownFields != null) {
+        size += _unknownFields.CalculateSize();
+      }
+      return size;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(Bar other) {
+      if (other == null) {
+        return;
+      }
+      if (other.foo_ != null) {
+        if (foo_ == null) {
+          Foo = new global::UnitTest.Issues.TestProtos.Foo();
+        }
+        Foo.MergeFrom(other.Foo);
+      }
+      _unknownFields = pb::UnknownFieldSet.MergeFrom(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(pb::CodedInputStream input) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      input.ReadRawMessage(this);
+    #else
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
+            break;
+          case 10: {
+            if (foo_ == null) {
+              Foo = new global::UnitTest.Issues.TestProtos.Foo();
+            }
+            input.ReadMessage(Foo);
+            break;
+          }
+        }
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalMergeFrom(ref pb::ParseContext input) {
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, ref input);
+            break;
+          case 10: {
+            if (foo_ == null) {
+              Foo = new global::UnitTest.Issues.TestProtos.Foo();
+            }
+            input.ReadMessage(Foo);
+            break;
+          }
+        }
+      }
+    }
+    #endif
+
+  }
+
+  #endregion
+
+}
+
+#endregion Designer generated code

libs/protobuf/csharp/src/Google.Protobuf.Test.TestProtos/UnittestSelfreferentialOptions.cs

@@ -0,0 +1,379 @@
+// <auto-generated>
+//     Generated by the protocol buffer compiler.  DO NOT EDIT!
+//     source: unittest_selfreferential_options.proto
+// </auto-generated>
+#pragma warning disable 1591, 0612, 3021, 8981
+#region Designer generated code
+
+using pb = global::Google.Protobuf;
+using pbc = global::Google.Protobuf.Collections;
+using pbr = global::Google.Protobuf.Reflection;
+using scg = global::System.Collections.Generic;
+namespace UnitTest.Issues.TestProtos.SelfreferentialOptions {
+
+  /// <summary>Holder for reflection information generated from unittest_selfreferential_options.proto</summary>
+  public static partial class UnittestSelfreferentialOptionsReflection {
+
+    #region Descriptor
+    /// <summary>File descriptor for unittest_selfreferential_options.proto</summary>
+    public static pbr::FileDescriptor Descriptor {
+      get { return descriptor; }
+    }
+    private static pbr::FileDescriptor descriptor;
+
+    static UnittestSelfreferentialOptionsReflection() {
+      byte[] descriptorData = global::System.Convert.FromBase64String(
+          string.Concat(
+            "CiZ1bml0dGVzdF9zZWxmcmVmZXJlbnRpYWxfb3B0aW9ucy5wcm90bxIpcHJv",
+            "dG9idWZfdW5pdHRlc3Rfc2VsZnJlZmVyZW50aWFsX29wdGlvbnMaIGdvb2ds",
+            "ZS9wcm90b2J1Zi9kZXNjcmlwdG9yLnByb3RvIkwKCkZvb09wdGlvbnMSHgoH",
+            "aW50X29wdBgBIAEoBUINyj4KCAHAPgLKPgIIAxITCgNmb28YAiABKAVCBso+",
+            "AxDSCSoJCOgHEICAgIACOjkKC2Jhcl9vcHRpb25zEh0uZ29vZ2xlLnByb3Rv",
+            "YnVmLkZpZWxkT3B0aW9ucxjoByABKAVCBMA+0gk6agoLZm9vX29wdGlvbnMS",
+            "HS5nb29nbGUucHJvdG9idWYuRmllbGRPcHRpb25zGOkHIAEoCzI1LnByb3Rv",
+            "YnVmX3VuaXR0ZXN0X3NlbGZyZWZlcmVudGlhbF9vcHRpb25zLkZvb09wdGlv",
+            "bnM6SwoLZm9vX2ludF9vcHQSNS5wcm90b2J1Zl91bml0dGVzdF9zZWxmcmVm",
+            "ZXJlbnRpYWxfb3B0aW9ucy5Gb29PcHRpb25zGOgHIAEoBTqCAQoLZm9vX2Zv",
+            "b19vcHQSNS5wcm90b2J1Zl91bml0dGVzdF9zZWxmcmVmZXJlbnRpYWxfb3B0",
+            "aW9ucy5Gb29PcHRpb25zGOkHIAEoCzI1LnByb3RvYnVmX3VuaXR0ZXN0X3Nl",
+            "bGZyZWZlcmVudGlhbF9vcHRpb25zLkZvb09wdGlvbnNCNKoCMVVuaXRUZXN0",
+            "Lklzc3Vlcy5UZXN0UHJvdG9zLlNlbGZyZWZlcmVudGlhbE9wdGlvbnM="));
+      descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
+          new pbr::FileDescriptor[] { global::Google.Protobuf.Reflection.DescriptorReflection.Descriptor, },
+          new pbr::GeneratedClrTypeInfo(null, new pb::Extension[] { UnittestSelfreferentialOptionsExtensions.BarOptions, UnittestSelfreferentialOptionsExtensions.FooOptions, UnittestSelfreferentialOptionsExtensions.FooIntOpt, UnittestSelfreferentialOptionsExtensions.FooFooOpt }, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions), global::UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions.Parser, new[]{ "IntOpt", "Foo" }, null, null, null, null)
+          }));
+    }
+    #endregion
+
+  }
+  /// <summary>Holder for extension identifiers generated from the top level of unittest_selfreferential_options.proto</summary>
+  public static partial class UnittestSelfreferentialOptionsExtensions {
+    /// <summary>
+    /// Custom field option used on the definition of that field option.
+    /// </summary>
+    public static readonly pb::Extension<global::Google.Protobuf.Reflection.FieldOptions, int> BarOptions =
+      new pb::Extension<global::Google.Protobuf.Reflection.FieldOptions, int>(1000, pb::FieldCodec.ForInt32(8000, 0));
+    public static readonly pb::Extension<global::Google.Protobuf.Reflection.FieldOptions, global::UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions> FooOptions =
+      new pb::Extension<global::Google.Protobuf.Reflection.FieldOptions, global::UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions>(1001, pb::FieldCodec.ForMessage(8010, global::UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions.Parser));
+    public static readonly pb::Extension<global::UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions, int> FooIntOpt =
+      new pb::Extension<global::UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions, int>(1000, pb::FieldCodec.ForInt32(8000, 0));
+    public static readonly pb::Extension<global::UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions, global::UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions> FooFooOpt =
+      new pb::Extension<global::UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions, global::UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions>(1001, pb::FieldCodec.ForMessage(8010, global::UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions.Parser));
+  }
+
+  #region Messages
+  public sealed partial class FooOptions : pb::IExtendableMessage<FooOptions>
+  #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      , pb::IBufferMessage
+  #endif
+  {
+    private static readonly pb::MessageParser<FooOptions> _parser = new pb::MessageParser<FooOptions>(() => new FooOptions());
+    private pb::UnknownFieldSet _unknownFields;
+    private pb::ExtensionSet<FooOptions> _extensions;
+    private pb::ExtensionSet<FooOptions> _Extensions { get { return _extensions; } }
+    private int _hasBits0;
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pb::MessageParser<FooOptions> Parser { get { return _parser; } }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public static pbr::MessageDescriptor Descriptor {
+      get { return global::UnitTest.Issues.TestProtos.SelfreferentialOptions.UnittestSelfreferentialOptionsReflection.Descriptor.MessageTypes[0]; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    pbr::MessageDescriptor pb::IMessage.Descriptor {
+      get { return Descriptor; }
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public FooOptions() {
+      OnConstruction();
+    }
+
+    partial void OnConstruction();
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public FooOptions(FooOptions other) : this() {
+      _hasBits0 = other._hasBits0;
+      intOpt_ = other.intOpt_;
+      foo_ = other.foo_;
+      _unknownFields = pb::UnknownFieldSet.Clone(other._unknownFields);
+      _extensions = pb::ExtensionSet.Clone(other._extensions);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public FooOptions Clone() {
+      return new FooOptions(this);
+    }
+
+    /// <summary>Field number for the "int_opt" field.</summary>
+    public const int IntOptFieldNumber = 1;
+    private readonly static int IntOptDefaultValue = 0;
+
+    private int intOpt_;
+    /// <summary>
+    /// Custom field option used in definition of the extension message.
+    /// </summary>
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int IntOpt {
+      get { if ((_hasBits0 & 1) != 0) { return intOpt_; } else { return IntOptDefaultValue; } }
+      set {
+        _hasBits0 |= 1;
+        intOpt_ = value;
+      }
+    }
+    /// <summary>Gets whether the "int_opt" field is set</summary>
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public bool HasIntOpt {
+      get { return (_hasBits0 & 1) != 0; }
+    }
+    /// <summary>Clears the value of the "int_opt" field</summary>
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void ClearIntOpt() {
+      _hasBits0 &= ~1;
+    }
+
+    /// <summary>Field number for the "foo" field.</summary>
+    public const int FooFieldNumber = 2;
+    private readonly static int FooDefaultValue = 0;
+
+    private int foo_;
+    /// <summary>
+    /// Custom field option used in definition of the custom option's message.
+    /// </summary>
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int Foo {
+      get { if ((_hasBits0 & 2) != 0) { return foo_; } else { return FooDefaultValue; } }
+      set {
+        _hasBits0 |= 2;
+        foo_ = value;
+      }
+    }
+    /// <summary>Gets whether the "foo" field is set</summary>
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public bool HasFoo {
+      get { return (_hasBits0 & 2) != 0; }
+    }
+    /// <summary>Clears the value of the "foo" field</summary>
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void ClearFoo() {
+      _hasBits0 &= ~2;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override bool Equals(object other) {
+      return Equals(other as FooOptions);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public bool Equals(FooOptions other) {
+      if (ReferenceEquals(other, null)) {
+        return false;
+      }
+      if (ReferenceEquals(other, this)) {
+        return true;
+      }
+      if (IntOpt != other.IntOpt) return false;
+      if (Foo != other.Foo) return false;
+      if (!Equals(_extensions, other._extensions)) {
+        return false;
+      }
+      return Equals(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override int GetHashCode() {
+      int hash = 1;
+      if (HasIntOpt) hash ^= IntOpt.GetHashCode();
+      if (HasFoo) hash ^= Foo.GetHashCode();
+      if (_extensions != null) {
+        hash ^= _extensions.GetHashCode();
+      }
+      if (_unknownFields != null) {
+        hash ^= _unknownFields.GetHashCode();
+      }
+      return hash;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public override string ToString() {
+      return pb::JsonFormatter.ToDiagnosticString(this);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void WriteTo(pb::CodedOutputStream output) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      output.WriteRawMessage(this);
+    #else
+      if (HasIntOpt) {
+        output.WriteRawTag(8);
+        output.WriteInt32(IntOpt);
+      }
+      if (HasFoo) {
+        output.WriteRawTag(16);
+        output.WriteInt32(Foo);
+      }
+      if (_extensions != null) {
+        _extensions.WriteTo(output);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(output);
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalWriteTo(ref pb::WriteContext output) {
+      if (HasIntOpt) {
+        output.WriteRawTag(8);
+        output.WriteInt32(IntOpt);
+      }
+      if (HasFoo) {
+        output.WriteRawTag(16);
+        output.WriteInt32(Foo);
+      }
+      if (_extensions != null) {
+        _extensions.WriteTo(ref output);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(ref output);
+      }
+    }
+    #endif
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public int CalculateSize() {
+      int size = 0;
+      if (HasIntOpt) {
+        size += 1 + pb::CodedOutputStream.ComputeInt32Size(IntOpt);
+      }
+      if (HasFoo) {
+        size += 1 + pb::CodedOutputStream.ComputeInt32Size(Foo);
+      }
+      if (_extensions != null) {
+        size += _extensions.CalculateSize();
+      }
+      if (_unknownFields != null) {
+        size += _unknownFields.CalculateSize();
+      }
+      return size;
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(FooOptions other) {
+      if (other == null) {
+        return;
+      }
+      if (other.HasIntOpt) {
+        IntOpt = other.IntOpt;
+      }
+      if (other.HasFoo) {
+        Foo = other.Foo;
+      }
+      pb::ExtensionSet.MergeFrom(ref _extensions, other._extensions);
+      _unknownFields = pb::UnknownFieldSet.MergeFrom(_unknownFields, other._unknownFields);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    public void MergeFrom(pb::CodedInputStream input) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      input.ReadRawMessage(this);
+    #else
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            if (!pb::ExtensionSet.TryMergeFieldFrom(ref _extensions, input)) {
+              _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
+            }
+            break;
+          case 8: {
+            IntOpt = input.ReadInt32();
+            break;
+          }
+          case 16: {
+            Foo = input.ReadInt32();
+            break;
+          }
+        }
+      }
+    #endif
+    }
+
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
+    void pb::IBufferMessage.InternalMergeFrom(ref pb::ParseContext input) {
+      uint tag;
+      while ((tag = input.ReadTag()) != 0) {
+        switch(tag) {
+          default:
+            if (!pb::ExtensionSet.TryMergeFieldFrom(ref _extensions, ref input)) {
+              _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, ref input);
+            }
+            break;
+          case 8: {
+            IntOpt = input.ReadInt32();
+            break;
+          }
+          case 16: {
+            Foo = input.ReadInt32();
+            break;
+          }
+        }
+      }
+    }
+    #endif
+
+    public TValue GetExtension<TValue>(pb::Extension<FooOptions, TValue> extension) {
+      return pb::ExtensionSet.Get(ref _extensions, extension);
+    }
+    public pbc::RepeatedField<TValue> GetExtension<TValue>(pb::RepeatedExtension<FooOptions, TValue> extension) {
+      return pb::ExtensionSet.Get(ref _extensions, extension);
+    }
+    public pbc::RepeatedField<TValue> GetOrInitializeExtension<TValue>(pb::RepeatedExtension<FooOptions, TValue> extension) {
+      return pb::ExtensionSet.GetOrInitialize(ref _extensions, extension);
+    }
+    public void SetExtension<TValue>(pb::Extension<FooOptions, TValue> extension, TValue value) {
+      pb::ExtensionSet.Set(ref _extensions, extension, value);
+    }
+    public bool HasExtension<TValue>(pb::Extension<FooOptions, TValue> extension) {
+      return pb::ExtensionSet.Has(ref _extensions, extension);
+    }
+    public void ClearExtension<TValue>(pb::Extension<FooOptions, TValue> extension) {
+      pb::ExtensionSet.Clear(ref _extensions, extension);
+    }
+    public void ClearExtension<TValue>(pb::RepeatedExtension<FooOptions, TValue> extension) {
+      pb::ExtensionSet.Clear(ref _extensions, extension);
+    }
+
+  }
+
+  #endregion
+
+}
+
+#endregion Designer generated code

libs/protobuf/csharp/src/Google.Protobuf.Test/Buffers/ArrayBufferWriter.cs

@@ -0,0 +1,225 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.Buffers;
+using System.Diagnostics;
+
+namespace Google.Protobuf.Buffers
+{
+    /// <summary>
+    /// Represents a heap-based, array-backed output sink into which <typeparam name="T"/> data can be written.
+    /// 
+    /// ArrayBufferWriter is originally from corefx, and has been contributed to Protobuf
+    /// https://github.com/dotnet/runtime/blob/071da4c41aa808c949a773b92dca6f88de9d11f3/src/libraries/Common/src/System/Buffers/ArrayBufferWriter.cs
+    /// </summary>
+    internal sealed class TestArrayBufferWriter<T> : IBufferWriter<T>
+    {
+        private T[] _buffer;
+        private int _index;
+
+        private const int DefaultInitialBufferSize = 256;
+
+        /// <summary>
+        /// Creates an instance of an <see cref="TestArrayBufferWriter{T}"/>, in which data can be written to,
+        /// with the default initial capacity.
+        /// </summary>
+        public TestArrayBufferWriter()
+        {
+            _buffer = new T[0];
+            _index = 0;
+        }
+
+        /// <summary>
+        /// Useful for testing writing to buffer writer with a lot of small segments.
+        /// If set, it limits the max number of bytes by which the buffer grows by at once.
+        /// </summary>
+        public int? MaxGrowBy { get; set; }
+
+        /// <summary>
+        /// Creates an instance of an <see cref="TestArrayBufferWriter{T}"/>, in which data can be written to,
+        /// with an initial capacity specified.
+        /// </summary>
+        /// <param name="initialCapacity">The minimum capacity with which to initialize the underlying buffer.</param>
+        /// <exception cref="ArgumentException">
+        /// Thrown when <paramref name="initialCapacity"/> is not positive (i.e. less than or equal to 0).
+        /// </exception>
+        public TestArrayBufferWriter(int initialCapacity)
+        {
+            if (initialCapacity <= 0)
+                throw new ArgumentException(nameof(initialCapacity));
+
+            _buffer = new T[initialCapacity];
+            _index = 0;
+        }
+
+        /// <summary>
+        /// Returns the data written to the underlying buffer so far, as a <see cref="ReadOnlyMemory{T}"/>.
+        /// </summary>
+        public ReadOnlyMemory<T> WrittenMemory => _buffer.AsMemory(0, _index);
+
+        /// <summary>
+        /// Returns the data written to the underlying buffer so far, as a <see cref="ReadOnlySpan{T}"/>.
+        /// </summary>
+        public ReadOnlySpan<T> WrittenSpan => _buffer.AsSpan(0, _index);
+
+        /// <summary>
+        /// Returns the amount of data written to the underlying buffer so far.
+        /// </summary>
+        public int WrittenCount => _index;
+
+        /// <summary>
+        /// Returns the total amount of space within the underlying buffer.
+        /// </summary>
+        public int Capacity => _buffer.Length;
+
+        /// <summary>
+        /// Returns the amount of space available that can still be written into without forcing the underlying buffer to grow.
+        /// </summary>
+        public int FreeCapacity => _buffer.Length - _index;
+
+        /// <summary>
+        /// Clears the data written to the underlying buffer.
+        /// </summary>
+        /// <remarks>
+        /// You must clear the <see cref="TestArrayBufferWriter{T}"/> before trying to re-use it.
+        /// </remarks>
+        public void Clear()
+        {
+            Debug.Assert(_buffer.Length >= _index);
+            _buffer.AsSpan(0, _index).Clear();
+            _index = 0;
+        }
+
+        /// <summary>
+        /// Notifies <see cref="IBufferWriter{T}"/> that <paramref name="count"/> amount of data was written to the output <see cref="Span{T}"/>/<see cref="Memory{T}"/>
+        /// </summary>
+        /// <exception cref="ArgumentException">
+        /// Thrown when <paramref name="count"/> is negative.
+        /// </exception>
+        /// <exception cref="InvalidOperationException">
+        /// Thrown when attempting to advance past the end of the underlying buffer.
+        /// </exception>
+        /// <remarks>
+        /// You must request a new buffer after calling Advance to continue writing more data and cannot write to a previously acquired buffer.
+        /// </remarks>
+        public void Advance(int count)
+        {
+            if (count < 0)
+                throw new ArgumentException(nameof(count));
+
+            if (_index > _buffer.Length - count)
+                throw new InvalidOperationException("Advanced past capacity.");
+
+            _index += count;
+        }
+
+        /// <summary>
+        /// Returns a <see cref="Memory{T}"/> to write to that is at least the requested length (specified by <paramref name="sizeHint"/>).
+        /// If no <paramref name="sizeHint"/> is provided (or it's equal to <code>0</code>), some non-empty buffer is returned.
+        /// </summary>
+        /// <exception cref="ArgumentException">
+        /// Thrown when <paramref name="sizeHint"/> is negative.
+        /// </exception>
+        /// <remarks>
+        /// This will never return an empty <see cref="Memory{T}"/>.
+        /// </remarks>
+        /// <remarks>
+        /// There is no guarantee that successive calls will return the same buffer or the same-sized buffer.
+        /// </remarks>
+        /// <remarks>
+        /// You must request a new buffer after calling Advance to continue writing more data and cannot write to a previously acquired buffer.
+        /// </remarks>
+        public Memory<T> GetMemory(int sizeHint = 0)
+        {
+            CheckAndResizeBuffer(sizeHint);
+            Debug.Assert(_buffer.Length > _index);
+            return _buffer.AsMemory(_index);
+        }
+
+        /// <summary>
+        /// Returns a <see cref="Span{T}"/> to write to that is at least the requested length (specified by <paramref name="sizeHint"/>).
+        /// If no <paramref name="sizeHint"/> is provided (or it's equal to <code>0</code>), some non-empty buffer is returned.
+        /// </summary>
+        /// <exception cref="ArgumentException">
+        /// Thrown when <paramref name="sizeHint"/> is negative.
+        /// </exception>
+        /// <remarks>
+        /// This will never return an empty <see cref="Span{T}"/>.
+        /// </remarks>
+        /// <remarks>
+        /// There is no guarantee that successive calls will return the same buffer or the same-sized buffer.
+        /// </remarks>
+        /// <remarks>
+        /// You must request a new buffer after calling Advance to continue writing more data and cannot write to a previously acquired buffer.
+        /// </remarks>
+        public Span<T> GetSpan(int sizeHint = 0)
+        {
+            CheckAndResizeBuffer(sizeHint);
+            Debug.Assert(_buffer.Length > _index);
+            return _buffer.AsSpan(_index);
+        }
+
+        private void CheckAndResizeBuffer(int sizeHint)
+        {
+            if (sizeHint < 0)
+                throw new ArgumentException(nameof(sizeHint));
+
+            if (sizeHint == 0)
+            {
+                sizeHint = 1;
+            }
+
+            if (sizeHint > FreeCapacity)
+            {
+                int growBy = Math.Max(sizeHint, _buffer.Length);
+
+                if (_buffer.Length == 0)
+                {
+                    growBy = Math.Max(growBy, DefaultInitialBufferSize);
+                }
+
+                // enable tests that write to small buffer segments
+                if (MaxGrowBy.HasValue && growBy > MaxGrowBy.Value)
+                {
+                    growBy = MaxGrowBy.Value;
+                }
+
+                int newSize = checked(_buffer.Length + growBy);
+
+                Array.Resize(ref _buffer, newSize);
+            }
+
+            Debug.Assert(FreeCapacity > 0 && FreeCapacity >= sizeHint);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/ByteStringTest.cs

@@ -0,0 +1,429 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.Text;
+using NUnit.Framework;
+using System.IO;
+using System.Collections.Generic;
+using System.Collections;
+using System.Linq;
+using System.Buffers;
+using System.Runtime.InteropServices;
+using System.Threading;
+using System.Runtime.CompilerServices;
+using System.Threading.Tasks;
+
+namespace Google.Protobuf
+{
+    public class ByteStringTest
+    {
+        [Test]
+        public void Equality()
+        {
+            ByteString b1 = ByteString.CopyFrom(1, 2, 3);
+            ByteString b2 = ByteString.CopyFrom(1, 2, 3);
+            ByteString b3 = ByteString.CopyFrom(1, 2, 4);
+            ByteString b4 = ByteString.CopyFrom(1, 2, 3, 4);
+            EqualityTester.AssertEquality(b1, b1);
+            EqualityTester.AssertEquality(b1, b2);
+            EqualityTester.AssertInequality(b1, b3);
+            EqualityTester.AssertInequality(b1, b4);
+            EqualityTester.AssertInequality(b1, null);
+            EqualityTester.AssertEquality(ByteString.Empty, ByteString.Empty);
+#pragma warning disable 1718 // Deliberately calling ==(b1, b1) and !=(b1, b1)
+            Assert.IsTrue(b1 == b1);
+            Assert.IsTrue(b1 == b2);
+            Assert.IsFalse(b1 == b3);
+            Assert.IsFalse(b1 == b4);
+            Assert.IsFalse(b1 == null);
+            Assert.IsTrue((ByteString) null == null);
+            Assert.IsFalse(b1 != b1);
+            Assert.IsFalse(b1 != b2);
+            Assert.IsTrue(ByteString.Empty == ByteString.Empty);
+#pragma warning restore 1718
+            Assert.IsTrue(b1 != b3);
+            Assert.IsTrue(b1 != b4);
+            Assert.IsTrue(b1 != null);
+            Assert.IsFalse((ByteString) null != null);
+        }
+
+        [Test]
+        public void EmptyByteStringHasZeroSize()
+        {
+            Assert.AreEqual(0, ByteString.Empty.Length);
+        }
+
+        [Test]
+        public void CopyFromStringWithExplicitEncoding()
+        {
+            ByteString bs = ByteString.CopyFrom("AB", Encoding.Unicode);
+            Assert.AreEqual(4, bs.Length);
+            Assert.AreEqual(65, bs[0]);
+            Assert.AreEqual(0, bs[1]);
+            Assert.AreEqual(66, bs[2]);
+            Assert.AreEqual(0, bs[3]);
+        }
+
+        [Test]
+        public void IsEmptyWhenEmpty()
+        {
+            Assert.IsTrue(ByteString.CopyFromUtf8("").IsEmpty);
+        }
+
+        [Test]
+        public void IsEmptyWhenNotEmpty()
+        {
+            Assert.IsFalse(ByteString.CopyFromUtf8("X").IsEmpty);
+        }
+
+        [Test]
+        public void CopyFromByteArrayCopiesContents()
+        {
+            byte[] data = new byte[1];
+            data[0] = 10;
+            ByteString bs = ByteString.CopyFrom(data);
+            Assert.AreEqual(10, bs[0]);
+            data[0] = 5;
+            Assert.AreEqual(10, bs[0]);
+        }
+
+        [Test]
+        public void CopyFromReadOnlySpanCopiesContents()
+        {
+            byte[] data = new byte[1];
+            data[0] = 10;
+            ReadOnlySpan<byte> byteSpan = data;
+            var bs = ByteString.CopyFrom(byteSpan);
+            Assert.AreEqual(10, bs[0]);
+            data[0] = 5;
+            Assert.AreEqual(10, bs[0]);
+        }
+
+        [Test]
+        public void ToByteArrayCopiesContents()
+        {
+            ByteString bs = ByteString.CopyFromUtf8("Hello");
+            byte[] data = bs.ToByteArray();
+            Assert.AreEqual((byte)'H', data[0]);
+            Assert.AreEqual((byte)'H', bs[0]);
+            data[0] = 0;
+            Assert.AreEqual(0, data[0]);
+            Assert.AreEqual((byte)'H', bs[0]);
+        }
+
+        [Test]
+        public void CopyFromUtf8UsesUtf8()
+        {
+            ByteString bs = ByteString.CopyFromUtf8("\u20ac");
+            Assert.AreEqual(3, bs.Length);
+            Assert.AreEqual(0xe2, bs[0]);
+            Assert.AreEqual(0x82, bs[1]);
+            Assert.AreEqual(0xac, bs[2]);
+        }
+
+        [Test]
+        public void CopyFromPortion()
+        {
+            byte[] data = new byte[] {0, 1, 2, 3, 4, 5, 6};
+            ByteString bs = ByteString.CopyFrom(data, 2, 3);
+            Assert.AreEqual(3, bs.Length);
+            Assert.AreEqual(2, bs[0]);
+            Assert.AreEqual(3, bs[1]);
+        }
+
+        [Test]
+        public void CopyTo()
+        {
+            byte[] data = new byte[] { 0, 1, 2, 3, 4, 5, 6 };
+            ByteString bs = ByteString.CopyFrom(data);
+
+            byte[] dest = new byte[data.Length];
+            bs.CopyTo(dest, 0);
+
+            CollectionAssert.AreEqual(data, dest);
+        }
+
+        [Test]
+        public void GetEnumerator()
+        {
+            byte[] data = new byte[] { 0, 1, 2, 3, 4, 5, 6 };
+            ByteString bs = ByteString.CopyFrom(data);
+
+            IEnumerator<byte> genericEnumerator = bs.GetEnumerator();
+            Assert.IsTrue(genericEnumerator.MoveNext());
+            Assert.AreEqual(0, genericEnumerator.Current);
+
+            IEnumerator enumerator = ((IEnumerable)bs).GetEnumerator();
+            Assert.IsTrue(enumerator.MoveNext());
+            Assert.AreEqual(0, enumerator.Current);
+
+            // Call via LINQ
+            CollectionAssert.AreEqual(bs.Span.ToArray(), bs.ToArray());
+        }
+
+        [Test]
+        public void UnsafeWrap()
+        {
+            byte[] data = new byte[] { 0, 1, 2, 3, 4, 5, 6 };
+            ByteString bs = UnsafeByteOperations.UnsafeWrap(data.AsMemory(2, 3));
+            ReadOnlySpan<byte> s = bs.Span;
+
+            Assert.AreEqual(3, s.Length);
+            Assert.AreEqual(2, s[0]);
+            Assert.AreEqual(3, s[1]);
+            Assert.AreEqual(4, s[2]);
+
+            // Check that the value is not a copy
+            data[2] = byte.MaxValue;
+            Assert.AreEqual(byte.MaxValue, s[0]);
+        }
+
+        [Test]
+        public void CreateCodedInput_FromArraySegment()
+        {
+            byte[] data = new byte[] { 0, 1, 2, 3, 4, 5, 6 };
+            ByteString bs = UnsafeByteOperations.UnsafeWrap(data.AsMemory(2, 3));
+            CodedInputStream codedInputStream = bs.CreateCodedInput();
+
+            byte[] bytes = codedInputStream.ReadRawBytes(3);
+
+            Assert.AreEqual(3, bytes.Length);
+            Assert.AreEqual(2, bytes[0]);
+            Assert.AreEqual(3, bytes[1]);
+            Assert.AreEqual(4, bytes[2]);
+            Assert.IsTrue(codedInputStream.IsAtEnd);
+        }
+
+        [Test]
+        public void WriteToStream()
+        {
+            byte[] data = new byte[] { 0, 1, 2, 3, 4, 5, 6 };
+            ByteString bs = ByteString.CopyFrom(data);
+
+            MemoryStream ms = new MemoryStream();
+            bs.WriteTo(ms);
+
+            CollectionAssert.AreEqual(data, ms.ToArray());
+        }
+
+        [Test]
+        public void WriteToStream_Stackalloc()
+        {
+            byte[] data = Encoding.UTF8.GetBytes("Hello world");
+            Span<byte> s = stackalloc byte[data.Length];
+            data.CopyTo(s);
+
+            MemoryStream ms = new MemoryStream();
+
+            using (UnmanagedMemoryManager<byte> manager = new UnmanagedMemoryManager<byte>(s))
+            {
+                ByteString bs = ByteString.AttachBytes(manager.Memory);
+
+                bs.WriteTo(ms);
+            }
+
+            CollectionAssert.AreEqual(data, ms.ToArray());
+        }
+
+        [Test]
+        public void ToStringUtf8()
+        {
+            ByteString bs = ByteString.CopyFromUtf8("\u20ac");
+            Assert.AreEqual("\u20ac", bs.ToStringUtf8());
+        }
+
+        [Test]
+        public void ToStringWithExplicitEncoding()
+        {
+            ByteString bs = ByteString.CopyFrom("\u20ac", Encoding.Unicode);
+            Assert.AreEqual("\u20ac", bs.ToString(Encoding.Unicode));
+        }
+
+        [Test]
+        public void ToString_Stackalloc()
+        {
+            byte[] data = Encoding.UTF8.GetBytes("Hello world");
+            Span<byte> s = stackalloc byte[data.Length];
+            data.CopyTo(s);
+
+            using var manager = new UnmanagedMemoryManager<byte>(s);
+            ByteString bs = ByteString.AttachBytes(manager.Memory);
+            Assert.AreEqual("Hello world", bs.ToString(Encoding.UTF8));
+        }
+
+        [Test]
+        public void FromBase64_WithText()
+        {
+            byte[] data = new byte[] {0, 1, 2, 3, 4, 5, 6};
+            string base64 = Convert.ToBase64String(data);
+            ByteString bs = ByteString.FromBase64(base64);
+            Assert.AreEqual(data, bs.ToByteArray());
+        }
+
+        [Test]
+        public void FromBase64_Empty()
+        {
+            // Optimization which also fixes issue 61.
+            Assert.AreSame(ByteString.Empty, ByteString.FromBase64(""));
+        }
+
+        [Test]
+        public void ToBase64_Array()
+        {
+            ByteString bs = ByteString.CopyFrom(Encoding.UTF8.GetBytes("Hello world"));
+
+            Assert.AreEqual("SGVsbG8gd29ybGQ=", bs.ToBase64());
+        }
+
+        [Test]
+        public void ToBase64_Stackalloc()
+        {
+            byte[] data = Encoding.UTF8.GetBytes("Hello world");
+            Span<byte> s = stackalloc byte[data.Length];
+            data.CopyTo(s);
+
+            using var manager = new UnmanagedMemoryManager<byte>(s);
+            ByteString bs = ByteString.AttachBytes(manager.Memory);
+            Assert.AreEqual("SGVsbG8gd29ybGQ=", bs.ToBase64());
+        }
+
+        [Test]
+        public void FromStream_Seekable()
+        {
+            var stream = new MemoryStream(new byte[] { 1, 2, 3, 4, 5 });
+            // Consume the first byte, just to test that it's "from current position"
+            stream.ReadByte();
+            var actual = ByteString.FromStream(stream);
+            ByteString expected = ByteString.CopyFrom(2, 3, 4, 5);
+            Assert.AreEqual(expected, actual, $"{expected.ToBase64()} != {actual.ToBase64()}");
+        }
+
+        [Test]
+        public void FromStream_NotSeekable()
+        {
+            var stream = new MemoryStream(new byte[] { 1, 2, 3, 4, 5 });
+            // Consume the first byte, just to test that it's "from current position"
+            stream.ReadByte();
+            // Wrap the original stream in LimitedInputStream, which has CanSeek=false
+            var limitedStream = new LimitedInputStream(stream, 3);
+            var actual = ByteString.FromStream(limitedStream);
+            ByteString expected = ByteString.CopyFrom(2, 3, 4);
+            Assert.AreEqual(expected, actual, $"{expected.ToBase64()} != {actual.ToBase64()}");
+        }
+
+        [Test]
+        public async Task FromStreamAsync_Seekable()
+        {
+            var stream = new MemoryStream(new byte[] { 1, 2, 3, 4, 5 });
+            // Consume the first byte, just to test that it's "from current position"
+            stream.ReadByte();
+            var actual = await ByteString.FromStreamAsync(stream);
+            ByteString expected = ByteString.CopyFrom(2, 3, 4, 5);
+            Assert.AreEqual(expected, actual, $"{expected.ToBase64()} != {actual.ToBase64()}");
+        }
+
+        [Test]
+        public async Task FromStreamAsync_NotSeekable()
+        {
+            var stream = new MemoryStream(new byte[] { 1, 2, 3, 4, 5 });
+            // Consume the first byte, just to test that it's "from current position"
+            stream.ReadByte();
+            // Wrap the original stream in LimitedInputStream, which has CanSeek=false
+            var limitedStream = new LimitedInputStream(stream, 3);
+            var actual = await ByteString.FromStreamAsync(limitedStream);
+            ByteString expected = ByteString.CopyFrom(2, 3, 4);
+            Assert.AreEqual(expected, actual, $"{expected.ToBase64()} != {actual.ToBase64()}");
+        }
+
+        [Test]
+        public void GetHashCode_Regression()
+        {
+            // We used to have an awful hash algorithm where only the last four
+            // bytes were relevant. This is a regression test for
+            // https://github.com/protocolbuffers/protobuf/issues/2511
+
+            ByteString b1 = ByteString.CopyFrom(100, 1, 2, 3, 4);
+            ByteString b2 = ByteString.CopyFrom(200, 1, 2, 3, 4);
+            Assert.AreNotEqual(b1.GetHashCode(), b2.GetHashCode());
+        }
+
+        [Test]
+        public void GetContentsAsReadOnlySpan()
+        {
+            var byteString = ByteString.CopyFrom(1, 2, 3, 4, 5);
+            var copied = byteString.Span.ToArray();
+            CollectionAssert.AreEqual(byteString, copied);
+        }
+
+        [Test]
+        public void GetContentsAsReadOnlyMemory()
+        {
+            var byteString = ByteString.CopyFrom(1, 2, 3, 4, 5);
+            var copied = byteString.Memory.ToArray();
+            CollectionAssert.AreEqual(byteString, copied);
+        }
+
+        // Create Memory<byte> from non-array source.
+        // Use by ByteString tests that have optimized path for array backed Memory<byte>.
+        private sealed unsafe class UnmanagedMemoryManager<T> : MemoryManager<T> where T : unmanaged
+        {
+            private readonly T* _pointer;
+            private readonly int _length;
+
+            public UnmanagedMemoryManager(Span<T> span)
+            {
+                fixed (T* ptr = &MemoryMarshal.GetReference(span))
+                {
+                    _pointer = ptr;
+                    _length = span.Length;
+                }
+            }
+
+            public override Span<T> GetSpan() => new Span<T>(_pointer, _length);
+
+            public override MemoryHandle Pin(int elementIndex = 0)
+            {
+                if (elementIndex < 0 || elementIndex >= _length)
+                {
+                    throw new ArgumentOutOfRangeException(nameof(elementIndex));
+                }
+
+                return new MemoryHandle(_pointer + elementIndex);
+            }
+
+            public override void Unpin() { }
+
+            protected override void Dispose(bool disposing) { }
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/CodedInputStreamExtensions.cs

@@ -0,0 +1,53 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using NUnit.Framework;
+
+namespace Google.Protobuf
+{
+    internal static class CodedInputStreamExtensions
+    {
+        public static void AssertNextTag(this CodedInputStream input, uint expectedTag)
+        {
+            uint tag = input.ReadTag();
+            Assert.AreEqual(expectedTag, tag);
+        }
+
+        public static T ReadMessage<T>(this CodedInputStream stream, MessageParser<T> parser)
+            where T : IMessage<T>
+        {
+            var message = parser.CreateTemplate();
+            stream.ReadMessage(message);
+            return message;
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/CodedOutputStreamTest.cs

@@ -0,0 +1,579 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.IO;
+using Google.Protobuf.TestProtos;
+using Google.Protobuf.Buffers;
+using NUnit.Framework;
+using System.Text;
+
+namespace Google.Protobuf
+{
+    public class CodedOutputStreamTest
+    {
+        /// <summary>
+        /// Writes the given value using WriteRawVarint32() and WriteRawVarint64() and
+        /// checks that the result matches the given bytes
+        /// </summary>
+        private static void AssertWriteVarint(byte[] data, ulong value)
+        {
+            // Only do 32-bit write if the value fits in 32 bits.
+            if ((value >> 32) == 0)
+            {
+                // CodedOutputStream
+                MemoryStream rawOutput = new MemoryStream();
+                CodedOutputStream output = new CodedOutputStream(rawOutput);
+                output.WriteRawVarint32((uint) value);
+                output.Flush();
+                Assert.AreEqual(data, rawOutput.ToArray());
+
+                // IBufferWriter
+                var bufferWriter = new TestArrayBufferWriter<byte>();
+                WriteContext.Initialize(bufferWriter, out WriteContext ctx);
+                ctx.WriteUInt32((uint) value);
+                ctx.Flush();
+                Assert.AreEqual(data, bufferWriter.WrittenSpan.ToArray());
+
+                // Also try computing size.
+                Assert.AreEqual(data.Length, CodedOutputStream.ComputeRawVarint32Size((uint) value));
+            }
+
+            {
+                // CodedOutputStream
+                MemoryStream rawOutput = new MemoryStream();
+                CodedOutputStream output = new CodedOutputStream(rawOutput);
+                output.WriteRawVarint64(value);
+                output.Flush();
+                Assert.AreEqual(data, rawOutput.ToArray());
+
+                // IBufferWriter
+                var bufferWriter = new TestArrayBufferWriter<byte>();
+                WriteContext.Initialize(bufferWriter, out WriteContext ctx);
+                ctx.WriteUInt64(value);
+                ctx.Flush();
+                Assert.AreEqual(data, bufferWriter.WrittenSpan.ToArray());
+
+                // Also try computing size.
+                Assert.AreEqual(data.Length, CodedOutputStream.ComputeRawVarint64Size(value));
+            }
+
+            // Try different buffer sizes.
+            for (int bufferSize = 1; bufferSize <= 16; bufferSize *= 2)
+            {
+                // Only do 32-bit write if the value fits in 32 bits.
+                if ((value >> 32) == 0)
+                {
+                    MemoryStream rawOutput = new MemoryStream();
+                    CodedOutputStream output = new CodedOutputStream(rawOutput, bufferSize);
+                    output.WriteRawVarint32((uint) value);
+                    output.Flush();
+                    Assert.AreEqual(data, rawOutput.ToArray());
+
+                    var bufferWriter = new TestArrayBufferWriter<byte> { MaxGrowBy = bufferSize };
+                    WriteContext.Initialize(bufferWriter, out WriteContext ctx);
+                    ctx.WriteUInt32((uint) value);
+                    ctx.Flush();
+                    Assert.AreEqual(data, bufferWriter.WrittenSpan.ToArray());
+                }
+
+                {
+                    MemoryStream rawOutput = new MemoryStream();
+                    CodedOutputStream output = new CodedOutputStream(rawOutput, bufferSize);
+                    output.WriteRawVarint64(value);
+                    output.Flush();
+                    Assert.AreEqual(data, rawOutput.ToArray());
+
+                    var bufferWriter = new TestArrayBufferWriter<byte> { MaxGrowBy = bufferSize };
+                    WriteContext.Initialize(bufferWriter, out WriteContext ctx);
+                    ctx.WriteUInt64(value);
+                    ctx.Flush();
+                    Assert.AreEqual(data, bufferWriter.WrittenSpan.ToArray());
+                }
+
+            }
+        }
+
+        /// <summary>
+        /// Tests WriteRawVarint32() and WriteRawVarint64()
+        /// </summary>
+        [Test]
+        public void WriteVarint()
+        {
+            AssertWriteVarint(new byte[] {0x00}, 0);
+            AssertWriteVarint(new byte[] {0x01}, 1);
+            AssertWriteVarint(new byte[] {0x7f}, 127);
+            // 14882
+            AssertWriteVarint(new byte[] {0xa2, 0x74}, (0x22 << 0) | (0x74 << 7));
+            // 2961488830
+            AssertWriteVarint(new byte[] {0xbe, 0xf7, 0x92, 0x84, 0x0b},
+                              (0x3e << 0) | (0x77 << 7) | (0x12 << 14) | (0x04 << 21) |
+                              (0x0bL << 28));
+
+            // 64-bit
+            // 7256456126
+            AssertWriteVarint(new byte[] {0xbe, 0xf7, 0x92, 0x84, 0x1b},
+                              (0x3e << 0) | (0x77 << 7) | (0x12 << 14) | (0x04 << 21) |
+                              (0x1bL << 28));
+            // 41256202580718336
+            AssertWriteVarint(
+                new byte[] {0x80, 0xe6, 0xeb, 0x9c, 0xc3, 0xc9, 0xa4, 0x49},
+                (0x00 << 0) | (0x66 << 7) | (0x6b << 14) | (0x1c << 21) |
+                (0x43UL << 28) | (0x49L << 35) | (0x24UL << 42) | (0x49UL << 49));
+            // 11964378330978735131
+            AssertWriteVarint(
+                new byte[] {0x9b, 0xa8, 0xf9, 0xc2, 0xbb, 0xd6, 0x80, 0x85, 0xa6, 0x01},
+                unchecked((ulong)
+                          ((0x1b << 0) | (0x28 << 7) | (0x79 << 14) | (0x42 << 21) |
+                           (0x3bL << 28) | (0x56L << 35) | (0x00L << 42) |
+                           (0x05L << 49) | (0x26L << 56) | (0x01L << 63))));
+        }
+
+        /// <summary>
+        /// Parses the given bytes using WriteRawLittleEndian32() and checks
+        /// that the result matches the given value.
+        /// </summary>
+        private static void AssertWriteLittleEndian32(byte[] data, uint value)
+        {
+            {
+                var rawOutput = new MemoryStream();
+                var output = new CodedOutputStream(rawOutput);
+                output.WriteRawLittleEndian32(value);
+                output.Flush();
+                Assert.AreEqual(data, rawOutput.ToArray());
+
+                var bufferWriter = new TestArrayBufferWriter<byte>();
+                WriteContext.Initialize(bufferWriter, out WriteContext ctx);
+                ctx.WriteFixed32(value);
+                ctx.Flush();
+                Assert.AreEqual(data, bufferWriter.WrittenSpan.ToArray());
+            }
+
+            // Try different buffer sizes.
+            for (int bufferSize = 1; bufferSize <= 16; bufferSize *= 2)
+            {
+                var rawOutput = new MemoryStream();
+                var output = new CodedOutputStream(rawOutput, bufferSize);
+                output.WriteRawLittleEndian32(value);
+                output.Flush();
+                Assert.AreEqual(data, rawOutput.ToArray());
+
+                var bufferWriter = new TestArrayBufferWriter<byte> { MaxGrowBy = bufferSize };
+                WriteContext.Initialize(bufferWriter, out WriteContext ctx);
+                ctx.WriteFixed32(value);
+                ctx.Flush();
+                Assert.AreEqual(data, bufferWriter.WrittenSpan.ToArray());
+            }
+        }
+
+        /// <summary>
+        /// Parses the given bytes using WriteRawLittleEndian64() and checks
+        /// that the result matches the given value.
+        /// </summary>
+        private static void AssertWriteLittleEndian64(byte[] data, ulong value)
+        {
+            {
+                var rawOutput = new MemoryStream();
+                var output = new CodedOutputStream(rawOutput);
+                output.WriteRawLittleEndian64(value);
+                output.Flush();
+                Assert.AreEqual(data, rawOutput.ToArray());
+
+                var bufferWriter = new TestArrayBufferWriter<byte>();
+                WriteContext.Initialize(bufferWriter, out WriteContext ctx);
+                ctx.WriteFixed64(value);
+                ctx.Flush();
+                Assert.AreEqual(data, bufferWriter.WrittenSpan.ToArray());
+            }
+
+            // Try different block sizes.
+            for (int blockSize = 1; blockSize <= 16; blockSize *= 2)
+            {
+                var rawOutput = new MemoryStream();
+                var output = new CodedOutputStream(rawOutput, blockSize);
+                output.WriteRawLittleEndian64(value);
+                output.Flush();
+                Assert.AreEqual(data, rawOutput.ToArray());
+
+                var bufferWriter = new TestArrayBufferWriter<byte> { MaxGrowBy = blockSize };
+                WriteContext.Initialize(bufferWriter, out WriteContext ctx);
+                ctx.WriteFixed64(value);
+                ctx.Flush();
+                Assert.AreEqual(data, bufferWriter.WrittenSpan.ToArray());
+            }
+        }
+
+        /// <summary>
+        /// Tests writeRawLittleEndian32() and writeRawLittleEndian64().
+        /// </summary>
+        [Test]
+        public void WriteLittleEndian()
+        {
+            AssertWriteLittleEndian32(new byte[] {0x78, 0x56, 0x34, 0x12}, 0x12345678);
+            AssertWriteLittleEndian32(new byte[] {0xf0, 0xde, 0xbc, 0x9a}, 0x9abcdef0);
+
+            AssertWriteLittleEndian64(
+                new byte[] {0xf0, 0xde, 0xbc, 0x9a, 0x78, 0x56, 0x34, 0x12},
+                0x123456789abcdef0L);
+            AssertWriteLittleEndian64(
+                new byte[] {0x78, 0x56, 0x34, 0x12, 0xf0, 0xde, 0xbc, 0x9a},
+                0x9abcdef012345678UL);
+        }
+
+        [Test]
+        public void WriteWholeMessage_VaryingBlockSizes()
+        {
+            TestAllTypes message = SampleMessages.CreateFullTestAllTypes();
+
+            byte[] rawBytes = message.ToByteArray();
+
+            // Try different block sizes.
+            for (int blockSize = 1; blockSize < 256; blockSize *= 2)
+            {
+                MemoryStream rawOutput = new MemoryStream();
+                CodedOutputStream output = new CodedOutputStream(rawOutput, blockSize);
+                message.WriteTo(output);
+                output.Flush();
+                Assert.AreEqual(rawBytes, rawOutput.ToArray());
+
+                var bufferWriter = new TestArrayBufferWriter<byte> { MaxGrowBy = blockSize };
+                message.WriteTo(bufferWriter);
+                Assert.AreEqual(rawBytes, bufferWriter.WrittenSpan.ToArray()); 
+            }
+        }
+
+        [Test]
+        public void WriteContext_WritesWithFlushes()
+        {
+            TestAllTypes message = SampleMessages.CreateFullTestAllTypes();
+
+            MemoryStream expectedOutput = new MemoryStream();
+            CodedOutputStream output = new CodedOutputStream(expectedOutput);
+            output.WriteMessage(message);
+            output.Flush();
+            byte[] expectedBytes1 = expectedOutput.ToArray();
+
+            output.WriteMessage(message);
+            output.Flush();
+            byte[] expectedBytes2 = expectedOutput.ToArray();
+
+            var bufferWriter = new TestArrayBufferWriter<byte>();
+            WriteContext.Initialize(bufferWriter, out WriteContext ctx);
+            ctx.WriteMessage(message);
+            ctx.Flush();
+            Assert.AreEqual(expectedBytes1, bufferWriter.WrittenSpan.ToArray());
+
+            ctx.WriteMessage(message);
+            ctx.Flush();
+            Assert.AreEqual(expectedBytes2, bufferWriter.WrittenSpan.ToArray());
+        }
+        
+        [Test]
+        public void EncodeZigZag32()
+        {
+            Assert.AreEqual(0u, WritingPrimitives.EncodeZigZag32(0));
+            Assert.AreEqual(1u, WritingPrimitives.EncodeZigZag32(-1));
+            Assert.AreEqual(2u, WritingPrimitives.EncodeZigZag32(1));
+            Assert.AreEqual(3u, WritingPrimitives.EncodeZigZag32(-2));
+            Assert.AreEqual(0x7FFFFFFEu, WritingPrimitives.EncodeZigZag32(0x3FFFFFFF));
+            Assert.AreEqual(0x7FFFFFFFu, WritingPrimitives.EncodeZigZag32(unchecked((int) 0xC0000000)));
+            Assert.AreEqual(0xFFFFFFFEu, WritingPrimitives.EncodeZigZag32(0x7FFFFFFF));
+            Assert.AreEqual(0xFFFFFFFFu, WritingPrimitives.EncodeZigZag32(unchecked((int) 0x80000000)));
+        }
+
+        [Test]
+        public void EncodeZigZag64()
+        {
+            Assert.AreEqual(0u, WritingPrimitives.EncodeZigZag64(0));
+            Assert.AreEqual(1u, WritingPrimitives.EncodeZigZag64(-1));
+            Assert.AreEqual(2u, WritingPrimitives.EncodeZigZag64(1));
+            Assert.AreEqual(3u, WritingPrimitives.EncodeZigZag64(-2));
+            Assert.AreEqual(0x000000007FFFFFFEuL,
+                            WritingPrimitives.EncodeZigZag64(unchecked((long) 0x000000003FFFFFFFUL)));
+            Assert.AreEqual(0x000000007FFFFFFFuL,
+                            WritingPrimitives.EncodeZigZag64(unchecked((long) 0xFFFFFFFFC0000000UL)));
+            Assert.AreEqual(0x00000000FFFFFFFEuL,
+                            WritingPrimitives.EncodeZigZag64(unchecked((long) 0x000000007FFFFFFFUL)));
+            Assert.AreEqual(0x00000000FFFFFFFFuL,
+                            WritingPrimitives.EncodeZigZag64(unchecked((long) 0xFFFFFFFF80000000UL)));
+            Assert.AreEqual(0xFFFFFFFFFFFFFFFEL,
+                            WritingPrimitives.EncodeZigZag64(unchecked((long) 0x7FFFFFFFFFFFFFFFUL)));
+            Assert.AreEqual(0xFFFFFFFFFFFFFFFFL,
+                            WritingPrimitives.EncodeZigZag64(unchecked((long) 0x8000000000000000UL)));
+        }
+
+        [Test]
+        public void RoundTripZigZag32()
+        {
+            // Some easier-to-verify round-trip tests.  The inputs (other than 0, 1, -1)
+            // were chosen semi-randomly via keyboard bashing.
+            Assert.AreEqual(0, ParsingPrimitives.DecodeZigZag32(WritingPrimitives.EncodeZigZag32(0)));
+            Assert.AreEqual(1, ParsingPrimitives.DecodeZigZag32(WritingPrimitives.EncodeZigZag32(1)));
+            Assert.AreEqual(-1, ParsingPrimitives.DecodeZigZag32(WritingPrimitives.EncodeZigZag32(-1)));
+            Assert.AreEqual(14927, ParsingPrimitives.DecodeZigZag32(WritingPrimitives.EncodeZigZag32(14927)));
+            Assert.AreEqual(-3612, ParsingPrimitives.DecodeZigZag32(WritingPrimitives.EncodeZigZag32(-3612)));
+        }
+
+        [Test]
+        public void RoundTripZigZag64()
+        {
+            Assert.AreEqual(0, ParsingPrimitives.DecodeZigZag64(WritingPrimitives.EncodeZigZag64(0)));
+            Assert.AreEqual(1, ParsingPrimitives.DecodeZigZag64(WritingPrimitives.EncodeZigZag64(1)));
+            Assert.AreEqual(-1, ParsingPrimitives.DecodeZigZag64(WritingPrimitives.EncodeZigZag64(-1)));
+            Assert.AreEqual(14927, ParsingPrimitives.DecodeZigZag64(WritingPrimitives.EncodeZigZag64(14927)));
+            Assert.AreEqual(-3612, ParsingPrimitives.DecodeZigZag64(WritingPrimitives.EncodeZigZag64(-3612)));
+
+            Assert.AreEqual(856912304801416L,
+                            ParsingPrimitives.DecodeZigZag64(WritingPrimitives.EncodeZigZag64(856912304801416L)));
+            Assert.AreEqual(-75123905439571256L,
+                            ParsingPrimitives.DecodeZigZag64(WritingPrimitives.EncodeZigZag64(-75123905439571256L)));
+        }
+
+        [Test]
+        public void TestNegativeEnumNoTag()
+        {
+            Assert.AreEqual(10, CodedOutputStream.ComputeInt32Size(-2));
+            Assert.AreEqual(10, CodedOutputStream.ComputeEnumSize((int) SampleEnum.NegativeValue));
+
+            byte[] bytes = new byte[10];
+            CodedOutputStream output = new CodedOutputStream(bytes);
+            output.WriteEnum((int) SampleEnum.NegativeValue);
+
+            Assert.AreEqual(0, output.SpaceLeft);
+            Assert.AreEqual("FE-FF-FF-FF-FF-FF-FF-FF-FF-01", BitConverter.ToString(bytes));
+        }
+
+        [Test]
+        public void TestCodedInputOutputPosition()
+        {
+            byte[] content = new byte[110];
+            for (int i = 0; i < content.Length; i++)
+            {
+                content[i] = (byte)i;
+            }
+
+            byte[] child = new byte[120];
+            {
+                MemoryStream ms = new MemoryStream(child);
+                CodedOutputStream cout = new CodedOutputStream(ms, 20);
+                // Field 11: numeric value: 500
+                cout.WriteTag(11, WireFormat.WireType.Varint);
+                Assert.AreEqual(1, cout.Position);
+                cout.WriteInt32(500);
+                Assert.AreEqual(3, cout.Position);
+                //Field 12: length delimited 120 bytes
+                cout.WriteTag(12, WireFormat.WireType.LengthDelimited);
+                Assert.AreEqual(4, cout.Position);
+                cout.WriteBytes(ByteString.CopyFrom(content));
+                Assert.AreEqual(115, cout.Position);
+                // Field 13: fixed numeric value: 501
+                cout.WriteTag(13, WireFormat.WireType.Fixed32);
+                Assert.AreEqual(116, cout.Position);
+                cout.WriteSFixed32(501);
+                Assert.AreEqual(120, cout.Position);
+                cout.Flush();
+            }
+
+            byte[] bytes = new byte[130];
+            {
+                CodedOutputStream cout = new CodedOutputStream(bytes);
+                // Field 1: numeric value: 500
+                cout.WriteTag(1, WireFormat.WireType.Varint);
+                Assert.AreEqual(1, cout.Position);
+                cout.WriteInt32(500);
+                Assert.AreEqual(3, cout.Position);
+                //Field 2: length delimited 120 bytes
+                cout.WriteTag(2, WireFormat.WireType.LengthDelimited);
+                Assert.AreEqual(4, cout.Position);
+                cout.WriteBytes(ByteString.CopyFrom(child));
+                Assert.AreEqual(125, cout.Position);
+                // Field 3: fixed numeric value: 500
+                cout.WriteTag(3, WireFormat.WireType.Fixed32);
+                Assert.AreEqual(126, cout.Position);
+                cout.WriteSFixed32(501);
+                Assert.AreEqual(130, cout.Position);
+                cout.Flush();
+            }
+            // Now test Input stream:
+            {
+                CodedInputStream cin = new CodedInputStream(new MemoryStream(bytes), new byte[50], 0, 0, false);
+                Assert.AreEqual(0, cin.Position);
+                // Field 1:
+                uint tag = cin.ReadTag();
+                Assert.AreEqual(1, tag >> 3);
+                Assert.AreEqual(1, cin.Position);
+                Assert.AreEqual(500, cin.ReadInt32());
+                Assert.AreEqual(3, cin.Position);
+                //Field 2:
+                tag = cin.ReadTag();
+                Assert.AreEqual(2, tag >> 3);
+                Assert.AreEqual(4, cin.Position);
+                int childlen = cin.ReadLength();
+                Assert.AreEqual(120, childlen);
+                Assert.AreEqual(5, cin.Position);
+                int oldlimit = cin.PushLimit((int)childlen);
+                Assert.AreEqual(5, cin.Position);
+                // Now we are reading child message
+                {
+                    // Field 11: numeric value: 500
+                    tag = cin.ReadTag();
+                    Assert.AreEqual(11, tag >> 3);
+                    Assert.AreEqual(6, cin.Position);
+                    Assert.AreEqual(500, cin.ReadInt32());
+                    Assert.AreEqual(8, cin.Position);
+                    //Field 12: length delimited 120 bytes
+                    tag = cin.ReadTag();
+                    Assert.AreEqual(12, tag >> 3);
+                    Assert.AreEqual(9, cin.Position);
+                    ByteString bstr = cin.ReadBytes();
+                    Assert.AreEqual(110, bstr.Length);
+                    Assert.AreEqual((byte) 109, bstr[109]);
+                    Assert.AreEqual(120, cin.Position);
+                    // Field 13: fixed numeric value: 501
+                    tag = cin.ReadTag();
+                    Assert.AreEqual(13, tag >> 3);
+                    // ROK - Previously broken here, this returned 126 failing to account for bufferSizeAfterLimit
+                    Assert.AreEqual(121, cin.Position);
+                    Assert.AreEqual(501, cin.ReadSFixed32());
+                    Assert.AreEqual(125, cin.Position);
+                    Assert.IsTrue(cin.IsAtEnd);
+                }
+                cin.PopLimit(oldlimit);
+                Assert.AreEqual(125, cin.Position);
+                // Field 3: fixed numeric value: 501
+                tag = cin.ReadTag();
+                Assert.AreEqual(3, tag >> 3);
+                Assert.AreEqual(126, cin.Position);
+                Assert.AreEqual(501, cin.ReadSFixed32());
+                Assert.AreEqual(130, cin.Position);
+                Assert.IsTrue(cin.IsAtEnd);
+            }
+        }
+
+        [Test]
+        public void Dispose_DisposesUnderlyingStream()
+        {
+            var memoryStream = new MemoryStream();
+            Assert.IsTrue(memoryStream.CanWrite);
+            using (var cos = new CodedOutputStream(memoryStream))
+            {
+                cos.WriteRawBytes(new byte[] {0});
+                Assert.AreEqual(0, memoryStream.Position); // Not flushed yet
+            }
+            Assert.AreEqual(1, memoryStream.ToArray().Length); // Flushed data from CodedOutputStream to MemoryStream
+            Assert.IsFalse(memoryStream.CanWrite); // Disposed
+        }
+
+        [Test]
+        public void Dispose_WithLeaveOpen()
+        {
+            var memoryStream = new MemoryStream();
+            Assert.IsTrue(memoryStream.CanWrite);
+            using (var cos = new CodedOutputStream(memoryStream, true))
+            {
+                cos.WriteRawBytes(new byte[] {0});
+                Assert.AreEqual(0, memoryStream.Position); // Not flushed yet
+            }
+            Assert.AreEqual(1, memoryStream.Position); // Flushed data from CodedOutputStream to MemoryStream
+            Assert.IsTrue(memoryStream.CanWrite); // We left the stream open
+        }
+
+        [Test]
+        public void Dispose_FromByteArray()
+        {
+            var stream = new CodedOutputStream(new byte[10]);
+            stream.Dispose();
+        }
+
+        [Test]
+        public void WriteString_AsciiSmall_MaxUtf8SizeExceedsBuffer()
+        {
+            var buffer = new byte[5];
+            var output = new CodedOutputStream(buffer);
+            output.WriteString("ABC");
+
+            output.Flush();
+
+            // Verify written content
+            var input = new CodedInputStream(buffer);
+            Assert.AreEqual("ABC", input.ReadString());
+        }
+
+        [Test]
+        public void WriteStringsOfDifferentSizes_Ascii()
+        {
+            for (int i = 1; i <= 1024; i++)
+            {
+                var buffer = new byte[4096];
+                var output = new CodedOutputStream(buffer);
+                var sb = new StringBuilder();
+                for (int j = 0; j < i; j++)
+                {
+                    sb.Append((j % 10).ToString()); // incrementing numbers, repeating
+                }
+                var s = sb.ToString();
+                output.WriteString(s);
+
+                output.Flush();
+
+                // Verify written content
+                var input = new CodedInputStream(buffer);
+                Assert.AreEqual(s, input.ReadString());
+            }
+        }
+
+        [Test]
+        public void WriteStringsOfDifferentSizes_Unicode()
+        {
+            for (int i = 1; i <= 1024; i++)
+            {
+                var buffer = new byte[4096];
+                var output = new CodedOutputStream(buffer);
+                var sb = new StringBuilder();
+                for (int j = 0; j < i; j++)
+                {
+                    char c = (char)((j % 10) + 10112);
+                    sb.Append(c.ToString()); // incrementing unicode numbers, repeating
+                }
+                var s = sb.ToString();
+                output.WriteString(s);
+
+                output.Flush();
+
+                // Verify written content
+                var input = new CodedInputStream(buffer);
+
+                Assert.AreEqual(s, input.ReadString());
+            }
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/Collections/MapFieldTest.cs

@@ -0,0 +1,663 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.IO;
+using System.Collections.Generic;
+using Google.Protobuf.TestProtos;
+using NUnit.Framework;
+using System.Collections;
+using System.Linq;
+
+namespace Google.Protobuf.Collections
+{
+    /// <summary>
+    /// Tests for MapField which aren't reliant on the encoded format -
+    /// tests for serialization/deserialization are part of GeneratedMessageTest.
+    /// </summary>
+    public class MapFieldTest
+    {
+        [Test]
+        public void Clone_ClonesMessages()
+        {
+            var message = new ForeignMessage { C = 20 };
+            var map = new MapField<string, ForeignMessage> { { "x", message } };
+            var clone = map.Clone();
+            map["x"].C = 30;
+            Assert.AreEqual(20, clone["x"].C);
+        }
+
+        [Test]
+        public void NullValuesProhibited()
+        {
+            TestNullValues<int?>(0);
+            TestNullValues("");
+            TestNullValues(new TestAllTypes());
+        }
+
+        private void TestNullValues<T>(T nonNullValue)
+        {
+            var map = new MapField<int, T>();
+            var nullValue = (T) (object) null;
+            Assert.Throws<ArgumentNullException>(() => map.Add(0, nullValue));
+            Assert.Throws<ArgumentNullException>(() => map[0] = nullValue);
+            map.Add(1, nonNullValue);
+            map[1] = nonNullValue;
+        }
+
+        [Test]
+        public void Add_ForbidsNullKeys()
+        {
+            var map = new MapField<string, ForeignMessage>();
+            Assert.Throws<ArgumentNullException>(() => map.Add(null, new ForeignMessage()));
+        }
+
+        [Test]
+        public void Indexer_ForbidsNullKeys()
+        {
+            var map = new MapField<string, ForeignMessage>();
+            Assert.Throws<ArgumentNullException>(() => map[null] = new ForeignMessage());
+        }
+
+        [Test]
+        public void AddPreservesInsertionOrder()
+        {
+            var map = new MapField<string, string>
+            {
+                { "a", "v1" },
+                { "b", "v2" },
+                { "c", "v3" }
+            };
+            map.Remove("b");
+            map.Add("d", "v4");
+            CollectionAssert.AreEqual(new[] { "a", "c", "d" }, map.Keys);
+            CollectionAssert.AreEqual(new[] { "v1", "v3", "v4" }, map.Values);
+        }
+
+        [Test]
+        public void EqualityIsOrderInsensitive()
+        {
+            var map1 = new MapField<string, string>
+            {
+                { "a", "v1" },
+                { "b", "v2" }
+            };
+
+            var map2 = new MapField<string, string>
+            {
+                { "b", "v2" },
+                { "a", "v1" }
+            };
+
+            EqualityTester.AssertEquality(map1, map2);
+        }
+
+        [Test]
+        public void EqualityIsKeySensitive()
+        {
+            var map1 = new MapField<string, string>
+            {
+                { "first key", "v1" },
+                { "second key", "v2" }
+            };
+
+            var map2 = new MapField<string, string>
+            {
+                { "third key", "v1" },
+                { "fourth key", "v2" }
+            };
+
+            EqualityTester.AssertInequality(map1, map2);
+        }
+
+        [Test]
+        public void Equality_Simple()
+        {
+            var map = new MapField<string, string>();
+            EqualityTester.AssertEquality(map, map);
+            EqualityTester.AssertInequality(map, null);
+            Assert.IsFalse(map.Equals(new object()));
+        }
+
+        [Test]
+        public void EqualityIsValueSensitive()
+        {
+            // Note: Without some care, it's a little easier than one might
+            // hope to see hash collisions, but only in some environments...
+            var map1 = new MapField<string, string>
+            {
+                { "a", "first value" },
+                { "b", "second value" }
+            };
+
+            var map2 = new MapField<string, string>
+            {
+                { "a", "third value" },
+                { "b", "fourth value" }
+            };
+
+            EqualityTester.AssertInequality(map1, map2);
+        }
+
+        [Test]
+        public void Add_Dictionary()
+        {
+            var map1 = new MapField<string, string>
+            {
+                { "x", "y" },
+                { "a", "b" }
+            };
+            var map2 = new MapField<string, string>
+            {
+                { "before", "" },
+                map1,
+                { "after", "" }
+            };
+            var expected = new MapField<string, string>
+            {
+                { "before", "" },
+                { "x", "y" },
+                { "a", "b" },
+                { "after", "" }
+            };
+            Assert.AreEqual(expected, map2);
+            CollectionAssert.AreEqual(new[] { "before", "x", "a", "after" }, map2.Keys);
+        }
+
+        // General IDictionary<TKey, TValue> behavior tests
+        [Test]
+        public void Add_KeyAlreadyExists()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" } };
+            Assert.Throws<ArgumentException>(() => map.Add("foo", "baz"));
+        }
+
+        [Test]
+        public void Add_Pair()
+        {
+            var map = new MapField<string, string>();
+            ICollection<KeyValuePair<string, string>> collection = map;
+            collection.Add(NewKeyValuePair("x", "y"));
+            Assert.AreEqual("y", map["x"]);
+            Assert.Throws<ArgumentException>(() => collection.Add(NewKeyValuePair("x", "z")));
+        }
+
+        [Test]
+        public void Contains_Pair()
+        {
+            var map = new MapField<string, string> { { "x", "y" } };
+            ICollection<KeyValuePair<string, string>> collection = map;
+            Assert.IsTrue(collection.Contains(NewKeyValuePair("x", "y")));
+            Assert.IsFalse(collection.Contains(NewKeyValuePair("x", "z")));
+            Assert.IsFalse(collection.Contains(NewKeyValuePair("z", "y")));
+        }
+
+        [Test]
+        public void Remove_Key()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" } };
+            Assert.AreEqual(1, map.Count);
+            Assert.IsFalse(map.Remove("missing"));
+            Assert.AreEqual(1, map.Count);
+            Assert.IsTrue(map.Remove("foo"));
+            Assert.AreEqual(0, map.Count);
+            Assert.Throws<ArgumentNullException>(() => map.Remove(null));
+        }
+
+        [Test]
+        public void Remove_Pair()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" } };
+            ICollection<KeyValuePair<string, string>> collection = map;
+            Assert.AreEqual(1, map.Count);
+            Assert.IsFalse(collection.Remove(NewKeyValuePair("wrong key", "bar")));
+            Assert.AreEqual(1, map.Count);
+            Assert.IsFalse(collection.Remove(NewKeyValuePair("foo", "wrong value")));
+            Assert.AreEqual(1, map.Count);
+            Assert.IsTrue(collection.Remove(NewKeyValuePair("foo", "bar")));
+            Assert.AreEqual(0, map.Count);
+            Assert.Throws<ArgumentException>(() => collection.Remove(new KeyValuePair<string, string>(null, "")));
+        }
+
+        [Test]
+        public void CopyTo_Pair()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" } };
+            ICollection<KeyValuePair<string, string>> collection = map;
+            KeyValuePair<string, string>[] array = new KeyValuePair<string, string>[3];
+            collection.CopyTo(array, 1);
+            Assert.AreEqual(NewKeyValuePair("foo", "bar"), array[1]);
+        }
+
+        [Test]
+        public void Clear()
+        {
+            var map = new MapField<string, string> { { "x", "y" } };
+            Assert.AreEqual(1, map.Count);
+            map.Clear();
+            Assert.AreEqual(0, map.Count);
+            map.Add("x", "y");
+            Assert.AreEqual(1, map.Count);
+        }
+
+        [Test]
+        public void Indexer_Get()
+        {
+            var map = new MapField<string, string> { { "x", "y" } };
+            Assert.AreEqual("y", map["x"]);
+            Assert.Throws<KeyNotFoundException>(() => { var ignored = map["z"]; });
+        }
+
+        [Test]
+        public void Indexer_Set()
+        {
+            var map = new MapField<string, string> { ["x"] = "y" };
+            Assert.AreEqual("y", map["x"]);
+            map["x"] = "z"; // This won't throw, unlike Add.
+            Assert.AreEqual("z", map["x"]);
+        }
+
+        [Test]
+        public void GetEnumerator_NonGeneric()
+        {
+            IEnumerable map = new MapField<string, string> { { "x", "y" } };
+            CollectionAssert.AreEqual(new[] { new KeyValuePair<string, string>("x", "y") },
+                map.Cast<object>().ToList());
+        }
+
+        // Test for the explicitly-implemented non-generic IDictionary interface
+        [Test]
+        public void IDictionary_GetEnumerator()
+        {
+            IDictionary map = new MapField<string, string> { { "x", "y" } };
+            var enumerator = map.GetEnumerator();
+
+            // Commented assertions show an ideal situation - it looks like
+            // the LinkedList enumerator doesn't throw when you ask for the current entry
+            // at an inappropriate time; fixing this would be more work than it's worth.
+            // Assert.Throws<InvalidOperationException>(() => enumerator.Current.GetHashCode());
+            Assert.IsTrue(enumerator.MoveNext());
+            Assert.AreEqual("x", enumerator.Key);
+            Assert.AreEqual("y", enumerator.Value);
+            Assert.AreEqual(new DictionaryEntry("x", "y"), enumerator.Current);
+            Assert.AreEqual(new DictionaryEntry("x", "y"), enumerator.Entry);
+            Assert.IsFalse(enumerator.MoveNext());
+            // Assert.Throws<InvalidOperationException>(() => enumerator.Current.GetHashCode());
+            enumerator.Reset();
+            // Assert.Throws<InvalidOperationException>(() => enumerator.Current.GetHashCode());
+            Assert.IsTrue(enumerator.MoveNext());
+            Assert.AreEqual("x", enumerator.Key); // Assume the rest are okay
+        }
+
+        [Test]
+        public void IDictionary_Add()
+        {
+            var map = new MapField<string, string> { { "x", "y" } };
+            IDictionary dictionary = map;
+            dictionary.Add("a", "b");
+            Assert.AreEqual("b", map["a"]);
+            Assert.Throws<ArgumentException>(() => dictionary.Add("a", "duplicate"));
+            Assert.Throws<InvalidCastException>(() => dictionary.Add(new object(), "key is bad"));
+            Assert.Throws<InvalidCastException>(() => dictionary.Add("value is bad", new object()));
+        }
+
+        [Test]
+        public void IDictionary_Contains()
+        {
+            var map = new MapField<string, string> { { "x", "y" } };
+            IDictionary dictionary = map;
+
+            Assert.IsFalse(dictionary.Contains("a"));
+            Assert.IsFalse(dictionary.Contains(5));
+            // Surprising, but IDictionary.Contains is only about keys.
+            Assert.IsFalse(dictionary.Contains(new DictionaryEntry("x", "y")));
+            Assert.IsTrue(dictionary.Contains("x"));
+        }
+
+        [Test]
+        public void IDictionary_Remove()
+        {
+            var map = new MapField<string, string> { { "x", "y" } };
+            IDictionary dictionary = map;
+            dictionary.Remove("a");
+            Assert.AreEqual(1, dictionary.Count);
+            dictionary.Remove(5);
+            Assert.AreEqual(1, dictionary.Count);
+            dictionary.Remove(new DictionaryEntry("x", "y"));
+            Assert.AreEqual(1, dictionary.Count);
+            dictionary.Remove("x");
+            Assert.AreEqual(0, dictionary.Count);
+            Assert.Throws<ArgumentNullException>(() => dictionary.Remove(null));
+        }
+
+        [Test]
+        public void IDictionary_CopyTo()
+        {
+            var map = new MapField<string, string> { { "x", "y" } };
+            IDictionary dictionary = map;
+            var array = new DictionaryEntry[3];
+            dictionary.CopyTo(array, 1);
+            CollectionAssert.AreEqual(new[] { default, new DictionaryEntry("x", "y"), default }, array);
+            var objectArray = new object[3];
+            dictionary.CopyTo(objectArray, 1);
+            CollectionAssert.AreEqual(new object[] { null, new DictionaryEntry("x", "y"), null }, objectArray);
+        }
+
+        [Test]
+        public void IDictionary_IsFixedSize()
+        {
+            var map = new MapField<string, string> { { "x", "y" } };
+            IDictionary dictionary = map;
+            Assert.IsFalse(dictionary.IsFixedSize);
+        }
+
+        [Test]
+        public void IDictionary_Keys()
+        {
+            IDictionary dictionary = new MapField<string, string> { { "x", "y" } };
+            CollectionAssert.AreEqual(new[] { "x" }, dictionary.Keys);
+        }
+
+        [Test]
+        public void IDictionary_Values()
+        {
+            IDictionary dictionary = new MapField<string, string> { { "x", "y" } };
+            CollectionAssert.AreEqual(new[] { "y" }, dictionary.Values);
+        }
+
+        [Test]
+        public void IDictionary_IsSynchronized()
+        {
+            IDictionary dictionary = new MapField<string, string> { { "x", "y" } };
+            Assert.IsFalse(dictionary.IsSynchronized);
+        }
+
+        [Test]
+        public void IDictionary_SyncRoot()
+        {
+            IDictionary dictionary = new MapField<string, string> { { "x", "y" } };
+            Assert.AreSame(dictionary, dictionary.SyncRoot);
+        }
+
+        [Test]
+        public void IDictionary_Indexer_Get()
+        {
+            IDictionary dictionary = new MapField<string, string> { { "x", "y" } };
+            Assert.AreEqual("y", dictionary["x"]);
+            Assert.IsNull(dictionary["a"]);
+            Assert.IsNull(dictionary[5]);
+            Assert.Throws<ArgumentNullException>(() => dictionary[null].GetHashCode());
+        }
+
+        [Test]
+        public void IDictionary_Indexer_Set()
+        {
+            var map = new MapField<string, string> { { "x", "y" } };
+            IDictionary dictionary = map;
+            map["a"] = "b";
+            Assert.AreEqual("b", map["a"]);
+            map["a"] = "c";
+            Assert.AreEqual("c", map["a"]);
+            Assert.Throws<InvalidCastException>(() => dictionary[5] = "x");
+            Assert.Throws<InvalidCastException>(() => dictionary["x"] = 5);
+            Assert.Throws<ArgumentNullException>(() => dictionary[null] = "z");
+            Assert.Throws<ArgumentNullException>(() => dictionary["x"] = null);
+        }
+
+        [Test]
+        public void KeysReturnsLiveView()
+        {
+            var map = new MapField<string, string>();
+            var keys = map.Keys;
+            CollectionAssert.AreEqual(new string[0], keys);
+            map["foo"] = "bar";
+            map["x"] = "y";
+            CollectionAssert.AreEqual(new[] { "foo", "x" }, keys);
+        }
+
+        [Test]
+        public void ValuesReturnsLiveView()
+        {
+            var map = new MapField<string, string>();
+            var values = map.Values;
+            CollectionAssert.AreEqual(new string[0], values);
+            map["foo"] = "bar";
+            map["x"] = "y";
+            CollectionAssert.AreEqual(new[] { "bar", "y" }, values);
+        }
+
+        // Just test keys - we know the implementation is the same for values
+        [Test]
+        public void ViewsAreReadOnly()
+        {
+            var map = new MapField<string, string>();
+            var keys = map.Keys;
+            Assert.IsTrue(keys.IsReadOnly);
+            Assert.Throws<NotSupportedException>(() => keys.Clear());
+            Assert.Throws<NotSupportedException>(() => keys.Remove("a"));
+            Assert.Throws<NotSupportedException>(() => keys.Add("a"));
+        }
+
+        // Just test keys - we know the implementation is the same for values
+        [Test]
+        public void ViewCopyTo()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" }, { "x", "y" } };
+            var keys = map.Keys;
+            var array = new string[4];
+            Assert.Throws<ArgumentException>(() => keys.CopyTo(array, 3));
+            Assert.Throws<ArgumentOutOfRangeException>(() => keys.CopyTo(array, -1));
+            keys.CopyTo(array, 1);
+            CollectionAssert.AreEqual(new[] { null, "foo", "x", null }, array);
+        }
+
+        // Just test keys - we know the implementation is the same for values
+        [Test]
+        public void NonGenericViewCopyTo()
+        {
+            IDictionary map = new MapField<string, string> { { "foo", "bar" }, { "x", "y" } };
+            ICollection keys = map.Keys;
+            // Note the use of the Array type here rather than string[]
+            Array array = new string[4];
+            Assert.Throws<ArgumentException>(() => keys.CopyTo(array, 3));
+            Assert.Throws<ArgumentOutOfRangeException>(() => keys.CopyTo(array, -1));
+            keys.CopyTo(array, 1);
+            CollectionAssert.AreEqual(new[] { null, "foo", "x", null }, array);
+        }
+
+        [Test]
+        public void KeysContains()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" }, { "x", "y" } };
+            var keys = map.Keys;
+            Assert.IsTrue(keys.Contains("foo"));
+            Assert.IsFalse(keys.Contains("bar")); // It's a value!
+            Assert.IsFalse(keys.Contains("1"));
+            // Keys can't be null, so we should prevent contains check
+            Assert.Throws<ArgumentNullException>(() => keys.Contains(null));
+        }
+
+        [Test]
+        public void KeysCopyTo()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" }, { "x", "y" } };
+            var keys = map.Keys.ToArray(); // Uses CopyTo internally
+            CollectionAssert.AreEquivalent(new[] { "foo", "x" }, keys);
+        }
+
+        [Test]
+        public void ValuesContains()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" }, { "x", "y" } };
+            var values = map.Values;
+            Assert.IsTrue(values.Contains("bar"));
+            Assert.IsFalse(values.Contains("foo")); // It's a key!
+            Assert.IsFalse(values.Contains("1"));
+            // Values can be null, so this makes sense
+            Assert.IsFalse(values.Contains(null));
+        }
+
+        [Test]
+        public void ValuesCopyTo()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" }, { "x", "y" } };
+            var values = map.Values.ToArray(); // Uses CopyTo internally
+            CollectionAssert.AreEquivalent(new[] { "bar", "y" }, values);
+        }
+
+        [Test]
+        public void ToString_StringToString()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" }, { "x", "y" } };
+            Assert.AreEqual("{ \"foo\": \"bar\", \"x\": \"y\" }", map.ToString());
+        }
+
+        [Test]
+        public void ToString_UnsupportedKeyType()
+        {
+            var map = new MapField<byte, string> { { 10, "foo" } };
+            Assert.Throws<ArgumentException>(() => map.ToString());
+        }
+
+        [Test]
+        public void NaNValuesComparedBitwise()
+        {
+            var map1 = new MapField<string, double>
+            {
+                { "x", SampleNaNs.Regular },
+                { "y", SampleNaNs.SignallingFlipped }
+            };
+
+            var map2 = new MapField<string, double>
+            {
+                { "x", SampleNaNs.Regular },
+                { "y", SampleNaNs.PayloadFlipped }
+            };
+
+            var map3 = new MapField<string, double>
+            {
+                { "x", SampleNaNs.Regular },
+                { "y", SampleNaNs.SignallingFlipped }
+            };
+
+            EqualityTester.AssertInequality(map1, map2);
+            EqualityTester.AssertEquality(map1, map3);
+            Assert.True(map1.Values.Contains(SampleNaNs.SignallingFlipped));
+            Assert.False(map2.Values.Contains(SampleNaNs.SignallingFlipped));
+        }
+
+        // This wouldn't usually happen, as protos can't use doubles as map keys,
+        // but let's be consistent.
+        [Test]
+        public void NaNKeysComparedBitwise()
+        {
+            var map = new MapField<double, string>
+            {
+                { SampleNaNs.Regular, "x" },
+                { SampleNaNs.SignallingFlipped, "y" }
+            };
+            Assert.AreEqual("x", map[SampleNaNs.Regular]);
+            Assert.AreEqual("y", map[SampleNaNs.SignallingFlipped]);
+            Assert.False(map.TryGetValue(SampleNaNs.PayloadFlipped, out _));
+        }
+
+        [Test]
+        public void AddEntriesFrom_CodedInputStream()
+        {
+            // map will have string key and string value
+            var keyTag = WireFormat.MakeTag(1, WireFormat.WireType.LengthDelimited);
+            var valueTag = WireFormat.MakeTag(2, WireFormat.WireType.LengthDelimited);
+
+            var memoryStream = new MemoryStream();
+            var output = new CodedOutputStream(memoryStream);
+            output.WriteLength(20);  // total of keyTag + key + valueTag + value
+            output.WriteTag(keyTag);
+            output.WriteString("the_key");
+            output.WriteTag(valueTag);
+            output.WriteString("the_value");
+            output.Flush();
+
+            var field = new MapField<string,string>();
+            var mapCodec = new MapField<string,string>.Codec(FieldCodec.ForString(keyTag, ""), FieldCodec.ForString(valueTag, ""), 10);
+            var input = new CodedInputStream(memoryStream.ToArray());
+
+            // test the legacy overload of AddEntriesFrom that takes a CodedInputStream
+            field.AddEntriesFrom(input, mapCodec);
+            CollectionAssert.AreEquivalent(new[] { "the_key" }, field.Keys);
+            CollectionAssert.AreEquivalent(new[] { "the_value" }, field.Values);
+            Assert.IsTrue(input.IsAtEnd);
+        }
+
+        [Test]
+        public void AddEntriesFrom_CodedInputStream_MissingKey()
+        {
+            // map will have string key and string value
+            var keyTag = WireFormat.MakeTag(1, WireFormat.WireType.LengthDelimited);
+            var valueTag = WireFormat.MakeTag(2, WireFormat.WireType.LengthDelimited);
+
+            var memoryStream = new MemoryStream();
+            var output = new CodedOutputStream(memoryStream);
+            output.WriteLength(11);  // total of valueTag + value
+            output.WriteTag(valueTag);
+            output.WriteString("the_value");
+            output.Flush();
+
+            var field = new MapField<string, string>();
+            var mapCodec = new MapField<string, string>.Codec(FieldCodec.ForString(keyTag, ""), FieldCodec.ForString(valueTag, ""), 10);
+            var input = new CodedInputStream(memoryStream.ToArray());
+
+            field.AddEntriesFrom(input, mapCodec);
+            CollectionAssert.AreEquivalent(new[] { "" }, field.Keys);
+            CollectionAssert.AreEquivalent(new[] { "the_value" }, field.Values);
+            Assert.IsTrue(input.IsAtEnd);
+        }
+
+        [Test]
+        public void IDictionaryKeys_Equals_IReadOnlyDictionaryKeys()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" }, { "x", "y" } };
+            CollectionAssert.AreEquivalent(((IDictionary<string, string>)map).Keys, ((IReadOnlyDictionary<string, string>)map).Keys);
+        }
+
+        [Test]
+        public void IDictionaryValues_Equals_IReadOnlyDictionaryValues()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" }, { "x", "y" } };
+            CollectionAssert.AreEquivalent(((IDictionary<string, string>)map).Values, ((IReadOnlyDictionary<string, string>)map).Values);
+        }
+
+        private static KeyValuePair<TKey, TValue> NewKeyValuePair<TKey, TValue>(TKey key, TValue value)
+        {
+            return new KeyValuePair<TKey, TValue>(key, value);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/Collections/ProtobufEqualityComparersTest.cs

@@ -0,0 +1,124 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2017 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using NUnit.Framework;
+using System.Collections.Generic;
+using System.Linq;
+using static Google.Protobuf.Collections.ProtobufEqualityComparers;
+
+namespace Google.Protobuf.Collections
+{
+    public class ProtobufEqualityComparersTest
+    {
+        private static readonly double[] doubles =
+        {
+            0,
+            1,
+            1.5,
+            -1.5,
+            double.PositiveInfinity,
+            double.NegativeInfinity,
+            // Three different types of NaN...
+            SampleNaNs.Regular,
+            SampleNaNs.SignallingFlipped,
+            SampleNaNs.PayloadFlipped
+        };
+
+        [Test]
+        public void GetEqualityComparer_Default()
+        {
+            // It's more pain than it's worth to try to parameterize these tests.
+            Assert.AreSame(EqualityComparer<object>.Default, GetEqualityComparer<object>());
+            Assert.AreSame(EqualityComparer<string>.Default, GetEqualityComparer<string>());
+            Assert.AreSame(EqualityComparer<int>.Default, GetEqualityComparer<int>());
+            Assert.AreSame(EqualityComparer<int?>.Default, GetEqualityComparer<int?>());
+        }
+
+        [Test]
+        public void GetEqualityComparer_NotDefault()
+        {
+            // It's more pain than it's worth to try to parameterize these tests.
+            Assert.AreSame(BitwiseDoubleEqualityComparer, GetEqualityComparer<double>());
+            Assert.AreSame(BitwiseSingleEqualityComparer, GetEqualityComparer<float>());
+            Assert.AreSame(BitwiseNullableDoubleEqualityComparer, GetEqualityComparer<double?>());
+            Assert.AreSame(BitwiseNullableSingleEqualityComparer, GetEqualityComparer<float?>());
+        }
+
+        [Test]
+        public void DoubleComparisons()
+        {
+            ValidateEqualityComparer(BitwiseDoubleEqualityComparer, doubles);
+        }
+
+        [Test]
+        public void NullableDoubleComparisons()
+        {
+            ValidateEqualityComparer(BitwiseNullableDoubleEqualityComparer, doubles.Select(d => (double?) d).Concat(new double?[] { null }));
+        }
+
+        [Test]
+        public void SingleComparisons()
+        {
+            ValidateEqualityComparer(BitwiseSingleEqualityComparer, doubles.Select(d => (float) d));
+        }
+
+        [Test]
+        public void NullableSingleComparisons()
+        {
+            ValidateEqualityComparer(BitwiseNullableSingleEqualityComparer, doubles.Select(d => (float?) d).Concat(new float?[] { null }));
+        }
+
+        private static void ValidateEqualityComparer<T>(EqualityComparer<T> comparer, IEnumerable<T> values)
+        {
+            var array = values.ToArray();
+            // Each value should be equal to itself, but not to any other value.
+            for (int i = 0; i < array.Length; i++)
+            {
+                for (int j = 0; j < array.Length; j++)
+                {
+                    if (i == j)
+                    {
+                        Assert.IsTrue(comparer.Equals(array[i], array[j]),
+                            "{0} should be equal to itself", array[i], array[j]);
+                    }
+                    else
+                    {
+                        Assert.IsFalse(comparer.Equals(array[i], array[j]),
+                            "{0} and {1} should not be equal", array[i], array[j]);
+                        Assert.AreNotEqual(comparer.GetHashCode(array[i]), comparer.GetHashCode(array[j]),
+                            "Hash codes for {0} and {1} should not be equal", array[i], array[j]);
+                    }
+                }
+            }
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/Collections/RepeatedFieldTest.cs

@@ -0,0 +1,904 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using Google.Protobuf.TestProtos;
+using Google.Protobuf.WellKnownTypes;
+using NUnit.Framework;
+
+namespace Google.Protobuf.Collections
+{
+    public class RepeatedFieldTest
+    {
+        [Test]
+        public void NullValuesRejected()
+        {
+            var list = new RepeatedField<string>();
+            Assert.Throws<ArgumentNullException>(() => list.Add((string)null));
+            Assert.Throws<ArgumentNullException>(() => list.Add((IEnumerable<string>)null));
+            Assert.Throws<ArgumentNullException>(() => list.Add((RepeatedField<string>)null));
+            Assert.Throws<ArgumentNullException>(() => list.Contains(null));
+            Assert.Throws<ArgumentNullException>(() => list.IndexOf(null));
+        }
+
+        [Test]
+        public void Add_SingleItem()
+        {
+            var list = new RepeatedField<string> { "foo" };
+            Assert.AreEqual(1, list.Count);
+            Assert.AreEqual("foo", list[0]);
+        }
+
+        [Test]
+        public void Add_Sequence()
+        {
+            var list = new RepeatedField<string> { new[] { "foo", "bar" } };
+            Assert.AreEqual(2, list.Count);
+            Assert.AreEqual("foo", list[0]);
+            Assert.AreEqual("bar", list[1]);
+        }
+
+        [Test]
+        public void AddRange_SlowPath()
+        {
+            var list = new RepeatedField<string>();
+            list.AddRange(new[] { "foo", "bar" }.Select(x => x));
+            Assert.AreEqual(2, list.Count);
+            Assert.AreEqual("foo", list[0]);
+            Assert.AreEqual("bar", list[1]);
+        }
+
+        [Test]
+        public void AddRange_SlowPath_NullsProhibited_ReferenceType()
+        {
+            var list = new RepeatedField<string>();
+            // It's okay for this to throw ArgumentNullException if necessary.
+            // It's not ideal, but not awful.
+            Assert.Catch<ArgumentException>(() => list.AddRange(new[] { "foo", null }.Select(x => x)));
+        }
+
+        [Test]
+        public void AddRange_SlowPath_NullsProhibited_NullableValueType()
+        {
+            var list = new RepeatedField<int?>();
+            // It's okay for this to throw ArgumentNullException if necessary.
+            // It's not ideal, but not awful.
+            Assert.Catch<ArgumentException>(() => list.AddRange(new[] { 20, (int?)null }.Select(x => x)));
+        }
+
+        [Test]
+        public void AddRange_Optimized_NonNullableValueType()
+        {
+            var list = new RepeatedField<int>();
+            list.AddRange(new List<int> { 20, 30 });
+            Assert.AreEqual(2, list.Count);
+            Assert.AreEqual(20, list[0]);
+            Assert.AreEqual(30, list[1]);
+        }
+
+        [Test]
+        public void AddRange_Optimized_ReferenceType()
+        {
+            var list = new RepeatedField<string>();
+            list.AddRange(new List<string> { "foo", "bar" });
+            Assert.AreEqual(2, list.Count);
+            Assert.AreEqual("foo", list[0]);
+            Assert.AreEqual("bar", list[1]);
+        }
+
+        [Test]
+        public void AddRange_Optimized_NullableValueType()
+        {
+            var list = new RepeatedField<int?>();
+            list.AddRange(new List<int?> { 20, 30 });
+            Assert.AreEqual(2, list.Count);
+            Assert.AreEqual((int?) 20, list[0]);
+            Assert.AreEqual((int?) 30, list[1]);
+        }
+
+        [Test]
+        public void AddRange_Optimized_NullsProhibited_ReferenceType()
+        {
+            // We don't just trust that a collection with a nullable element type doesn't contain nulls
+            var list = new RepeatedField<string>();
+            // It's okay for this to throw ArgumentNullException if necessary.
+            // It's not ideal, but not awful.
+            Assert.Catch<ArgumentException>(() => list.AddRange(new List<string> { "foo", null }));
+        }
+
+        [Test]
+        public void AddRange_Optimized_NullsProhibited_NullableValueType()
+        {
+            // We don't just trust that a collection with a nullable element type doesn't contain nulls
+            var list = new RepeatedField<int?>();
+            // It's okay for this to throw ArgumentNullException if necessary.
+            // It's not ideal, but not awful.
+            Assert.Catch<ArgumentException>(() => list.AddRange(new List<int?> { 20, null }));
+        }
+
+        [Test]
+        public void AddRange_AlreadyNotEmpty()
+        {
+            var list = new RepeatedField<int> { 1, 2, 3 };
+            list.AddRange(new List<int> { 4, 5, 6 });
+            CollectionAssert.AreEqual(new[] { 1, 2, 3, 4, 5, 6 }, list);
+        }
+
+        [Test]
+        public void AddRange_RepeatedField()
+        {
+            var list = new RepeatedField<string> { "original" };
+            list.AddRange(new RepeatedField<string> { "foo", "bar" });
+            Assert.AreEqual(3, list.Count);
+            Assert.AreEqual("original", list[0]);
+            Assert.AreEqual("foo", list[1]);
+            Assert.AreEqual("bar", list[2]);
+        }
+
+        [Test]
+        public void RemoveAt_Valid()
+        {
+            var list = new RepeatedField<string> { "first", "second", "third" };
+            list.RemoveAt(1);
+            CollectionAssert.AreEqual(new[] { "first", "third" }, list);
+            // Just check that these don't throw...
+            list.RemoveAt(list.Count - 1); // Now the count will be 1...
+            list.RemoveAt(0);
+            Assert.AreEqual(0, list.Count);
+        }
+
+        [Test]
+        public void RemoveAt_Invalid()
+        {
+            var list = new RepeatedField<string> { "first", "second", "third" };
+            Assert.Throws<ArgumentOutOfRangeException>(() => list.RemoveAt(-1));
+            Assert.Throws<ArgumentOutOfRangeException>(() => list.RemoveAt(3));
+        }
+
+        [Test]
+        public void Insert_Valid()
+        {
+            var list = new RepeatedField<string> { "first", "second" };
+            list.Insert(1, "middle");
+            CollectionAssert.AreEqual(new[] { "first", "middle", "second" }, list);
+            list.Insert(3, "end");
+            CollectionAssert.AreEqual(new[] { "first", "middle", "second", "end" }, list);
+            list.Insert(0, "start");
+            CollectionAssert.AreEqual(new[] { "start", "first", "middle", "second", "end" }, list);
+        }
+
+        [Test]
+        public void Insert_Invalid()
+        {
+            var list = new RepeatedField<string> { "first", "second" };
+            Assert.Throws<ArgumentOutOfRangeException>(() => list.Insert(-1, "foo"));
+            Assert.Throws<ArgumentOutOfRangeException>(() => list.Insert(3, "foo"));
+            Assert.Throws<ArgumentNullException>(() => list.Insert(0, null));
+        }
+
+        [Test]
+        public void Equals_RepeatedField()
+        {
+            var list = new RepeatedField<string> { "first", "second" };
+            Assert.IsFalse(list.Equals((RepeatedField<string>) null));
+            Assert.IsTrue(list.Equals(list));
+            Assert.IsFalse(list.Equals(new RepeatedField<string> { "first", "third" }));
+            Assert.IsFalse(list.Equals(new RepeatedField<string> { "first" }));
+            Assert.IsTrue(list.Equals(new RepeatedField<string> { "first", "second" }));
+        }
+
+        [Test]
+        public void Equals_Object()
+        {
+            var list = new RepeatedField<string> { "first", "second" };
+            Assert.IsFalse(list.Equals((object) null));
+            Assert.IsTrue(list.Equals((object) list));
+            Assert.IsFalse(list.Equals((object) new RepeatedField<string> { "first", "third" }));
+            Assert.IsFalse(list.Equals((object) new RepeatedField<string> { "first" }));
+            Assert.IsTrue(list.Equals((object) new RepeatedField<string> { "first", "second" }));
+            Assert.IsFalse(list.Equals(new object()));
+        }
+
+        [Test]
+        public void GetEnumerator_GenericInterface()
+        {
+            IEnumerable<string> list = new RepeatedField<string> { "first", "second" };
+            // Select gets rid of the optimizations in ToList...
+            CollectionAssert.AreEqual(new[] { "first", "second" }, list.Select(x => x).ToList());
+        }
+
+        [Test]
+        public void GetEnumerator_NonGenericInterface()
+        {
+            IEnumerable list = new RepeatedField<string> { "first", "second" };
+            CollectionAssert.AreEqual(new[] { "first", "second" }, list.Cast<object>().ToList());
+        }
+
+        [Test]
+        public void CopyTo()
+        {
+            var list = new RepeatedField<string> { "first", "second" };
+            string[] stringArray = new string[4];
+            list.CopyTo(stringArray, 1);
+            CollectionAssert.AreEqual(new[] { null, "first", "second", null }, stringArray);
+        }
+
+        [Test]
+        public void Indexer_Get()
+        {
+            var list = new RepeatedField<string> { "first", "second" };
+            Assert.AreEqual("first", list[0]);
+            Assert.AreEqual("second", list[1]);
+            Assert.Throws<ArgumentOutOfRangeException>(() => list[-1].GetHashCode());
+            Assert.Throws<ArgumentOutOfRangeException>(() => list[2].GetHashCode());
+        }
+
+        [Test]
+        public void Indexer_Set()
+        {
+            var list = new RepeatedField<string> { "first", "second" };
+            list[0] = "changed";
+            Assert.AreEqual("changed", list[0]);
+            Assert.Throws<ArgumentNullException>(() => list[0] = null);
+            Assert.Throws<ArgumentOutOfRangeException>(() => list[-1] = "bad");
+            Assert.Throws<ArgumentOutOfRangeException>(() => list[2] = "bad");
+        }
+
+        [Test]
+        public void Clone_ReturnsMutable()
+        {
+            var list = new RepeatedField<int> { 0 };
+            var clone = list.Clone();
+            clone[0] = 1;
+        }
+
+        [Test]
+        public void Enumerator()
+        {
+            var list = new RepeatedField<string> { "first", "second" };
+            using var enumerator = list.GetEnumerator();
+            Assert.IsTrue(enumerator.MoveNext());
+            Assert.AreEqual("first", enumerator.Current);
+            Assert.IsTrue(enumerator.MoveNext());
+            Assert.AreEqual("second", enumerator.Current);
+            Assert.IsFalse(enumerator.MoveNext());
+            Assert.IsFalse(enumerator.MoveNext());
+        }
+
+        [Test]
+        public void AddEntriesFrom_PackedInt32()
+        {
+            uint packedTag = WireFormat.MakeTag(10, WireFormat.WireType.LengthDelimited);
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            var length = CodedOutputStream.ComputeInt32Size(10)
+                + CodedOutputStream.ComputeInt32Size(999)
+                + CodedOutputStream.ComputeInt32Size(-1000);
+            output.WriteTag(packedTag);
+            output.WriteRawVarint32((uint) length);
+            output.WriteInt32(10);
+            output.WriteInt32(999);
+            output.WriteInt32(-1000);
+            output.Flush();
+            stream.Position = 0;
+
+            // Deliberately "expecting" a non-packed tag, but we detect that the data is
+            // actually packed.
+            uint nonPackedTag = WireFormat.MakeTag(10, WireFormat.WireType.LengthDelimited);
+            var field = new RepeatedField<int>();
+            var input = new CodedInputStream(stream);
+            input.AssertNextTag(packedTag);
+            field.AddEntriesFrom(input, FieldCodec.ForInt32(nonPackedTag));
+            CollectionAssert.AreEqual(new[] { 10, 999, -1000 }, field);
+            Assert.IsTrue(input.IsAtEnd);
+        }
+
+        [Test]
+        public void AddEntriesFrom_NonPackedInt32()
+        {
+            uint nonPackedTag = WireFormat.MakeTag(10, WireFormat.WireType.Varint);
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            output.WriteTag(nonPackedTag);
+            output.WriteInt32(10);
+            output.WriteTag(nonPackedTag);
+            output.WriteInt32(999);
+            output.WriteTag(nonPackedTag);
+            output.WriteInt32(-1000); // Just for variety...
+            output.Flush();
+            stream.Position = 0;
+
+            // Deliberately "expecting" a packed tag, but we detect that the data is
+            // actually not packed.
+            uint packedTag = WireFormat.MakeTag(10, WireFormat.WireType.LengthDelimited);
+            var field = new RepeatedField<int>();
+            var input = new CodedInputStream(stream);
+            input.AssertNextTag(nonPackedTag);
+            field.AddEntriesFrom(input, FieldCodec.ForInt32(packedTag));
+            CollectionAssert.AreEqual(new[] { 10, 999, -1000 }, field);
+            Assert.IsTrue(input.IsAtEnd);
+        }
+
+        [Test]
+        public void AddEntriesFrom_String()
+        {
+            uint tag = WireFormat.MakeTag(10, WireFormat.WireType.LengthDelimited);
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            output.WriteTag(tag);
+            output.WriteString("Foo");
+            output.WriteTag(tag);
+            output.WriteString("");
+            output.WriteTag(tag);
+            output.WriteString("Bar");
+            output.Flush();
+            stream.Position = 0;
+
+            var field = new RepeatedField<string>();
+            var input = new CodedInputStream(stream);
+            input.AssertNextTag(tag);
+            field.AddEntriesFrom(input, FieldCodec.ForString(tag));
+            CollectionAssert.AreEqual(new[] { "Foo", "", "Bar" }, field);
+            Assert.IsTrue(input.IsAtEnd);
+        }
+
+        [Test]
+        public void AddEntriesFrom_Message()
+        {
+            var message1 = new ForeignMessage { C = 2000 };
+            var message2 = new ForeignMessage { C = -250 };
+
+            uint tag = WireFormat.MakeTag(10, WireFormat.WireType.LengthDelimited);
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            output.WriteTag(tag);
+            output.WriteMessage(message1);
+            output.WriteTag(tag);
+            output.WriteMessage(message2);
+            output.Flush();
+            stream.Position = 0;
+
+            var field = new RepeatedField<ForeignMessage>();
+            var input = new CodedInputStream(stream);
+            input.AssertNextTag(tag);
+            field.AddEntriesFrom(input, FieldCodec.ForMessage(tag, ForeignMessage.Parser));
+            CollectionAssert.AreEqual(new[] { message1, message2}, field);
+            Assert.IsTrue(input.IsAtEnd);
+        }
+
+        [Test]
+        public void WriteTo_PackedInt32()
+        {
+            uint tag = WireFormat.MakeTag(10, WireFormat.WireType.LengthDelimited);
+            var field = new RepeatedField<int> { 10, 1000, 1000000 };
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            field.WriteTo(output, FieldCodec.ForInt32(tag));
+            output.Flush();
+            stream.Position = 0;
+
+            var input = new CodedInputStream(stream);
+            input.AssertNextTag(tag);
+            var length = input.ReadLength();
+            Assert.AreEqual(10, input.ReadInt32());
+            Assert.AreEqual(1000, input.ReadInt32());
+            Assert.AreEqual(1000000, input.ReadInt32());
+            Assert.IsTrue(input.IsAtEnd);
+            Assert.AreEqual(1 + CodedOutputStream.ComputeLengthSize(length) + length, stream.Length);
+        }
+
+        [Test]
+        public void WriteTo_NonPackedInt32()
+        {
+            uint tag = WireFormat.MakeTag(10, WireFormat.WireType.Varint);
+            var field = new RepeatedField<int> { 10, 1000, 1000000};
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            field.WriteTo(output, FieldCodec.ForInt32(tag));
+            output.Flush();
+            stream.Position = 0;
+
+            var input = new CodedInputStream(stream);
+            input.AssertNextTag(tag);
+            Assert.AreEqual(10, input.ReadInt32());
+            input.AssertNextTag(tag);
+            Assert.AreEqual(1000, input.ReadInt32());
+            input.AssertNextTag(tag);
+            Assert.AreEqual(1000000, input.ReadInt32());
+            Assert.IsTrue(input.IsAtEnd);
+        }
+
+        [Test]
+        public void WriteTo_String()
+        {
+            uint tag = WireFormat.MakeTag(10, WireFormat.WireType.LengthDelimited);
+            var field = new RepeatedField<string> { "Foo", "", "Bar" };
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            field.WriteTo(output, FieldCodec.ForString(tag));
+            output.Flush();
+            stream.Position = 0;
+
+            var input = new CodedInputStream(stream);
+            input.AssertNextTag(tag);
+            Assert.AreEqual("Foo", input.ReadString());
+            input.AssertNextTag(tag);
+            Assert.AreEqual("", input.ReadString());
+            input.AssertNextTag(tag);
+            Assert.AreEqual("Bar", input.ReadString());
+            Assert.IsTrue(input.IsAtEnd);
+        }
+
+        [Test]
+        public void WriteTo_Message()
+        {
+            var message1 = new ForeignMessage { C = 20 };
+            var message2 = new ForeignMessage { C = 25 };
+            uint tag = WireFormat.MakeTag(10, WireFormat.WireType.LengthDelimited);
+            var field = new RepeatedField<ForeignMessage> { message1, message2 };
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            field.WriteTo(output, FieldCodec.ForMessage(tag, ForeignMessage.Parser));
+            output.Flush();
+            stream.Position = 0;
+
+            var input = new CodedInputStream(stream);
+            input.AssertNextTag(tag);
+            Assert.AreEqual(message1, input.ReadMessage(ForeignMessage.Parser));
+            input.AssertNextTag(tag);
+            Assert.AreEqual(message2, input.ReadMessage(ForeignMessage.Parser));
+            Assert.IsTrue(input.IsAtEnd);
+        }
+
+        [Test]
+        public void CalculateSize_VariableSizeNonPacked()
+        {
+            var list = new RepeatedField<int> { 1, 500, 1 };
+            var tag = WireFormat.MakeTag(1, WireFormat.WireType.Varint);
+            // 2 bytes for the first entry, 3 bytes for the second, 2 bytes for the third
+            Assert.AreEqual(7, list.CalculateSize(FieldCodec.ForInt32(tag)));
+        }
+
+        [Test]
+        public void CalculateSize_FixedSizeNonPacked()
+        {
+            var list = new RepeatedField<int> { 1, 500, 1 };
+            var tag = WireFormat.MakeTag(1, WireFormat.WireType.Fixed32);
+            // 5 bytes for the each entry
+            Assert.AreEqual(15, list.CalculateSize(FieldCodec.ForSFixed32(tag)));
+        }
+
+        [Test]
+        public void CalculateSize_VariableSizePacked()
+        {
+            var list = new RepeatedField<int> { 1, 500, 1};
+            var tag = WireFormat.MakeTag(1, WireFormat.WireType.LengthDelimited);
+            // 1 byte for the tag, 1 byte for the length,
+            // 1 byte for the first entry, 2 bytes for the second, 1 byte for the third
+            Assert.AreEqual(6, list.CalculateSize(FieldCodec.ForInt32(tag)));
+        }
+
+        [Test]
+        public void CalculateSize_FixedSizePacked()
+        {
+            var list = new RepeatedField<int> { 1, 500, 1 };
+            var tag = WireFormat.MakeTag(1, WireFormat.WireType.LengthDelimited);
+            // 1 byte for the tag, 1 byte for the length, 4 bytes per entry
+            Assert.AreEqual(14, list.CalculateSize(FieldCodec.ForSFixed32(tag)));
+        }
+
+        [Test]
+        public void TestNegativeEnumArray()
+        {
+            int arraySize = 1 + 1 + (11 * 5);
+            int msgSize = arraySize;
+            byte[] bytes = new byte[msgSize];
+            CodedOutputStream output = new CodedOutputStream(bytes);
+            uint tag = WireFormat.MakeTag(8, WireFormat.WireType.Varint);
+            for (int i = 0; i >= -5; i--)
+            {
+                output.WriteTag(tag);
+                output.WriteEnum(i);
+            }
+
+            Assert.AreEqual(0, output.SpaceLeft);
+
+            CodedInputStream input = new CodedInputStream(bytes);
+            tag = input.ReadTag();
+
+            RepeatedField<SampleEnum> values = new RepeatedField<SampleEnum>();
+            values.AddEntriesFrom(input, FieldCodec.ForEnum(tag, x => (int)x, x => (SampleEnum)x));
+
+            Assert.AreEqual(6, values.Count);
+            Assert.AreEqual(SampleEnum.None, values[0]);
+            Assert.AreEqual(((SampleEnum)(-1)), values[1]);
+            Assert.AreEqual(SampleEnum.NegativeValue, values[2]);
+            Assert.AreEqual(((SampleEnum)(-3)), values[3]);
+            Assert.AreEqual(((SampleEnum)(-4)), values[4]);
+            Assert.AreEqual(((SampleEnum)(-5)), values[5]);
+        }
+
+
+        [Test]
+        public void TestNegativeEnumPackedArray()
+        {
+            int arraySize = 1 + (10 * 5);
+            int msgSize = 1 + 1 + arraySize;
+            byte[] bytes = new byte[msgSize];
+            CodedOutputStream output = new CodedOutputStream(bytes);
+            // Length-delimited to show we want the packed representation
+            uint tag = WireFormat.MakeTag(8, WireFormat.WireType.LengthDelimited);
+            output.WriteTag(tag);
+            int size = 0;
+            for (int i = 0; i >= -5; i--)
+            {
+                size += CodedOutputStream.ComputeEnumSize(i);
+            }
+            output.WriteRawVarint32((uint)size);
+            for (int i = 0; i >= -5; i--)
+            {
+                output.WriteEnum(i);
+            }
+            Assert.AreEqual(0, output.SpaceLeft);
+
+            CodedInputStream input = new CodedInputStream(bytes);
+            tag = input.ReadTag();
+
+            RepeatedField<SampleEnum> values = new RepeatedField<SampleEnum>();
+            values.AddEntriesFrom(input, FieldCodec.ForEnum(tag, x => (int)x, x => (SampleEnum)x));
+
+            Assert.AreEqual(6, values.Count);
+            Assert.AreEqual(SampleEnum.None, values[0]);
+            Assert.AreEqual(((SampleEnum)(-1)), values[1]);
+            Assert.AreEqual(SampleEnum.NegativeValue, values[2]);
+            Assert.AreEqual(((SampleEnum)(-3)), values[3]);
+            Assert.AreEqual(((SampleEnum)(-4)), values[4]);
+            Assert.AreEqual(((SampleEnum)(-5)), values[5]);
+        }
+
+        [Test]
+        public void TestPackedRepeatedFieldCollectionNonDivisibleLength()
+        {
+            uint tag = WireFormat.MakeTag(10, WireFormat.WireType.LengthDelimited);
+            var codec = FieldCodec.ForFixed32(tag);
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            output.WriteTag(tag);
+            output.WriteString("A long string");
+            output.WriteTag(codec.Tag);
+            output.WriteRawVarint32((uint)codec.FixedSize - 1); // Length not divisible by FixedSize
+            output.WriteFixed32(uint.MaxValue);
+            output.Flush();
+            stream.Position = 0;
+
+            var input = new CodedInputStream(stream);
+            input.ReadTag();
+            input.ReadString();
+            input.ReadTag();
+            var field = new RepeatedField<uint>();
+            Assert.Throws<InvalidProtocolBufferException>(() => field.AddEntriesFrom(input, codec));
+
+            // Collection was not pre-initialized
+            Assert.AreEqual(0, field.Count);
+        }
+
+        [Test]
+        public void TestPackedRepeatedFieldCollectionNotAllocatedWhenLengthExceedsBuffer()
+        {
+            uint tag = WireFormat.MakeTag(10, WireFormat.WireType.LengthDelimited);
+            var codec = FieldCodec.ForFixed32(tag);
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            output.WriteTag(tag);
+            output.WriteString("A long string");
+            output.WriteTag(codec.Tag);
+            output.WriteRawVarint32((uint)codec.FixedSize);
+            // Note that there is no content for the packed field.
+            // The field length exceeds the remaining length of content.
+            output.Flush();
+            stream.Position = 0;
+
+            var input = new CodedInputStream(stream);
+            input.ReadTag();
+            input.ReadString();
+            input.ReadTag();
+            var field = new RepeatedField<uint>();
+            Assert.Throws<InvalidProtocolBufferException>(() => field.AddEntriesFrom(input, codec));
+
+            // Collection was not pre-initialized
+            Assert.AreEqual(0, field.Count);
+        }
+
+        [Test]
+        public void TestPackedRepeatedFieldCollectionNotAllocatedWhenLengthExceedsRemainingData()
+        {
+            uint tag = WireFormat.MakeTag(10, WireFormat.WireType.LengthDelimited);
+            var codec = FieldCodec.ForFixed32(tag);
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            output.WriteTag(tag);
+            output.WriteString("A long string");
+            output.WriteTag(codec.Tag);
+            output.WriteRawVarint32((uint)codec.FixedSize);
+            // Note that there is no content for the packed field.
+            // The field length exceeds the remaining length of the buffer.
+            output.Flush();
+            stream.Position = 0;
+
+            var sequence = ReadOnlySequenceFactory.CreateWithContent(stream.ToArray());
+            ParseContext.Initialize(sequence, out ParseContext ctx);
+
+            ctx.ReadTag();
+            ctx.ReadString();
+            ctx.ReadTag();
+            var field = new RepeatedField<uint>();
+            try
+            {
+                field.AddEntriesFrom(ref ctx, codec);
+                Assert.Fail();
+            }
+            catch (InvalidProtocolBufferException)
+            {
+            }
+
+            // Collection was not pre-initialized
+            Assert.AreEqual(0, field.Count);
+        }
+
+        // Fairly perfunctory tests for the non-generic IList implementation
+        [Test]
+        public void IList_Indexer()
+        {
+            var field = new RepeatedField<string> { "first", "second" };
+            IList list = field;
+            Assert.AreEqual("first", list[0]);
+            list[1] = "changed";
+            Assert.AreEqual("changed", field[1]);
+        }
+
+        [Test]
+        public void IList_Contains()
+        {
+            IList list = new RepeatedField<string> { "first", "second" };
+            Assert.IsTrue(list.Contains("second"));
+            Assert.IsFalse(list.Contains("third"));
+            Assert.IsFalse(list.Contains(new object()));
+        }
+
+        [Test]
+        public void IList_Add()
+        {
+            IList list = new RepeatedField<string> { "first", "second" };
+            list.Add("third");
+            CollectionAssert.AreEqual(new[] { "first", "second", "third" }, list);
+        }
+
+        [Test]
+        public void IList_Remove()
+        {
+            IList list = new RepeatedField<string> { "first", "second" };
+            list.Remove("third"); // No-op, no exception
+            list.Remove(new object()); // No-op, no exception
+            list.Remove("first");
+            CollectionAssert.AreEqual(new[] { "second" }, list);
+        }
+
+        [Test]
+        public void IList_IsFixedSize()
+        {
+            var field = new RepeatedField<string> { "first", "second" };
+            IList list = field;
+            Assert.IsFalse(list.IsFixedSize);
+        }
+
+        [Test]
+        public void IList_IndexOf()
+        {
+            IList list = new RepeatedField<string> { "first", "second" };
+            Assert.AreEqual(1, list.IndexOf("second"));
+            Assert.AreEqual(-1, list.IndexOf("third"));
+            Assert.AreEqual(-1, list.IndexOf(new object()));
+        }
+
+        [Test]
+        public void IList_SyncRoot()
+        {
+            IList list = new RepeatedField<string> { "first", "second" };
+            Assert.AreSame(list, list.SyncRoot);
+        }
+
+        [Test]
+        public void IList_CopyTo()
+        {
+            IList list = new RepeatedField<string> { "first", "second" };
+            string[] stringArray = new string[4];
+            list.CopyTo(stringArray, 1);
+            CollectionAssert.AreEqual(new[] { null, "first",  "second", null }, stringArray);
+
+            object[] objectArray = new object[4];
+            list.CopyTo(objectArray, 1);
+            CollectionAssert.AreEqual(new[] { null, "first", "second", null }, objectArray);
+
+            Assert.Throws<ArrayTypeMismatchException>(() => list.CopyTo(new StringBuilder[4], 1));
+            Assert.Throws<ArrayTypeMismatchException>(() => list.CopyTo(new int[4], 1));
+        }
+
+        [Test]
+        public void IList_IsSynchronized()
+        {
+            IList list = new RepeatedField<string> { "first", "second" };
+            Assert.IsFalse(list.IsSynchronized);
+        }
+
+        [Test]
+        public void IList_Insert()
+        {
+            IList list = new RepeatedField<string> { "first", "second" };
+            list.Insert(1, "middle");
+            CollectionAssert.AreEqual(new[] { "first", "middle", "second" }, list);
+        }
+
+        [Test]
+        public void ToString_Integers()
+        {
+            var list = new RepeatedField<int> { 5, 10, 20 };
+            var text = list.ToString();
+            Assert.AreEqual("[ 5, 10, 20 ]", text);
+        }
+
+        [Test]
+        public void ToString_Strings()
+        {
+            var list = new RepeatedField<string> { "x", "y", "z" };
+            var text = list.ToString();
+            Assert.AreEqual("[ \"x\", \"y\", \"z\" ]", text);
+        }
+
+        [Test]
+        public void ToString_Messages()
+        {
+            var list = new RepeatedField<TestAllTypes> { new TestAllTypes { SingleDouble = 1.5 }, new TestAllTypes { SingleInt32 = 10 } };
+            var text = list.ToString();
+            Assert.AreEqual("[ { \"singleDouble\": 1.5 }, { \"singleInt32\": 10 } ]", text);
+        }
+
+        [Test]
+        public void ToString_Empty()
+        {
+            var list = new RepeatedField<TestAllTypes> { };
+            var text = list.ToString();
+            Assert.AreEqual("[ ]", text);
+        }
+
+        [Test]
+        public void ToString_InvalidElementType()
+        {
+            var list = new RepeatedField<decimal> { 15m };
+            Assert.Throws<ArgumentException>(() => list.ToString());
+        }
+
+        [Test]
+        public void ToString_Timestamp()
+        {
+            var list = new RepeatedField<Timestamp> { Timestamp.FromDateTime(new DateTime(2015, 10, 1, 12, 34, 56, DateTimeKind.Utc)) };
+            var text = list.ToString();
+            Assert.AreEqual("[ \"2015-10-01T12:34:56Z\" ]", text);
+        }
+
+        [Test]
+        public void ToString_Struct()
+        {
+            var message = new Struct { Fields = { { "foo", new Value { NumberValue = 20 } } } };
+            var list = new RepeatedField<Struct> { message };
+            var text = list.ToString();
+            Assert.AreEqual(text, "[ { \"foo\": 20 } ]", message.ToString());
+        }
+
+        [Test]
+        public void NaNValuesComparedBitwise()
+        {
+            var list1 = new RepeatedField<double> { SampleNaNs.Regular, SampleNaNs.SignallingFlipped };
+            var list2 = new RepeatedField<double> { SampleNaNs.Regular, SampleNaNs.PayloadFlipped };
+            var list3 = new RepeatedField<double> { SampleNaNs.Regular, SampleNaNs.SignallingFlipped };
+
+            // All SampleNaNs have the same hashcode under certain targets (e.g. netcoreapp3.1)
+            EqualityTester.AssertInequality(list1, list2, checkHashcode: false);
+            EqualityTester.AssertEquality(list1, list3);
+            Assert.True(list1.Contains(SampleNaNs.SignallingFlipped));
+            Assert.False(list2.Contains(SampleNaNs.SignallingFlipped));
+        }
+
+        [Test]
+        public void Capacity_Increase()
+        {
+            // Unfortunately this case tests implementation details of RepeatedField.  This is necessary
+
+            var list = new RepeatedField<int>() { 1, 2, 3 };
+
+            Assert.AreEqual(8, list.Capacity);
+            Assert.AreEqual(3, list.Count);
+
+            list.Capacity = 10; // Set capacity to a larger value to trigger growth
+            Assert.AreEqual(10, list.Capacity, "Capacity increased");
+            Assert.AreEqual(3, list.Count);
+
+            CollectionAssert.AreEqual(new int[] {1, 2, 3}, list.ToArray(), "We didn't lose our data in the resize");
+        }
+
+        [Test]
+        public void Capacity_Decrease()
+        {
+            var list = new RepeatedField<int>() { 1, 2, 3 };
+
+            Assert.AreEqual(8, list.Capacity);
+            Assert.DoesNotThrow(() => list.Capacity = 5, "Can decrease capacity if new capacity is greater than list.Count");
+            Assert.AreEqual(5, list.Capacity);
+
+            Assert.DoesNotThrow(() => list.Capacity = 3, "Can set capacity exactly to list.Count" );
+
+            Assert.Throws<ArgumentOutOfRangeException>(() => list.Capacity = 2, "Can't set the capacity smaller than list.Count" );
+
+            Assert.Throws<ArgumentOutOfRangeException>(() => list.Capacity = 0, "Can't set the capacity to zero" );
+
+            Assert.Throws<ArgumentOutOfRangeException>(() => list.Capacity = -1, "Can't set the capacity to negative" );
+        }
+
+        [Test]
+        public void Capacity_Zero()
+        {
+            var list = new RepeatedField<int>() { 1 };
+            list.RemoveAt(0);
+            Assert.AreEqual(0, list.Count);
+            Assert.AreEqual(8, list.Capacity);
+
+            Assert.DoesNotThrow(() => list.Capacity = 0, "Can set Capacity to 0");
+            Assert.AreEqual(0, list.Capacity);
+        }
+
+        [Test]
+        public void Clear_CapacityUnaffected()
+        {
+            var list = new RepeatedField<int> { 1 };
+            Assert.AreEqual(1, list.Count);
+            Assert.AreEqual(8, list.Capacity);
+
+            list.Clear();
+            Assert.AreEqual(0, list.Count);
+            Assert.AreEqual(8, list.Capacity);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/Compatibility/PropertyInfoExtensionsTest.cs

@@ -0,0 +1,98 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using NUnit.Framework;
+using System.Reflection;
+
+namespace Google.Protobuf.Compatibility
+{
+    public class PropertyInfoExtensionsTest
+    {
+        public string PublicReadWrite { get; set; }
+        private string PrivateReadWrite { get; set; }
+        public string PublicReadPrivateWrite { get; private set; }
+        public string PrivateReadPublicWrite { private get; set; }
+        public string PublicReadOnly { get { return null; } }
+        private string PrivateReadOnly { get { return null; } }
+        public string PublicWriteOnly { set { } }
+        private string PrivateWriteOnly { set {  } }
+
+        [Test]
+        [TestCase("PublicReadWrite")]
+        [TestCase("PublicReadPrivateWrite")]
+        [TestCase("PublicReadOnly")]
+        public void GetGetMethod_Success(string name)
+        {
+            var propertyInfo = typeof(PropertyInfoExtensionsTest)
+                .GetProperty(name, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
+            Assert.IsNotNull(PropertyInfoExtensions.GetGetMethod(propertyInfo));
+        }
+
+        [Test]
+        [TestCase("PrivateReadWrite")]
+        [TestCase("PrivateReadPublicWrite")]
+        [TestCase("PrivateReadOnly")]
+        [TestCase("PublicWriteOnly")]
+        [TestCase("PrivateWriteOnly")]
+        public void GetGetMethod_NoAccessibleGetter(string name)
+        {
+            var propertyInfo = typeof(PropertyInfoExtensionsTest)
+                .GetProperty(name, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
+            Assert.IsNull(PropertyInfoExtensions.GetGetMethod(propertyInfo));
+        }
+
+        [Test]
+        [TestCase("PublicReadWrite")]
+        [TestCase("PrivateReadPublicWrite")]
+        [TestCase("PublicWriteOnly")]
+        public void GetSetMethod_Success(string name)
+        {
+            var propertyInfo = typeof(PropertyInfoExtensionsTest)
+                .GetProperty(name, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
+            Assert.IsNotNull(PropertyInfoExtensions.GetSetMethod(propertyInfo));
+        }
+
+        [Test]
+        [TestCase("PublicReadPrivateWrite")]
+        [TestCase("PrivateReadWrite")]
+        [TestCase("PrivateReadOnly")]
+        [TestCase("PublicReadOnly")]
+        [TestCase("PrivateWriteOnly")]
+        public void GetSetMethod_NoAccessibleGetter(string name)
+        {
+            var propertyInfo = typeof(PropertyInfoExtensionsTest)
+                .GetProperty(name, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
+            Assert.IsNull(PropertyInfoExtensions.GetSetMethod(propertyInfo));
+        }
+    }
+
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/Compatibility/TypeExtensionsTest.cs

@@ -0,0 +1,116 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+
+namespace Google.Protobuf.Compatibility
+{
+    public class TypeExtensionsTest
+    {
+        public class DerivedList : List<string> { }
+        public string PublicProperty { get; set; }
+        private string PrivateProperty { get; set; }
+
+        public void PublicMethod()
+        {
+        }
+
+        private void PrivateMethod()
+        {
+        }
+
+        [Test]
+        [TestCase(typeof(object), typeof(string), true)]
+        [TestCase(typeof(object), typeof(int), true)]
+        [TestCase(typeof(string), typeof(string), true)]
+        [TestCase(typeof(string), typeof(object), false)]
+        [TestCase(typeof(string), typeof(int), false)]
+        [TestCase(typeof(int), typeof(int), true)]
+        [TestCase(typeof(ValueType), typeof(int), true)]
+        [TestCase(typeof(long), typeof(int), false)] //
+        public void IsAssignableFrom(Type target, Type argument, bool expected)
+        {
+            Assert.AreEqual(expected, TypeExtensions.IsAssignableFrom(target, argument));
+        }
+
+        [Test]
+        [TestCase(typeof(DerivedList), "Count")] // Go up the type hierarchy
+        [TestCase(typeof(List<string>), "Count")]
+        [TestCase(typeof(List<>), "Count")]
+        [TestCase(typeof(TypeExtensionsTest), "PublicProperty")]
+        public void GetProperty_Success(Type type, string name)
+        {
+            var property = TypeExtensions.GetProperty(type, name);
+            Assert.IsNotNull(property);
+            Assert.AreEqual(name, property.Name);
+        }
+
+        [Test]
+        [TestCase(typeof(TypeExtensionsTest), "PrivateProperty")]
+        [TestCase(typeof(TypeExtensionsTest), "Garbage")]
+        public void GetProperty_NoSuchProperty(Type type, string name)
+        {
+            var property = TypeExtensions.GetProperty(type, name);
+            Assert.IsNull(property);
+        }
+
+        [Test]
+        [TestCase(typeof(DerivedList), "RemoveAt")] // Go up the type hierarchy
+        [TestCase(typeof(List<>), "RemoveAt")]
+        [TestCase(typeof(TypeExtensionsTest), "PublicMethod")]
+        public void GetMethod_Success(Type type, string name)
+        {
+            var method = TypeExtensions.GetMethod(type, name);
+            Assert.IsNotNull(method);
+            Assert.AreEqual(name, method.Name);
+        }
+
+        [Test]
+        [TestCase(typeof(TypeExtensionsTest), "PrivateMethod")]
+        [TestCase(typeof(TypeExtensionsTest), "GarbageMethod")]
+        public void GetMethod_NoSuchMethod(Type type, string name)
+        {
+            var method = TypeExtensions.GetMethod(type, name);
+            Assert.IsNull(method);
+        }
+
+        [Test]
+        [TestCase(typeof(List<string>), "IndexOf")]
+        public void GetMethod_Ambiguous(Type type, string name)
+        {
+            Assert.Throws<AmbiguousMatchException>(() => TypeExtensions.GetMethod(type, name));
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/DeprecatedMemberTest.cs

@@ -0,0 +1,67 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+    
+using System;
+using System.Reflection;
+using Google.Protobuf.TestProtos;
+using NUnit.Framework;
+using UnitTest.Issues.TestProtos;
+
+#pragma warning disable CS0612 // Type or member is obsolete
+namespace Google.Protobuf
+{
+    public class DeprecatedMemberTest
+    {
+        private static void AssertIsDeprecated(MemberInfo member)
+        {
+            Assert.NotNull(member);
+            Assert.IsTrue(member.IsDefined(typeof(ObsoleteAttribute), false), "Member not obsolete: " + member);
+        }
+
+        [Test]
+        public void TestDepreatedPrimitiveValue() =>
+            AssertIsDeprecated(typeof(TestDeprecatedFields).GetProperty(nameof(TestDeprecatedFields.DeprecatedInt32)));
+
+        [Test]
+        public void TestDeprecatedMessage() =>
+            AssertIsDeprecated(typeof(DeprecatedChild));
+
+        [Test]
+        public void TestDeprecatedEnum() =>
+            AssertIsDeprecated(typeof(DeprecatedEnum));
+
+        [Test]
+        public void TestDeprecatedEnumValue() =>
+            AssertIsDeprecated(typeof(DeprecatedEnum).GetField(nameof(DeprecatedEnum.DeprecatedZero)));
+    }
+}
+#pragma warning restore CS0612 // Type or member is obsolete

libs/protobuf/csharp/src/Google.Protobuf.Test/EqualityTester.cs

@@ -0,0 +1,65 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using NUnit.Framework;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Helper methods when testing equality. NUnit's Assert.AreEqual and
+    /// Assert.AreNotEqual methods try to be clever with collections, which can
+    /// be annoying...
+    /// </summary>
+    internal static class EqualityTester
+    {
+        public static void AssertEquality<T>(T first, T second) where T : IEquatable<T>
+        {
+            Assert.IsTrue(first.Equals(second));
+            Assert.IsTrue(first.Equals((object) second));
+            Assert.AreEqual(first.GetHashCode(), second.GetHashCode());
+        }
+
+        public static void AssertInequality<T>(T first, T second, bool checkHashcode = true) where T : IEquatable<T>
+        {
+            Assert.IsFalse(first.Equals(second));
+            Assert.IsFalse(first.Equals((object) second));
+            // While this isn't a requirement, the chances of this test failing due to
+            // coincidence rather than a bug are very small.
+            // For such rare cases, an argument can be used to disable the check.
+            if (checkHashcode && first != null && second != null)
+            {
+                Assert.AreNotEqual(first.GetHashCode(), second.GetHashCode());
+            }
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/ExtensionSetTest.cs

@@ -0,0 +1,228 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.Collections;
+using Google.Protobuf.TestProtos.Proto2;
+using NUnit.Framework;
+
+using static Google.Protobuf.TestProtos.Proto2.UnittestExtensions;
+
+namespace Google.Protobuf
+{
+    public class ExtensionSetTest
+    {
+        [Test]
+        public void EmptyExtensionSet()
+        {
+            ExtensionSet<TestAllExtensions> extensions = new ExtensionSet<TestAllExtensions>();
+            Assert.AreEqual(0, extensions.CalculateSize());
+        }
+
+        [Test]
+        public void MergeExtensionSet()
+        {
+            ExtensionSet<TestAllExtensions> extensions = null;
+            ExtensionSet.Set(ref extensions, OptionalBoolExtension, true);
+
+            ExtensionSet<TestAllExtensions> other = null;
+
+            Assert.IsFalse(ExtensionSet.Has(ref other, OptionalBoolExtension));
+            ExtensionSet.MergeFrom(ref other, extensions);
+            Assert.IsTrue(ExtensionSet.Has(ref other, OptionalBoolExtension));
+        }
+
+        [Test]
+        public void TestMergeCodedInput()
+        {
+            var message = new TestAllExtensions();
+            message.SetExtension(OptionalBoolExtension, true);
+            var serialized = message.ToByteArray();
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestAllExtensions.Parser.WithExtensionRegistry(new ExtensionRegistry() { OptionalBoolExtension }),
+                serialized,
+                other =>
+                {
+                    Assert.AreEqual(message, other);
+                    Assert.AreEqual(message.CalculateSize(), other.CalculateSize());
+                });
+        }
+
+        [Test]
+        public void TestMergeMessage()
+        {
+            var message = new TestAllExtensions();
+            message.SetExtension(OptionalBoolExtension, true);
+
+            var other = new TestAllExtensions();
+
+            Assert.AreNotEqual(message, other);
+            Assert.AreNotEqual(message.CalculateSize(), other.CalculateSize());
+
+            other.MergeFrom(message);
+
+            Assert.AreEqual(message, other);
+            Assert.AreEqual(message.CalculateSize(), other.CalculateSize());
+        }
+
+        [Test]
+        public void TryMergeFieldFrom_CodedInputStream()
+        {
+            var message = new TestAllExtensions();
+            message.SetExtension(OptionalStringExtension, "abcd");
+
+            var input = new CodedInputStream(message.ToByteArray());
+            input.ExtensionRegistry = new ExtensionRegistry { OptionalStringExtension };
+            input.ReadTag(); // TryMergeFieldFrom expects that a tag was just read and will inspect the LastTag value
+
+            ExtensionSet<TestAllExtensions> extensionSet = null;
+            // test the legacy overload of TryMergeFieldFrom that takes a CodedInputStream
+            Assert.IsTrue(ExtensionSet.TryMergeFieldFrom(ref extensionSet, input));
+            Assert.AreEqual("abcd", ExtensionSet.Get(ref extensionSet, OptionalStringExtension));
+        }
+
+        [Test]
+        public void GetSingle()
+        {
+            var extensionValue = new TestAllTypes.Types.NestedMessage() { Bb = 42 };
+            var untypedExtension = new Extension<TestAllExtensions, object>(OptionalNestedMessageExtension.FieldNumber, codec: null);
+            var wrongTypedExtension = new Extension<TestAllExtensions, TestAllTypes>(OptionalNestedMessageExtension.FieldNumber, codec: null);
+
+            var message = new TestAllExtensions();
+
+            var value1 = message.GetExtension(untypedExtension);
+            Assert.IsNull(value1);
+
+            message.SetExtension(OptionalNestedMessageExtension, extensionValue);
+            var value2 = message.GetExtension(untypedExtension);
+            Assert.IsNotNull(value2);
+
+            var valueBytes = ((IMessage)value2).ToByteArray();
+            var parsedValue = TestProtos.Proto2.TestAllTypes.Types.NestedMessage.Parser.ParseFrom(valueBytes);
+            Assert.AreEqual(extensionValue, parsedValue);
+
+            var ex = Assert.Throws<InvalidOperationException>(() => message.GetExtension(wrongTypedExtension));
+
+            var expectedMessage = "The stored extension value has a type of 'Google.Protobuf.TestProtos.Proto2.TestAllTypes+Types+NestedMessage, Google.Protobuf.Test.TestProtos, Version=1.0.0.0, Culture=neutral, PublicKeyToken=a7d26565bac4d604'. " +
+                "This a different from the requested type of 'Google.Protobuf.TestProtos.Proto2.TestAllTypes, Google.Protobuf.Test.TestProtos, Version=1.0.0.0, Culture=neutral, PublicKeyToken=a7d26565bac4d604'.";
+            Assert.AreEqual(expectedMessage, ex.Message);
+        }
+
+        [Test]
+        public void GetRepeated()
+        {
+            var extensionValue = new TestAllTypes.Types.NestedMessage() { Bb = 42 };
+            var untypedExtension = new Extension<TestAllExtensions, IList>(RepeatedNestedMessageExtension.FieldNumber, codec: null);
+            var wrongTypedExtension = new RepeatedExtension<TestAllExtensions, TestAllTypes>(RepeatedNestedMessageExtension.FieldNumber, codec: null);
+
+            var message = new TestAllExtensions();
+
+            var value1 = message.GetExtension(untypedExtension);
+            Assert.IsNull(value1);
+
+            var repeatedField = message.GetOrInitializeExtension<TestAllTypes.Types.NestedMessage>(RepeatedNestedMessageExtension);
+            repeatedField.Add(extensionValue);
+
+            var value2 = message.GetExtension(untypedExtension);
+            Assert.IsNotNull(value2);
+            Assert.AreEqual(1, value2.Count);
+
+            var valueBytes = ((IMessage)value2[0]).ToByteArray();
+            var parsedValue = TestProtos.Proto2.TestAllTypes.Types.NestedMessage.Parser.ParseFrom(valueBytes);
+            Assert.AreEqual(extensionValue, parsedValue);
+
+            var ex = Assert.Throws<InvalidOperationException>(() => message.GetExtension(wrongTypedExtension));
+
+            var expectedMessage = "The stored extension value has a type of 'Google.Protobuf.TestProtos.Proto2.TestAllTypes+Types+NestedMessage, Google.Protobuf.Test.TestProtos, Version=1.0.0.0, Culture=neutral, PublicKeyToken=a7d26565bac4d604'. " +
+                "This a different from the requested type of 'Google.Protobuf.TestProtos.Proto2.TestAllTypes, Google.Protobuf.Test.TestProtos, Version=1.0.0.0, Culture=neutral, PublicKeyToken=a7d26565bac4d604'.";
+            Assert.AreEqual(expectedMessage, ex.Message);
+        }
+
+        [Test]
+        public void TestEquals()
+        {
+            var message = new TestAllExtensions();
+            message.SetExtension(OptionalBoolExtension, true);
+
+            var other = new TestAllExtensions();
+
+            Assert.AreNotEqual(message, other);
+            Assert.AreNotEqual(message.CalculateSize(), other.CalculateSize());
+
+            other.SetExtension(OptionalBoolExtension, true);
+
+            Assert.AreEqual(message, other);
+            Assert.AreEqual(message.CalculateSize(), other.CalculateSize());
+        }
+
+        [Test]
+        public void TestHashCode()
+        {
+            var message = new TestAllExtensions();
+            var hashCode = message.GetHashCode();
+
+            message.SetExtension(OptionalBoolExtension, true);
+
+            Assert.AreNotEqual(hashCode, message.GetHashCode());
+        }
+
+        [Test]
+        public void TestClone()
+        {
+            var message = new TestAllExtensions();
+            message.SetExtension(OptionalBoolExtension, true);
+
+            var other = message.Clone();
+
+            Assert.AreEqual(message, other);
+            Assert.AreEqual(message.CalculateSize(), other.CalculateSize());
+        }
+
+        [Test]
+        public void TestDefaultValueRoundTrip()
+        {
+            var message = new TestAllExtensions();
+            message.SetExtension(OptionalBoolExtension, false);
+            Assert.IsFalse(message.GetExtension(OptionalBoolExtension));
+            Assert.IsTrue(message.HasExtension(OptionalBoolExtension));
+
+            var bytes = message.ToByteArray();
+            var registry = new ExtensionRegistry { OptionalBoolExtension };
+            var parsed = TestAllExtensions.Parser.WithExtensionRegistry(registry).ParseFrom(bytes);
+            Assert.IsFalse(parsed.GetExtension(OptionalBoolExtension));
+            Assert.IsTrue(parsed.HasExtension(OptionalBoolExtension));
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/FieldCodecTest.cs

@@ -0,0 +1,217 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System.Collections.Generic;
+using System.IO;
+using System.Reflection;
+using Google.Protobuf.TestProtos;
+using NUnit.Framework;
+
+namespace Google.Protobuf
+{
+    public class FieldCodecTest
+    {
+#pragma warning disable 0414 // Used by tests via reflection - do not remove!
+        private static readonly List<ICodecTestData> Codecs = new List<ICodecTestData>
+        {
+            new FieldCodecTestData<bool>(FieldCodec.ForBool(100), true, "FixedBool"),
+            new FieldCodecTestData<string>(FieldCodec.ForString(100), "sample", "String"),
+            new FieldCodecTestData<ByteString>(FieldCodec.ForBytes(100), ByteString.CopyFrom(1, 2, 3), "Bytes"),
+            new FieldCodecTestData<int>(FieldCodec.ForInt32(100), -1000, "Int32"),
+            new FieldCodecTestData<int>(FieldCodec.ForSInt32(100), -1000, "SInt32"),
+            new FieldCodecTestData<int>(FieldCodec.ForSFixed32(100), -1000, "SFixed32"),
+            new FieldCodecTestData<uint>(FieldCodec.ForUInt32(100), 1234, "UInt32"),
+            new FieldCodecTestData<uint>(FieldCodec.ForFixed32(100), 1234, "Fixed32"),
+            new FieldCodecTestData<long>(FieldCodec.ForInt64(100), -1000, "Int64"),
+            new FieldCodecTestData<long>(FieldCodec.ForSInt64(100), -1000, "SInt64"),
+            new FieldCodecTestData<long>(FieldCodec.ForSFixed64(100), -1000, "SFixed64"),
+            new FieldCodecTestData<ulong>(FieldCodec.ForUInt64(100), 1234, "UInt64"),
+            new FieldCodecTestData<ulong>(FieldCodec.ForFixed64(100), 1234, "Fixed64"),
+            new FieldCodecTestData<float>(FieldCodec.ForFloat(100), 1234.5f, "FixedFloat"),
+            new FieldCodecTestData<double>(FieldCodec.ForDouble(100), 1234567890.5d, "FixedDouble"),
+            new FieldCodecTestData<ForeignEnum>(
+                FieldCodec.ForEnum(100, t => (int) t, t => (ForeignEnum) t), ForeignEnum.ForeignBaz, "Enum"),
+            new FieldCodecTestData<ForeignMessage>(
+                FieldCodec.ForMessage(100, ForeignMessage.Parser), new ForeignMessage { C = 10 }, "Message"),
+        };
+#pragma warning restore 0414
+
+        [Test, TestCaseSource("Codecs")]
+        public void RoundTripWithTag(ICodecTestData codec)
+        {
+            codec.TestRoundTripWithTag();
+        }
+
+        [Test, TestCaseSource("Codecs")]
+        public void RoundTripRaw(ICodecTestData codec)
+        {
+            codec.TestRoundTripRaw();
+        }
+
+        [Test, TestCaseSource("Codecs")]
+        public void CalculateSize(ICodecTestData codec)
+        {
+            codec.TestCalculateSizeWithTag();
+        }
+
+        [Test, TestCaseSource("Codecs")]
+        public void DefaultValue(ICodecTestData codec)
+        {
+            codec.TestDefaultValue();
+        }
+
+        [Test, TestCaseSource("Codecs")]
+        public void FixedSize(ICodecTestData codec)
+        {
+            codec.TestFixedSize();
+        }
+
+        // This is ugly, but it means we can have a non-generic interface.
+        // It feels like NUnit should support this better, but I don't know
+        // of any better ways right now.
+        public interface ICodecTestData
+        {
+            void TestRoundTripRaw();
+            void TestRoundTripWithTag();
+            void TestCalculateSizeWithTag();
+            void TestDefaultValue();
+            void TestFixedSize();
+        }
+
+        public class FieldCodecTestData<T> : ICodecTestData
+        {
+            private readonly FieldCodec<T> codec;
+            private readonly T sampleValue;
+            private readonly string name;
+
+            public FieldCodecTestData(FieldCodec<T> codec, T sampleValue, string name)
+            {
+                this.codec = codec;
+                this.sampleValue = sampleValue;
+                this.name = name;
+            }
+
+            public void TestRoundTripRaw()
+            {
+                var stream = new MemoryStream();
+                var codedOutput = new CodedOutputStream(stream);
+                WriteContext.Initialize(codedOutput, out WriteContext ctx);
+                try
+                {
+                    // only write the value using the codec
+                    codec.ValueWriter(ref ctx, sampleValue);
+                }
+                finally
+                {
+                    ctx.CopyStateTo(codedOutput);
+                }
+                
+                codedOutput.Flush();
+                stream.Position = 0;
+                var codedInput = new CodedInputStream(stream);
+                Assert.AreEqual(sampleValue, codec.Read(codedInput));
+                Assert.IsTrue(codedInput.IsAtEnd);
+            }
+
+            public void TestRoundTripWithTag()
+            {
+                var stream = new MemoryStream();
+                var codedOutput = new CodedOutputStream(stream);
+                codec.WriteTagAndValue(codedOutput, sampleValue);
+                codedOutput.Flush();
+                stream.Position = 0;
+                var codedInput = new CodedInputStream(stream);
+                codedInput.AssertNextTag(codec.Tag);
+                Assert.AreEqual(sampleValue, codec.Read(codedInput));
+                Assert.IsTrue(codedInput.IsAtEnd);
+            }
+
+            public void TestCalculateSizeWithTag()
+            {
+                var stream = new MemoryStream();
+                var codedOutput = new CodedOutputStream(stream);
+                codec.WriteTagAndValue(codedOutput, sampleValue);
+                codedOutput.Flush();
+                Assert.AreEqual(stream.Position, codec.CalculateSizeWithTag(sampleValue));
+            }
+
+            public void TestDefaultValue()
+            {
+                // WriteTagAndValue ignores default values
+                var stream = new MemoryStream();
+                CodedOutputStream codedOutput;
+                codedOutput = new CodedOutputStream(stream);
+                codec.WriteTagAndValue(codedOutput, codec.DefaultValue);
+                codedOutput.Flush();
+                Assert.AreEqual(0, stream.Position);
+                Assert.AreEqual(0, codec.CalculateSizeWithTag(codec.DefaultValue));
+                if (typeof(T).GetTypeInfo().IsValueType)
+                {
+                    Assert.AreEqual(default(T), codec.DefaultValue);
+                }
+
+                // The plain ValueWriter/ValueReader delegates don't.
+                if (codec.DefaultValue != null) // This part isn't appropriate for message types.
+                {
+                    codedOutput = new CodedOutputStream(stream);
+                    WriteContext.Initialize(codedOutput, out WriteContext ctx);
+                    try
+                    {
+                        // only write the value using the codec
+                        codec.ValueWriter(ref ctx, codec.DefaultValue);
+                    }
+                    finally
+                    {
+                        ctx.CopyStateTo(codedOutput);
+                    }
+                    
+                    codedOutput.Flush();
+                    Assert.AreNotEqual(0, stream.Position);
+                    Assert.AreEqual(stream.Position, codec.ValueSizeCalculator(codec.DefaultValue));
+                    stream.Position = 0;
+                    var codedInput = new CodedInputStream(stream);
+                    Assert.AreEqual(codec.DefaultValue, codec.Read(codedInput));
+                }
+            }
+
+            public void TestFixedSize()
+            {
+                Assert.AreEqual(name.Contains("Fixed"), codec.FixedSize != 0);
+            }
+
+            public override string ToString()
+            {
+                return name;
+            }
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/FieldMaskTreeTest.cs

@@ -0,0 +1,519 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using Google.Protobuf.Collections;
+using Google.Protobuf.TestProtos;
+using NUnit.Framework;
+using Google.Protobuf.WellKnownTypes;
+
+namespace Google.Protobuf
+{
+    public class FieldMaskTreeTest
+    {
+        [Test]
+        public void AddFieldPath()
+        {
+            FieldMaskTree tree = new FieldMaskTree();
+            RepeatedField<string> paths = tree.ToFieldMask().Paths;
+            Assert.AreEqual(0, paths.Count);
+
+            tree.AddFieldPath("");
+            paths = tree.ToFieldMask().Paths;
+            Assert.AreEqual(1, paths.Count);
+            Assert.Contains("", paths);
+
+            // New branch.
+            tree.AddFieldPath("foo");
+            paths = tree.ToFieldMask().Paths;
+            Assert.AreEqual(2, paths.Count);
+            Assert.Contains("foo", paths);
+
+            // Redundant path.
+            tree.AddFieldPath("foo");
+            paths = tree.ToFieldMask().Paths;
+            Assert.AreEqual(2, paths.Count);
+
+            // New branch.
+            tree.AddFieldPath("bar.baz");
+            paths = tree.ToFieldMask().Paths;
+            Assert.AreEqual(3, paths.Count);
+            Assert.Contains("bar.baz", paths);
+
+            // Redundant sub-path.
+            tree.AddFieldPath("foo.bar");
+            paths = tree.ToFieldMask().Paths;
+            Assert.AreEqual(3, paths.Count);
+
+            // New branch from a non-root node.
+            tree.AddFieldPath("bar.quz");
+            paths = tree.ToFieldMask().Paths;
+            Assert.AreEqual(4, paths.Count);
+            Assert.Contains("bar.quz", paths);
+
+            // A path that matches several existing sub-paths.
+            tree.AddFieldPath("bar");
+            paths = tree.ToFieldMask().Paths;
+            Assert.AreEqual(3, paths.Count);
+            Assert.Contains("foo", paths);
+            Assert.Contains("bar", paths);
+        }
+
+        [Test]
+        public void MergeFromFieldMask()
+        {
+            FieldMaskTree tree = new FieldMaskTree();
+            tree.MergeFromFieldMask(new FieldMask
+            {
+                Paths = {"foo", "bar.baz", "bar.quz"}
+            });
+            RepeatedField<string> paths = tree.ToFieldMask().Paths;
+            Assert.AreEqual(3, paths.Count);
+            Assert.Contains("foo", paths);
+            Assert.Contains("bar.baz", paths);
+            Assert.Contains("bar.quz", paths);
+
+            tree.MergeFromFieldMask(new FieldMask
+            {
+                Paths = {"foo.bar", "bar"}
+            });
+            paths = tree.ToFieldMask().Paths;
+            Assert.AreEqual(2, paths.Count);
+            Assert.Contains("foo", paths);
+            Assert.Contains("bar", paths);
+        }
+
+        [Test]
+        public void IntersectFieldPath()
+        {
+            FieldMaskTree tree = new FieldMaskTree();
+            FieldMaskTree result = new FieldMaskTree();
+            tree.MergeFromFieldMask(new FieldMask
+            {
+                Paths = {"foo", "bar.baz", "bar.quz"}
+            });
+
+            // Empty path.
+            tree.IntersectFieldPath("", result);
+            RepeatedField<string> paths = result.ToFieldMask().Paths;
+            Assert.AreEqual(0, paths.Count);
+
+            // Non-exist path.
+            tree.IntersectFieldPath("quz", result);
+            paths = result.ToFieldMask().Paths;
+            Assert.AreEqual(0, paths.Count);
+
+            // Sub-path of an existing leaf.
+            tree.IntersectFieldPath("foo.bar", result);
+            paths = result.ToFieldMask().Paths;
+            Assert.AreEqual(1, paths.Count);
+            Assert.Contains("foo.bar", paths);
+
+            // Match an existing leaf node.
+            tree.IntersectFieldPath("foo", result);
+            paths = result.ToFieldMask().Paths;
+            Assert.AreEqual(1, paths.Count);
+            Assert.Contains("foo", paths);
+
+            // Non-exist path.
+            tree.IntersectFieldPath("bar.foo", result);
+            paths = result.ToFieldMask().Paths;
+            Assert.AreEqual(1, paths.Count);
+            Assert.Contains("foo", paths);
+
+            // Match a non-leaf node.
+            tree.IntersectFieldPath("bar", result);
+            paths = result.ToFieldMask().Paths;
+            Assert.AreEqual(3, paths.Count);
+            Assert.Contains("foo", paths);
+            Assert.Contains("bar.baz", paths);
+            Assert.Contains("bar.quz", paths);
+        }
+
+        private void Merge(FieldMaskTree tree, IMessage source, IMessage destination, FieldMask.MergeOptions options, bool useDynamicMessage)
+        {
+            if (useDynamicMessage)
+            {
+                var newSource = source.Descriptor.Parser.CreateTemplate();
+                newSource.MergeFrom(source.ToByteString());
+
+                var newDestination = source.Descriptor.Parser.CreateTemplate();
+                newDestination.MergeFrom(destination.ToByteString());
+
+                tree.Merge(newSource, newDestination, options);
+
+                // Clear before merging:
+                foreach (var fieldDescriptor in destination.Descriptor.Fields.InFieldNumberOrder())
+                {
+                    fieldDescriptor.Accessor.Clear(destination);
+                }
+                destination.MergeFrom(newDestination.ToByteString());
+            }
+            else
+            {
+                tree.Merge(source, destination, options);
+            }
+        }
+
+        [Test]
+        [TestCase(true)]
+        [TestCase(false)]
+        public void Merge(bool useDynamicMessage)
+        {
+            TestAllTypes value = new TestAllTypes
+            {
+                SingleInt32 = 1234,
+                SingleNestedMessage = new TestAllTypes.Types.NestedMessage {Bb = 5678},
+                RepeatedInt32 = {4321},
+                RepeatedNestedMessage = {new TestAllTypes.Types.NestedMessage {Bb = 8765}}
+            };
+
+            NestedTestAllTypes source = new NestedTestAllTypes
+            {
+                Payload = value,
+                Child = new NestedTestAllTypes {Payload = value}
+            };
+            // Now we have a message source with the following structure:
+            //   [root] -+- payload -+- single_int32
+            //           |           +- single_nested_message
+            //           |           +- repeated_int32
+            //           |           +- repeated_nested_message
+            //           |
+            //           +- child --- payload -+- single_int32
+            //                                 +- single_nested_message
+            //                                 +- repeated_int32
+            //                                 +- repeated_nested_message
+
+            FieldMask.MergeOptions options = new FieldMask.MergeOptions();
+
+            // Test merging each individual field.
+            NestedTestAllTypes destination = new NestedTestAllTypes();
+            Merge(new FieldMaskTree().AddFieldPath("payload.single_int32"),
+                source, destination, options, useDynamicMessage);
+            NestedTestAllTypes expected = new NestedTestAllTypes
+            {
+                Payload = new TestAllTypes
+                {
+                    SingleInt32 = 1234
+                }
+            };
+            Assert.AreEqual(expected, destination);
+
+            destination = new NestedTestAllTypes();
+            Merge(new FieldMaskTree().AddFieldPath("payload.single_nested_message"),
+                source, destination, options, useDynamicMessage);
+            expected = new NestedTestAllTypes
+            {
+                Payload = new TestAllTypes
+                {
+                    SingleNestedMessage = new TestAllTypes.Types.NestedMessage {Bb = 5678}
+                }
+            };
+            Assert.AreEqual(expected, destination);
+
+            destination = new NestedTestAllTypes();
+            Merge(new FieldMaskTree().AddFieldPath("payload.repeated_int32"),
+                source, destination, options, useDynamicMessage);
+            expected = new NestedTestAllTypes
+            {
+                Payload = new TestAllTypes
+                {
+                    RepeatedInt32 = {4321}
+                }
+            };
+            Assert.AreEqual(expected, destination);
+
+            destination = new NestedTestAllTypes();
+            Merge(new FieldMaskTree().AddFieldPath("payload.repeated_nested_message"),
+                source, destination, options, useDynamicMessage);
+            expected = new NestedTestAllTypes
+            {
+                Payload = new TestAllTypes
+                {
+                    RepeatedNestedMessage = {new TestAllTypes.Types.NestedMessage {Bb = 8765}}
+                }
+            };
+            Assert.AreEqual(expected, destination);
+
+            destination = new NestedTestAllTypes();
+            Merge(
+                new FieldMaskTree().AddFieldPath("child.payload.single_int32"),
+                source,
+                destination,
+                options,
+                useDynamicMessage);
+            expected = new NestedTestAllTypes
+            {
+                Child = new NestedTestAllTypes
+                {
+                    Payload = new TestAllTypes
+                    {
+                        SingleInt32 = 1234
+                    }
+                }
+            };
+            Assert.AreEqual(expected, destination);
+
+            destination = new NestedTestAllTypes();
+            Merge(
+                new FieldMaskTree().AddFieldPath("child.payload.single_nested_message"),
+                source,
+                destination,
+                options,
+                useDynamicMessage);
+            expected = new NestedTestAllTypes
+            {
+                Child = new NestedTestAllTypes
+                {
+                    Payload = new TestAllTypes
+                    {
+                        SingleNestedMessage = new TestAllTypes.Types.NestedMessage {Bb = 5678}
+                    }
+                }
+            };
+            Assert.AreEqual(expected, destination);
+
+            destination = new NestedTestAllTypes();
+            Merge(new FieldMaskTree().AddFieldPath("child.payload.repeated_int32"),
+                source, destination, options, useDynamicMessage);
+            expected = new NestedTestAllTypes
+            {
+                Child = new NestedTestAllTypes
+                {
+                    Payload = new TestAllTypes
+                    {
+                        RepeatedInt32 = {4321}
+                    }
+                }
+            };
+            Assert.AreEqual(expected, destination);
+
+            destination = new NestedTestAllTypes();
+            Merge(new FieldMaskTree().AddFieldPath("child.payload.repeated_nested_message"),
+                source, destination, options, useDynamicMessage);
+            expected = new NestedTestAllTypes
+            {
+                Child = new NestedTestAllTypes
+                {
+                    Payload = new TestAllTypes
+                    {
+                        RepeatedNestedMessage = {new TestAllTypes.Types.NestedMessage {Bb = 8765}}
+                    }
+                }
+            };
+            Assert.AreEqual(expected, destination);
+
+            destination = new NestedTestAllTypes();
+            Merge(new FieldMaskTree().AddFieldPath("child").AddFieldPath("payload"),
+                source, destination, options, useDynamicMessage);
+            Assert.AreEqual(source, destination);
+
+            // Test repeated options.
+            destination = new NestedTestAllTypes
+            {
+                Payload = new TestAllTypes
+                {
+                    RepeatedInt32 = { 1000 }
+                }
+            };
+            Merge(new FieldMaskTree().AddFieldPath("payload.repeated_int32"),
+                    source, destination, options, useDynamicMessage);
+            // Default behavior is to append repeated fields.
+            Assert.AreEqual(2, destination.Payload.RepeatedInt32.Count);
+            Assert.AreEqual(1000, destination.Payload.RepeatedInt32[0]);
+            Assert.AreEqual(4321, destination.Payload.RepeatedInt32[1]);
+            // Change to replace repeated fields.
+            options.ReplaceRepeatedFields = true;
+            Merge(new FieldMaskTree().AddFieldPath("payload.repeated_int32"),
+                source, destination, options, useDynamicMessage);
+            Assert.AreEqual(1, destination.Payload.RepeatedInt32.Count);
+            Assert.AreEqual(4321, destination.Payload.RepeatedInt32[0]);
+
+            // Test message options.
+            destination = new NestedTestAllTypes
+            {
+                Payload = new TestAllTypes
+                {
+                    SingleInt32 = 1000,
+                    SingleUint32 = 2000
+                }
+            };
+            Merge(new FieldMaskTree().AddFieldPath("payload"),
+                    source, destination, options, useDynamicMessage);
+            // Default behavior is to merge message fields.
+            Assert.AreEqual(1234, destination.Payload.SingleInt32);
+            Assert.AreEqual(2000, destination.Payload.SingleUint32);
+
+            // Test merging unset message fields.
+            NestedTestAllTypes clearedSource = source.Clone();
+            clearedSource.Payload = null;
+            destination = new NestedTestAllTypes();
+            Merge(new FieldMaskTree().AddFieldPath("payload"),
+                clearedSource, destination, options, useDynamicMessage);
+            Assert.IsNull(destination.Payload);
+
+            // Skip a message field if they are unset in both source and target.
+            destination = new NestedTestAllTypes();
+            Merge(new FieldMaskTree().AddFieldPath("payload.single_int32"),
+                clearedSource, destination, options, useDynamicMessage);
+            Assert.IsNull(destination.Payload);
+
+            // Change to replace message fields.
+            options.ReplaceMessageFields = true;
+            destination = new NestedTestAllTypes
+            {
+                Payload = new TestAllTypes
+                {
+                    SingleInt32 = 1000,
+                    SingleUint32 = 2000
+                }
+            };
+            Merge(new FieldMaskTree().AddFieldPath("payload"),
+                    source, destination, options, useDynamicMessage);
+            Assert.AreEqual(1234, destination.Payload.SingleInt32);
+            Assert.AreEqual(0, destination.Payload.SingleUint32);
+
+            // Test merging unset message fields.
+            destination = new NestedTestAllTypes
+            {
+                Payload = new TestAllTypes
+                {
+                    SingleInt32 = 1000,
+                    SingleUint32 = 2000
+                }
+            };
+            Merge(new FieldMaskTree().AddFieldPath("payload"),
+                    clearedSource, destination, options, useDynamicMessage);
+            Assert.IsNull(destination.Payload);
+
+            // Test merging unset primitive fields.
+            destination = source.Clone();
+            destination.Payload.SingleInt32 = 0;
+            NestedTestAllTypes sourceWithPayloadInt32Unset = destination;
+            destination = source.Clone();
+            Merge(new FieldMaskTree().AddFieldPath("payload.single_int32"),
+                sourceWithPayloadInt32Unset, destination, options, useDynamicMessage);
+            Assert.AreEqual(0, destination.Payload.SingleInt32);
+
+            // Change to clear unset primitive fields.
+            options.ReplacePrimitiveFields = true;
+            destination = source.Clone();
+            Merge(new FieldMaskTree().AddFieldPath("payload.single_int32"),
+                sourceWithPayloadInt32Unset, destination, options, useDynamicMessage);
+            Assert.IsNotNull(destination.Payload);
+        }
+
+        [Test]
+        public void MergeWrapperFieldsWithNonNullFieldsInSource()
+        {
+            // Instantiate a destination with wrapper-based field types.
+            var destination = new TestWellKnownTypes()
+            {
+                StringField = "Hello",
+                Int32Field = 12,
+                Int64Field = 24,
+                BoolField = true,
+            };
+
+            // Set up a targeted update.
+            var source = new TestWellKnownTypes()
+            {
+                StringField = "Hi",
+                Int64Field = 240
+            };
+
+            Merge(new FieldMaskTree().AddFieldPath("string_field").AddFieldPath("int64_field"),
+                source,
+                destination,
+                new FieldMask.MergeOptions(),
+                false);
+
+            // Make sure the targeted fields changed.
+            Assert.AreEqual("Hi", destination.StringField);
+            Assert.AreEqual(240, destination.Int64Field);
+
+            // Prove that non-targeted fields stay intact...
+            Assert.AreEqual(12, destination.Int32Field);
+            Assert.IsTrue(destination.BoolField);
+
+            // ...including default values which were not explicitly set in the destination object.
+            Assert.IsNull(destination.FloatField);
+        }
+
+        [Test]
+        [TestCase(false, "Hello", 24)]
+        [TestCase(true, null, null)]
+        public void MergeWrapperFieldsWithNullFieldsInSource(
+            bool replaceMessageFields,
+            string expectedStringValue,
+            long? expectedInt64Value)
+        {
+            // Instantiate a destination with wrapper-based field types.
+            var destination = new TestWellKnownTypes()
+            {
+                StringField = "Hello",
+                Int32Field = 12,
+                Int64Field = 24,
+                BoolField = true,
+            };
+
+            // Set up a targeted update with null valued fields.
+            var source = new TestWellKnownTypes()
+            {
+                StringField = null,
+                Int64Field = null
+            };
+
+            Merge(new FieldMaskTree().AddFieldPath("string_field").AddFieldPath("int64_field"),
+                source,
+                destination,
+                new FieldMask.MergeOptions()
+                {
+                    ReplaceMessageFields = replaceMessageFields
+                },
+                false);
+
+            // Make sure the targeted fields changed according to our expectations, depending on the value of ReplaceMessageFields.
+            // When ReplaceMessageFields is false, the null values are not applied to the destination, because, although wrapped types
+            // are semantically primitives, FieldMaskTree.Merge still treats them as message types in order to maintain consistency with other Protobuf
+            // libraries such as Java and C++.
+            Assert.AreEqual(expectedStringValue, destination.StringField);
+            Assert.AreEqual(expectedInt64Value, destination.Int64Field);
+
+            // Prove that non-targeted fields stay intact...
+            Assert.AreEqual(12, destination.Int32Field);
+            Assert.IsTrue(destination.BoolField);
+
+            // ...including default values which were not explicitly set in the destination object.
+            Assert.IsNull(destination.FloatField);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/GeneratedMessageTest.Proto2.cs

@@ -0,0 +1,427 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using Google.Protobuf.TestProtos.Proto2;
+using Proto2 = Google.Protobuf.TestProtos.Proto2;
+using NUnit.Framework;
+
+using static Google.Protobuf.TestProtos.Proto2.UnittestExtensions;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Tests around the generated TestAllTypes message in unittest.proto
+    /// </summary>
+    public partial class GeneratedMessageTest
+    {
+        [Test]
+        public void DefaultProto2Values()
+        {
+            var message = new TestAllTypes();
+            Assert.AreEqual(false, message.OptionalBool);
+            Assert.AreEqual(ByteString.Empty, message.OptionalBytes);
+            Assert.AreEqual(0.0, message.OptionalDouble);
+            Assert.AreEqual(0, message.OptionalFixed32);
+            Assert.AreEqual(0L, message.OptionalFixed64);
+            Assert.AreEqual(0.0f, message.OptionalFloat);
+            Assert.AreEqual(ForeignEnum.ForeignFoo, message.OptionalForeignEnum);
+            Assert.IsNull(message.OptionalForeignMessage);
+            Assert.AreEqual(ImportEnum.ImportFoo, message.OptionalImportEnum);
+            Assert.IsNull(message.OptionalImportMessage);
+            Assert.AreEqual(0, message.OptionalInt32);
+            Assert.AreEqual(0L, message.OptionalInt64);
+            Assert.AreEqual(Proto2.TestAllTypes.Types.NestedEnum.Foo, message.OptionalNestedEnum);
+            Assert.IsNull(message.OptionalNestedMessage);
+            Assert.IsNull(message.OptionalPublicImportMessage);
+            Assert.AreEqual(0, message.OptionalSfixed32);
+            Assert.AreEqual(0L, message.OptionalSfixed64);
+            Assert.AreEqual(0, message.OptionalSint32);
+            Assert.AreEqual(0L, message.OptionalSint64);
+            Assert.AreEqual("", message.OptionalString);
+            Assert.AreEqual(0U, message.OptionalUint32);
+            Assert.AreEqual(0UL, message.OptionalUint64);
+
+            // Repeated fields
+            Assert.AreEqual(0, message.RepeatedBool.Count);
+            Assert.AreEqual(0, message.RepeatedBytes.Count);
+            Assert.AreEqual(0, message.RepeatedDouble.Count);
+            Assert.AreEqual(0, message.RepeatedFixed32.Count);
+            Assert.AreEqual(0, message.RepeatedFixed64.Count);
+            Assert.AreEqual(0, message.RepeatedFloat.Count);
+            Assert.AreEqual(0, message.RepeatedForeignEnum.Count);
+            Assert.AreEqual(0, message.RepeatedForeignMessage.Count);
+            Assert.AreEqual(0, message.RepeatedImportEnum.Count);
+            Assert.AreEqual(0, message.RepeatedImportMessage.Count);
+            Assert.AreEqual(0, message.RepeatedNestedEnum.Count);
+            Assert.AreEqual(0, message.RepeatedNestedMessage.Count);
+            Assert.AreEqual(0, message.RepeatedSfixed32.Count);
+            Assert.AreEqual(0, message.RepeatedSfixed64.Count);
+            Assert.AreEqual(0, message.RepeatedSint32.Count);
+            Assert.AreEqual(0, message.RepeatedSint64.Count);
+            Assert.AreEqual(0, message.RepeatedString.Count);
+            Assert.AreEqual(0, message.RepeatedUint32.Count);
+            Assert.AreEqual(0, message.RepeatedUint64.Count);
+
+            // Oneof fields
+            Assert.AreEqual(Proto2.TestAllTypes.OneofFieldOneofCase.None, message.OneofFieldCase);
+            Assert.AreEqual(0, message.OneofUint32);
+            Assert.AreEqual("", message.OneofString);
+            Assert.AreEqual(ByteString.Empty, message.OneofBytes);
+            Assert.IsNull(message.OneofNestedMessage);
+
+            Assert.AreEqual(true, message.DefaultBool);
+            Assert.AreEqual(ByteString.CopyFromUtf8("world"), message.DefaultBytes);
+            Assert.AreEqual("123", message.DefaultCord);
+            Assert.AreEqual(52e3, message.DefaultDouble);
+            Assert.AreEqual(47, message.DefaultFixed32);
+            Assert.AreEqual(48, message.DefaultFixed64);
+            Assert.AreEqual(51.5, message.DefaultFloat);
+            Assert.AreEqual(ForeignEnum.ForeignBar, message.DefaultForeignEnum);
+            Assert.AreEqual(ImportEnum.ImportBar, message.DefaultImportEnum);
+            Assert.AreEqual(41, message.DefaultInt32);
+            Assert.AreEqual(42, message.DefaultInt64);
+            Assert.AreEqual(Proto2.TestAllTypes.Types.NestedEnum.Bar, message.DefaultNestedEnum);
+            Assert.AreEqual(49, message.DefaultSfixed32);
+            Assert.AreEqual(-50, message.DefaultSfixed64);
+            Assert.AreEqual(-45, message.DefaultSint32);
+            Assert.AreEqual(46, message.DefaultSint64);
+            Assert.AreEqual("hello", message.DefaultString);
+            Assert.AreEqual("abc", message.DefaultStringPiece);
+            Assert.AreEqual(43, message.DefaultUint32);
+            Assert.AreEqual(44, message.DefaultUint64);
+
+            Assert.False(message.HasDefaultBool);
+            Assert.False(message.HasDefaultBytes);
+            Assert.False(message.HasDefaultCord);
+            Assert.False(message.HasDefaultDouble);
+            Assert.False(message.HasDefaultFixed32);
+            Assert.False(message.HasDefaultFixed64);
+            Assert.False(message.HasDefaultFloat);
+            Assert.False(message.HasDefaultForeignEnum);
+            Assert.False(message.HasDefaultImportEnum);
+            Assert.False(message.HasDefaultInt32);
+            Assert.False(message.HasDefaultInt64);
+            Assert.False(message.HasDefaultNestedEnum);
+            Assert.False(message.HasDefaultSfixed32);
+            Assert.False(message.HasDefaultSfixed64);
+            Assert.False(message.HasDefaultSint32);
+            Assert.False(message.HasDefaultSint64);
+            Assert.False(message.HasDefaultString);
+            Assert.False(message.HasDefaultStringPiece);
+            Assert.False(message.HasDefaultUint32);
+            Assert.False(message.HasDefaultUint64);
+        }
+
+        [Test]
+        public void DefaultExtensionValues()
+        {
+            var message = new TestAllExtensions();
+            Assert.AreEqual(false, message.GetExtension(OptionalBoolExtension));
+            Assert.AreEqual(ByteString.Empty, message.GetExtension(OptionalBytesExtension));
+            Assert.AreEqual(0.0, message.GetExtension(OptionalDoubleExtension));
+            Assert.AreEqual(0, message.GetExtension(OptionalFixed32Extension));
+            Assert.AreEqual(0L, message.GetExtension(OptionalFixed64Extension));
+            Assert.AreEqual(0.0f, message.GetExtension(OptionalFloatExtension));
+            Assert.AreEqual(ForeignEnum.ForeignFoo, message.GetExtension(OptionalForeignEnumExtension));
+            Assert.IsNull(message.GetExtension(OptionalForeignMessageExtension));
+            Assert.AreEqual(ImportEnum.ImportFoo, message.GetExtension(OptionalImportEnumExtension));
+            Assert.IsNull(message.GetExtension(OptionalImportMessageExtension));
+            Assert.AreEqual(0, message.GetExtension(OptionalInt32Extension));
+            Assert.AreEqual(0L, message.GetExtension(OptionalInt64Extension));
+            Assert.AreEqual(Proto2.TestAllTypes.Types.NestedEnum.Foo, message.GetExtension(OptionalNestedEnumExtension));
+            Assert.IsNull(message.GetExtension(OptionalNestedMessageExtension));
+            Assert.IsNull(message.GetExtension(OptionalPublicImportMessageExtension));
+            Assert.AreEqual(0, message.GetExtension(OptionalSfixed32Extension));
+            Assert.AreEqual(0L, message.GetExtension(OptionalSfixed64Extension));
+            Assert.AreEqual(0, message.GetExtension(OptionalSint32Extension));
+            Assert.AreEqual(0L, message.GetExtension(OptionalSint64Extension));
+            Assert.AreEqual("", message.GetExtension(OptionalStringExtension));
+            Assert.AreEqual(0U, message.GetExtension(OptionalUint32Extension));
+            Assert.AreEqual(0UL, message.GetExtension(OptionalUint64Extension));
+
+            // Repeated fields
+            Assert.IsNull(message.GetExtension(RepeatedBoolExtension));
+            Assert.IsNull(message.GetExtension(RepeatedBytesExtension));
+            Assert.IsNull(message.GetExtension(RepeatedDoubleExtension));
+            Assert.IsNull(message.GetExtension(RepeatedFixed32Extension));
+            Assert.IsNull(message.GetExtension(RepeatedFixed64Extension));
+            Assert.IsNull(message.GetExtension(RepeatedFloatExtension));
+            Assert.IsNull(message.GetExtension(RepeatedForeignEnumExtension));
+            Assert.IsNull(message.GetExtension(RepeatedForeignMessageExtension));
+            Assert.IsNull(message.GetExtension(RepeatedImportEnumExtension));
+            Assert.IsNull(message.GetExtension(RepeatedImportMessageExtension));
+            Assert.IsNull(message.GetExtension(RepeatedNestedEnumExtension));
+            Assert.IsNull(message.GetExtension(RepeatedNestedMessageExtension));
+            Assert.IsNull(message.GetExtension(RepeatedSfixed32Extension));
+            Assert.IsNull(message.GetExtension(RepeatedSfixed64Extension));
+            Assert.IsNull(message.GetExtension(RepeatedSint32Extension));
+            Assert.IsNull(message.GetExtension(RepeatedSint64Extension));
+            Assert.IsNull(message.GetExtension(RepeatedStringExtension));
+            Assert.IsNull(message.GetExtension(RepeatedUint32Extension));
+            Assert.IsNull(message.GetExtension(RepeatedUint64Extension));
+
+            // Oneof fields
+            Assert.AreEqual(0, message.GetExtension(OneofUint32Extension));
+            Assert.AreEqual("", message.GetExtension(OneofStringExtension));
+            Assert.AreEqual(ByteString.Empty, message.GetExtension(OneofBytesExtension));
+            Assert.IsNull(message.GetExtension(OneofNestedMessageExtension));
+
+            Assert.AreEqual(true, message.GetExtension(DefaultBoolExtension));
+            Assert.AreEqual(ByteString.CopyFromUtf8("world"), message.GetExtension(DefaultBytesExtension));
+            Assert.AreEqual("123", message.GetExtension(DefaultCordExtension));
+            Assert.AreEqual(52e3, message.GetExtension(DefaultDoubleExtension));
+            Assert.AreEqual(47, message.GetExtension(DefaultFixed32Extension));
+            Assert.AreEqual(48, message.GetExtension(DefaultFixed64Extension));
+            Assert.AreEqual(51.5, message.GetExtension(DefaultFloatExtension));
+            Assert.AreEqual(ForeignEnum.ForeignBar, message.GetExtension(DefaultForeignEnumExtension));
+            Assert.AreEqual(ImportEnum.ImportBar, message.GetExtension(DefaultImportEnumExtension));
+            Assert.AreEqual(41, message.GetExtension(DefaultInt32Extension));
+            Assert.AreEqual(42, message.GetExtension(DefaultInt64Extension));
+            Assert.AreEqual(Proto2.TestAllTypes.Types.NestedEnum.Bar, message.GetExtension(DefaultNestedEnumExtension));
+            Assert.AreEqual(49, message.GetExtension(DefaultSfixed32Extension));
+            Assert.AreEqual(-50, message.GetExtension(DefaultSfixed64Extension));
+            Assert.AreEqual(-45, message.GetExtension(DefaultSint32Extension));
+            Assert.AreEqual(46, message.GetExtension(DefaultSint64Extension));
+            Assert.AreEqual("hello", message.GetExtension(DefaultStringExtension));
+            Assert.AreEqual("abc", message.GetExtension(DefaultStringPieceExtension));
+            Assert.AreEqual(43, message.GetExtension(DefaultUint32Extension));
+            Assert.AreEqual(44, message.GetExtension(DefaultUint64Extension));
+
+            Assert.False(message.HasExtension(DefaultBoolExtension));
+            Assert.False(message.HasExtension(DefaultBytesExtension));
+            Assert.False(message.HasExtension(DefaultCordExtension));
+            Assert.False(message.HasExtension(DefaultDoubleExtension));
+            Assert.False(message.HasExtension(DefaultFixed32Extension));
+            Assert.False(message.HasExtension(DefaultFixed64Extension));
+            Assert.False(message.HasExtension(DefaultFloatExtension));
+            Assert.False(message.HasExtension(DefaultForeignEnumExtension));
+            Assert.False(message.HasExtension(DefaultImportEnumExtension));
+            Assert.False(message.HasExtension(DefaultInt32Extension));
+            Assert.False(message.HasExtension(DefaultInt64Extension));
+            Assert.False(message.HasExtension(DefaultNestedEnumExtension));
+            Assert.False(message.HasExtension(DefaultSfixed32Extension));
+            Assert.False(message.HasExtension(DefaultSfixed64Extension));
+            Assert.False(message.HasExtension(DefaultSint32Extension));
+            Assert.False(message.HasExtension(DefaultSint64Extension));
+            Assert.False(message.HasExtension(DefaultStringExtension));
+            Assert.False(message.HasExtension(DefaultStringPieceExtension));
+            Assert.False(message.HasExtension(DefaultUint32Extension));
+            Assert.False(message.HasExtension(DefaultUint64Extension));
+        }
+
+        [Test]
+        public void FieldPresence()
+        {
+            var message = new TestAllTypes();
+
+            Assert.False(message.HasOptionalBool);
+            Assert.False(message.OptionalBool);
+
+            message.OptionalBool = true;
+
+            Assert.True(message.HasOptionalBool);
+            Assert.True(message.OptionalBool);
+
+            message.OptionalBool = false;
+
+            Assert.True(message.HasOptionalBool);
+            Assert.False(message.OptionalBool);
+
+            message.ClearOptionalBool();
+
+            Assert.False(message.HasOptionalBool);
+            Assert.False(message.OptionalBool);
+
+            Assert.False(message.HasDefaultBool);
+            Assert.True(message.DefaultBool);
+
+            message.DefaultBool = false;
+
+            Assert.True(message.HasDefaultBool);
+            Assert.False(message.DefaultBool);
+
+            message.DefaultBool = true;
+
+            Assert.True(message.HasDefaultBool);
+            Assert.True(message.DefaultBool);
+
+            message.ClearDefaultBool();
+
+            Assert.False(message.HasDefaultBool);
+            Assert.True(message.DefaultBool);
+        }
+
+        [Test]
+        public void RequiredFields()
+        {
+            var message = new TestRequired();
+            Assert.False(message.IsInitialized());
+
+            message.A = 1;
+            message.B = 2;
+            message.C = 3;
+
+            Assert.True(message.IsInitialized());
+        }
+
+        /// <summary>
+        /// Code was accidentally left in message parser that threw exceptions when missing required fields after parsing.
+        /// We've decided to not throw exceptions on missing fields, instead leaving it up to the consumer how they
+        /// want to check and handle missing fields.
+        /// </summary>
+        [Test]
+        public void RequiredFieldsNoThrow()
+        {
+            Assert.DoesNotThrow(() => MessageParsingHelpers.AssertReadingMessage(TestRequired.Parser, new byte[0], m => { }));
+            Assert.DoesNotThrow(() => MessageParsingHelpers.AssertReadingMessage(TestRequired.Parser as MessageParser, new byte[0], m => { }));
+        }
+
+        [Test]
+        public void RequiredFieldsInExtensions()
+        {
+            var message = new TestAllExtensions();
+            Assert.True(message.IsInitialized());
+
+            message.SetExtension(TestRequired.Extensions.Single, new TestRequired());
+
+            Assert.False(message.IsInitialized());
+
+            var extensionMessage = message.GetExtension(TestRequired.Extensions.Single);
+            extensionMessage.A = 1;
+            extensionMessage.B = 2;
+            extensionMessage.C = 3;
+
+            Assert.True(message.IsInitialized());
+
+            message.GetOrInitializeExtension(TestRequired.Extensions.Multi);
+
+            Assert.True(message.IsInitialized());
+
+            message.GetExtension(TestRequired.Extensions.Multi).Add(new TestRequired());
+
+            Assert.False(message.IsInitialized());
+
+            extensionMessage = message.GetExtension(TestRequired.Extensions.Multi)[0];
+            extensionMessage.A = 1;
+            extensionMessage.B = 2;
+            extensionMessage.C = 3;
+
+            Assert.True(message.IsInitialized());
+
+            message.SetExtension(UnittestExtensions.OptionalBoolExtension, true);
+
+            Assert.True(message.IsInitialized());
+
+            message.GetOrInitializeExtension(UnittestExtensions.RepeatedBoolExtension).Add(true);
+
+            Assert.True(message.IsInitialized());
+        }
+
+        [Test]
+        public void RequiredFieldInNestedMessageMapValue()
+        {
+            var message = new TestRequiredMap();
+            message.Foo.Add(0, new TestRequiredMap.Types.NestedMessage());
+
+            Assert.False(message.IsInitialized());
+
+            message.Foo[0].RequiredInt32 = 12;
+
+            Assert.True(message.IsInitialized());
+        }
+
+        [Test]
+        public void RoundTrip_Groups()
+        {
+            var message = new TestAllTypes
+            {
+                OptionalGroup = new TestAllTypes.Types.OptionalGroup
+                {
+                    A = 10
+                },
+                RepeatedGroup =
+                {
+                    new TestAllTypes.Types.RepeatedGroup { A = 10 },
+                    new TestAllTypes.Types.RepeatedGroup { A = 20 },
+                    new TestAllTypes.Types.RepeatedGroup { A = 30 }
+                }
+            };
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertRoundtrip(Proto2.TestAllTypes.Parser, message);
+        }
+
+        [Test]
+        public void RoundTrip_ExtensionGroups()
+        {
+            var message = new TestAllExtensions();
+            message.SetExtension(UnittestExtensions.OptionalGroupExtension, new OptionalGroup_extension { A = 10 });
+            message.GetOrInitializeExtension(UnittestExtensions.RepeatedGroupExtension).AddRange(new[]
+            {
+                new RepeatedGroup_extension { A = 10 },
+                new RepeatedGroup_extension { A = 20 },
+                new RepeatedGroup_extension { A = 30 }
+            });
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertRoundtrip(
+                TestAllExtensions.Parser.WithExtensionRegistry(new ExtensionRegistry() { UnittestExtensions.OptionalGroupExtension, UnittestExtensions.RepeatedGroupExtension }),
+                message);
+        }
+
+        [Test]
+        public void RoundTrip_NestedExtensionGroup()
+        {
+            var message = new TestGroupExtension();
+            message.SetExtension(TestNestedExtension.Extensions.OptionalGroupExtension, new TestNestedExtension.Types.OptionalGroup_extension { A = 10 });
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+            
+            MessageParsingHelpers.AssertRoundtrip(
+                TestGroupExtension.Parser.WithExtensionRegistry(new ExtensionRegistry() { TestNestedExtension.Extensions.OptionalGroupExtension }),
+                message);
+        }
+
+        [Test]
+        public void RoundTrip_ParseUsingCodedInput()
+        {
+            var message = new TestAllExtensions();
+            message.SetExtension(UnittestExtensions.OptionalBoolExtension, true);
+            byte[] bytes = message.ToByteArray();
+            using CodedInputStream input = new CodedInputStream(bytes);
+            var parsed = TestAllExtensions.Parser.WithExtensionRegistry(new ExtensionRegistry() { UnittestExtensions.OptionalBoolExtension }).ParseFrom(input);
+            Assert.AreEqual(message, parsed);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/GeneratedMessageTest.cs

@@ -0,0 +1,839 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.IO;
+using Google.Protobuf.TestProtos;
+using NUnit.Framework;
+using System.Linq;
+using Google.Protobuf.WellKnownTypes;
+using Google.Protobuf.Collections;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Tests around the generated TestAllTypes message.
+    /// </summary>
+    public partial class GeneratedMessageTest
+    {
+        [Test]
+        public void EmptyMessageFieldDistinctFromMissingMessageField()
+        {
+            // This demonstrates what we're really interested in...
+            var message1 = new TestAllTypes { SingleForeignMessage = new ForeignMessage() };
+            var message2 = new TestAllTypes(); // SingleForeignMessage is null
+            EqualityTester.AssertInequality(message1, message2);
+        }
+
+        [Test]
+        public void DefaultValues()
+        {
+            // Single fields
+            var message = new TestAllTypes();
+            Assert.AreEqual(false, message.SingleBool);
+            Assert.AreEqual(ByteString.Empty, message.SingleBytes);
+            Assert.AreEqual(0.0, message.SingleDouble);
+            Assert.AreEqual(0, message.SingleFixed32);
+            Assert.AreEqual(0L, message.SingleFixed64);
+            Assert.AreEqual(0.0f, message.SingleFloat);
+            Assert.AreEqual(ForeignEnum.ForeignUnspecified, message.SingleForeignEnum);
+            Assert.IsNull(message.SingleForeignMessage);
+            Assert.AreEqual(ImportEnum.Unspecified, message.SingleImportEnum);
+            Assert.IsNull(message.SingleImportMessage);
+            Assert.AreEqual(0, message.SingleInt32);
+            Assert.AreEqual(0L, message.SingleInt64);
+            Assert.AreEqual(TestAllTypes.Types.NestedEnum.Unspecified, message.SingleNestedEnum);
+            Assert.IsNull(message.SingleNestedMessage);
+            Assert.IsNull(message.SinglePublicImportMessage);
+            Assert.AreEqual(0, message.SingleSfixed32);
+            Assert.AreEqual(0L, message.SingleSfixed64);
+            Assert.AreEqual(0, message.SingleSint32);
+            Assert.AreEqual(0L, message.SingleSint64);
+            Assert.AreEqual("", message.SingleString);
+            Assert.AreEqual(0U, message.SingleUint32);
+            Assert.AreEqual(0UL, message.SingleUint64);
+
+            // Repeated fields
+            Assert.AreEqual(0, message.RepeatedBool.Count);
+            Assert.AreEqual(0, message.RepeatedBytes.Count);
+            Assert.AreEqual(0, message.RepeatedDouble.Count);
+            Assert.AreEqual(0, message.RepeatedFixed32.Count);
+            Assert.AreEqual(0, message.RepeatedFixed64.Count);
+            Assert.AreEqual(0, message.RepeatedFloat.Count);
+            Assert.AreEqual(0, message.RepeatedForeignEnum.Count);
+            Assert.AreEqual(0, message.RepeatedForeignMessage.Count);
+            Assert.AreEqual(0, message.RepeatedImportEnum.Count);
+            Assert.AreEqual(0, message.RepeatedImportMessage.Count);
+            Assert.AreEqual(0, message.RepeatedNestedEnum.Count);
+            Assert.AreEqual(0, message.RepeatedNestedMessage.Count);
+            Assert.AreEqual(0, message.RepeatedPublicImportMessage.Count);
+            Assert.AreEqual(0, message.RepeatedSfixed32.Count);
+            Assert.AreEqual(0, message.RepeatedSfixed64.Count);
+            Assert.AreEqual(0, message.RepeatedSint32.Count);
+            Assert.AreEqual(0, message.RepeatedSint64.Count);
+            Assert.AreEqual(0, message.RepeatedString.Count);
+            Assert.AreEqual(0, message.RepeatedUint32.Count);
+            Assert.AreEqual(0, message.RepeatedUint64.Count);
+
+            // Oneof fields
+            Assert.AreEqual(TestAllTypes.OneofFieldOneofCase.None, message.OneofFieldCase);
+            Assert.AreEqual(0, message.OneofUint32);
+            Assert.AreEqual("", message.OneofString);
+            Assert.AreEqual(ByteString.Empty, message.OneofBytes);
+            Assert.IsNull(message.OneofNestedMessage);
+        }
+
+        [Test]
+        public void NullStringAndBytesRejected()
+        {
+            var message = new TestAllTypes();
+            Assert.Throws<ArgumentNullException>(() => message.SingleString = null);
+            Assert.Throws<ArgumentNullException>(() => message.OneofString = null);
+            Assert.Throws<ArgumentNullException>(() => message.SingleBytes = null);
+            Assert.Throws<ArgumentNullException>(() => message.OneofBytes = null);
+        }
+
+        [Test]
+        public void RoundTrip_Empty()
+        {
+            var message = new TestAllTypes();
+            // Without setting any values, there's nothing to write.
+            byte[] bytes = message.ToByteArray();
+            Assert.AreEqual(0, bytes.Length);
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertRoundtrip(TestAllTypes.Parser, message);
+        }
+
+        [Test]
+        public void RoundTrip_SingleValues()
+        {
+            var message = new TestAllTypes
+            {
+                SingleBool = true,
+                SingleBytes = ByteString.CopyFrom(1, 2, 3, 4),
+                SingleDouble = 23.5,
+                SingleFixed32 = 23,
+                SingleFixed64 = 1234567890123,
+                SingleFloat = 12.25f,
+                SingleForeignEnum = ForeignEnum.ForeignBar,
+                SingleForeignMessage = new ForeignMessage { C = 10 },
+                SingleImportEnum = ImportEnum.ImportBaz,
+                SingleImportMessage = new ImportMessage { D = 20 },
+                SingleInt32 = 100,
+                SingleInt64 = 3210987654321,
+                SingleNestedEnum = TestAllTypes.Types.NestedEnum.Foo,
+                SingleNestedMessage = new TestAllTypes.Types.NestedMessage { Bb = 35 },
+                SinglePublicImportMessage = new PublicImportMessage { E = 54 },
+                SingleSfixed32 = -123,
+                SingleSfixed64 = -12345678901234,
+                SingleSint32 = -456,
+                SingleSint64 = -12345678901235,
+                SingleString = "test",
+                SingleUint32 = uint.MaxValue,
+                SingleUint64 = ulong.MaxValue
+            };
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertRoundtrip(TestAllTypes.Parser, message);
+        }
+
+        [Test]
+        public void RoundTrip_RepeatedValues()
+        {
+            var message = new TestAllTypes
+            {
+                RepeatedBool = { true, false },
+                RepeatedBytes = { ByteString.CopyFrom(1, 2, 3, 4), ByteString.CopyFrom(5, 6) },
+                RepeatedDouble = { -12.25, 23.5 },
+                RepeatedFixed32 = { uint.MaxValue, 23 },
+                RepeatedFixed64 = { ulong.MaxValue, 1234567890123 },
+                RepeatedFloat = { 100f, 12.25f },
+                RepeatedForeignEnum = { ForeignEnum.ForeignFoo, ForeignEnum.ForeignBar },
+                RepeatedForeignMessage = { new ForeignMessage(), new ForeignMessage { C = 10 } },
+                RepeatedImportEnum = { ImportEnum.ImportBaz, ImportEnum.Unspecified },
+                RepeatedImportMessage = { new ImportMessage { D = 20 }, new ImportMessage { D = 25 } },
+                RepeatedInt32 = { 100, 200 },
+                RepeatedInt64 = { 3210987654321, long.MaxValue },
+                RepeatedNestedEnum = { TestAllTypes.Types.NestedEnum.Foo, TestAllTypes.Types.NestedEnum.Neg },
+                RepeatedNestedMessage = { new TestAllTypes.Types.NestedMessage { Bb = 35 }, new TestAllTypes.Types.NestedMessage { Bb = 10 } },
+                RepeatedPublicImportMessage = { new PublicImportMessage { E = 54 }, new PublicImportMessage { E = -1 } },
+                RepeatedSfixed32 = { -123, 123 },
+                RepeatedSfixed64 = { -12345678901234, 12345678901234 },
+                RepeatedSint32 = { -456, 100 },
+                RepeatedSint64 = { -12345678901235, 123 },
+                RepeatedString = { "foo", "bar" },
+                RepeatedUint32 = { uint.MaxValue, uint.MinValue },
+                RepeatedUint64 = { ulong.MaxValue, uint.MinValue }
+            };
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertRoundtrip(TestAllTypes.Parser, message);
+        }
+
+        // Note that not every map within map_unittest_proto3 is used. They all go through very
+        // similar code paths. The fact that all maps are present is validation that we have codecs
+        // for every type.
+        [Test]
+        public void RoundTrip_Maps()
+        {
+            var message = new TestMap
+            {
+                MapBoolBool = {
+                    { false, true },
+                    { true, false }
+                },
+                MapInt32Bytes = {
+                    { 5, ByteString.CopyFrom(6, 7, 8) },
+                    { 25, ByteString.CopyFrom(1, 2, 3, 4, 5) },
+                    { 10, ByteString.Empty }
+                },
+                MapInt32ForeignMessage = {
+                    { 0, new ForeignMessage { C = 10 } },
+                    { 5, new ForeignMessage() },
+                },
+                MapInt32Enum = {
+                    { 1, MapEnum.Bar },
+                    { 2000, MapEnum.Foo }
+                }
+            };
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertRoundtrip(TestMap.Parser, message);
+        }
+
+        [Test]
+        public void MapWithEmptyEntry()
+        {
+            var message = new TestMap
+            {
+                MapInt32Bytes = { { 0, ByteString.Empty } }
+            };
+
+            byte[] bytes = message.ToByteArray();
+            Assert.AreEqual(2, bytes.Length); // Tag for field entry (1 byte), length of entry (0; 1 byte)
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestMap.Parser,
+                bytes,
+                parsed=>
+                {
+                    Assert.AreEqual(1, parsed.MapInt32Bytes.Count);
+                    Assert.AreEqual(ByteString.Empty, parsed.MapInt32Bytes[0]);
+                });
+        }
+
+        [Test]
+        public void MapWithOnlyValue()
+        {
+            // Hand-craft the stream to contain a single entry with just a value.
+            var memoryStream = new MemoryStream();
+            var output = new CodedOutputStream(memoryStream);
+            output.WriteTag(TestMap.MapInt32ForeignMessageFieldNumber, WireFormat.WireType.LengthDelimited);
+            var nestedMessage = new ForeignMessage { C = 20 };
+            // Size of the entry (tag, size written by WriteMessage, data written by WriteMessage)
+            output.WriteLength(2 + nestedMessage.CalculateSize());
+            output.WriteTag(2, WireFormat.WireType.LengthDelimited);
+            output.WriteMessage(nestedMessage);
+            output.Flush();
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestMap.Parser,
+                memoryStream.ToArray(),
+                parsed =>
+                {
+                    Assert.AreEqual(nestedMessage, parsed.MapInt32ForeignMessage[0]);
+                });
+        }
+
+        [Test]
+        public void MapWithOnlyKey_PrimitiveValue()
+        {
+            // Hand-craft the stream to contain a single entry with just a key.
+            var memoryStream = new MemoryStream();
+            var output = new CodedOutputStream(memoryStream);
+            output.WriteTag(TestMap.MapInt32DoubleFieldNumber, WireFormat.WireType.LengthDelimited);
+            int key = 10;
+            output.WriteLength(1 + CodedOutputStream.ComputeInt32Size(key));
+            output.WriteTag(1, WireFormat.WireType.Varint);
+            output.WriteInt32(key);
+            output.Flush();
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestMap.Parser,
+                memoryStream.ToArray(),
+                parsed =>
+                {
+                    Assert.AreEqual(0.0, parsed.MapInt32Double[key]);
+                });
+        }
+
+        [Test]
+        public void MapWithOnlyKey_MessageValue()
+        {
+            // Hand-craft the stream to contain a single entry with just a key.
+            var memoryStream = new MemoryStream();
+            var output = new CodedOutputStream(memoryStream);
+            output.WriteTag(TestMap.MapInt32ForeignMessageFieldNumber, WireFormat.WireType.LengthDelimited);
+            int key = 10;
+            output.WriteLength(1 + CodedOutputStream.ComputeInt32Size(key));
+            output.WriteTag(1, WireFormat.WireType.Varint);
+            output.WriteInt32(key);
+            output.Flush();
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestMap.Parser,
+                memoryStream.ToArray(),
+                parsed =>
+                {
+                    Assert.AreEqual(new ForeignMessage(), parsed.MapInt32ForeignMessage[key]);
+                });
+        }
+
+        [Test]
+        public void MapIgnoresExtraFieldsWithinEntryMessages()
+        {
+            // Hand-craft the stream to contain a single entry with three fields
+            var memoryStream = new MemoryStream();
+            var output = new CodedOutputStream(memoryStream);
+
+            output.WriteTag(TestMap.MapInt32Int32FieldNumber, WireFormat.WireType.LengthDelimited);
+
+            var key = 10; // Field 1 
+            var value = 20; // Field 2
+            var extra = 30; // Field 3
+
+            // Each field can be represented in a single byte, with a single byte tag.
+            // Total message size: 6 bytes.
+            output.WriteLength(6);
+            output.WriteTag(1, WireFormat.WireType.Varint);
+            output.WriteInt32(key);
+            output.WriteTag(2, WireFormat.WireType.Varint);
+            output.WriteInt32(value);
+            output.WriteTag(3, WireFormat.WireType.Varint);
+            output.WriteInt32(extra);
+            output.Flush();
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestMap.Parser,
+                memoryStream.ToArray(),
+                parsed =>
+                {
+                    Assert.AreEqual(value, parsed.MapInt32Int32[key]);
+                });
+        }
+
+        [Test]
+        public void MapFieldOrderIsIrrelevant()
+        {
+            var memoryStream = new MemoryStream();
+            var output = new CodedOutputStream(memoryStream);
+
+            output.WriteTag(TestMap.MapInt32Int32FieldNumber, WireFormat.WireType.LengthDelimited);
+
+            var key = 10;
+            var value = 20;
+
+            // Each field can be represented in a single byte, with a single byte tag.
+            // Total message size: 4 bytes.
+            output.WriteLength(4);
+            output.WriteTag(2, WireFormat.WireType.Varint);
+            output.WriteInt32(value);
+            output.WriteTag(1, WireFormat.WireType.Varint);
+            output.WriteInt32(key);
+            output.Flush();
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestMap.Parser,
+                memoryStream.ToArray(),
+                parsed =>
+                {
+                    Assert.AreEqual(value, parsed.MapInt32Int32[key]);
+                });
+        }
+
+        [Test]
+        public void MapNonContiguousEntries()
+        {
+            var memoryStream = new MemoryStream();
+            var output = new CodedOutputStream(memoryStream);
+
+            // Message structure:
+            // Entry for MapInt32Int32
+            // Entry for MapStringString
+            // Entry for MapInt32Int32
+
+            // First entry
+            var key1 = 10;
+            var value1 = 20;
+            output.WriteTag(TestMap.MapInt32Int32FieldNumber, WireFormat.WireType.LengthDelimited);
+            output.WriteLength(4);
+            output.WriteTag(1, WireFormat.WireType.Varint);
+            output.WriteInt32(key1);
+            output.WriteTag(2, WireFormat.WireType.Varint);
+            output.WriteInt32(value1);
+
+            // Second entry
+            var key2 = "a";
+            var value2 = "b";
+            output.WriteTag(TestMap.MapStringStringFieldNumber, WireFormat.WireType.LengthDelimited);
+            output.WriteLength(6); // 3 bytes per entry: tag, size, character
+            output.WriteTag(1, WireFormat.WireType.LengthDelimited);
+            output.WriteString(key2);
+            output.WriteTag(2, WireFormat.WireType.LengthDelimited);
+            output.WriteString(value2);
+
+            // Third entry
+            var key3 = 15;
+            var value3 = 25;
+            output.WriteTag(TestMap.MapInt32Int32FieldNumber, WireFormat.WireType.LengthDelimited);
+            output.WriteLength(4);
+            output.WriteTag(1, WireFormat.WireType.Varint);
+            output.WriteInt32(key3);
+            output.WriteTag(2, WireFormat.WireType.Varint);
+            output.WriteInt32(value3);
+
+            output.Flush();
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestMap.Parser,
+                memoryStream.ToArray(),
+                parsed =>
+                {
+                    var expected = new TestMap
+                    {
+                        MapInt32Int32 = { { key1, value1 }, { key3, value3 } },
+                        MapStringString = { { key2, value2 } }
+                    };
+                    Assert.AreEqual(expected, parsed);
+                });
+        }
+
+        [Test]
+        public void DuplicateKeys_LastEntryWins()
+        {
+            var memoryStream = new MemoryStream();
+            var output = new CodedOutputStream(memoryStream);
+
+            var key = 10;
+            var value1 = 20;
+            var value2 = 30;
+
+            // First entry
+            output.WriteTag(TestMap.MapInt32Int32FieldNumber, WireFormat.WireType.LengthDelimited);
+            output.WriteLength(4);
+            output.WriteTag(1, WireFormat.WireType.Varint);
+            output.WriteInt32(key);
+            output.WriteTag(2, WireFormat.WireType.Varint);
+            output.WriteInt32(value1);
+
+            // Second entry - same key, different value
+            output.WriteTag(TestMap.MapInt32Int32FieldNumber, WireFormat.WireType.LengthDelimited);
+            output.WriteLength(4);
+            output.WriteTag(1, WireFormat.WireType.Varint);
+            output.WriteInt32(key);
+            output.WriteTag(2, WireFormat.WireType.Varint);
+            output.WriteInt32(value2);
+            output.Flush();
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestMap.Parser,
+                memoryStream.ToArray(),
+                parsed =>
+                {
+                    Assert.AreEqual(value2, parsed.MapInt32Int32[key]);
+                });
+        }
+
+        [Test]
+        public void CloneSingleNonMessageValues()
+        {
+            var original = new TestAllTypes
+            {
+                SingleBool = true,
+                SingleBytes = ByteString.CopyFrom(1, 2, 3, 4),
+                SingleDouble = 23.5,
+                SingleFixed32 = 23,
+                SingleFixed64 = 1234567890123,
+                SingleFloat = 12.25f,
+                SingleInt32 = 100,
+                SingleInt64 = 3210987654321,
+                SingleNestedEnum = TestAllTypes.Types.NestedEnum.Foo,
+                SingleSfixed32 = -123,
+                SingleSfixed64 = -12345678901234,
+                SingleSint32 = -456,
+                SingleSint64 = -12345678901235,
+                SingleString = "test",
+                SingleUint32 = uint.MaxValue,
+                SingleUint64 = ulong.MaxValue
+            };
+            var clone = original.Clone();
+            Assert.AreNotSame(original, clone);
+            Assert.AreEqual(original, clone);
+            // Just as a single example
+            clone.SingleInt32 = 150;
+            Assert.AreNotEqual(original, clone);
+        }
+
+        [Test]
+        public void CloneRepeatedNonMessageValues()
+        {
+            var original = new TestAllTypes
+            {
+                RepeatedBool = { true, false },
+                RepeatedBytes = { ByteString.CopyFrom(1, 2, 3, 4), ByteString.CopyFrom(5, 6) },
+                RepeatedDouble = { -12.25, 23.5 },
+                RepeatedFixed32 = { uint.MaxValue, 23 },
+                RepeatedFixed64 = { ulong.MaxValue, 1234567890123 },
+                RepeatedFloat = { 100f, 12.25f },
+                RepeatedInt32 = { 100, 200 },
+                RepeatedInt64 = { 3210987654321, long.MaxValue },
+                RepeatedNestedEnum = { TestAllTypes.Types.NestedEnum.Foo, TestAllTypes.Types.NestedEnum.Neg },
+                RepeatedSfixed32 = { -123, 123 },
+                RepeatedSfixed64 = { -12345678901234, 12345678901234 },
+                RepeatedSint32 = { -456, 100 },
+                RepeatedSint64 = { -12345678901235, 123 },
+                RepeatedString = { "foo", "bar" },
+                RepeatedUint32 = { uint.MaxValue, uint.MinValue },
+                RepeatedUint64 = { ulong.MaxValue, uint.MinValue }
+            };
+
+            var clone = original.Clone();
+            Assert.AreNotSame(original, clone);
+            Assert.AreEqual(original, clone);
+            // Just as a single example
+            clone.RepeatedDouble.Add(25.5);
+            Assert.AreNotEqual(original, clone);
+        }
+
+        [Test]
+        public void CloneSingleMessageField()
+        {
+            var original = new TestAllTypes
+            {
+                SingleNestedMessage = new TestAllTypes.Types.NestedMessage { Bb = 20 }
+            };
+
+            var clone = original.Clone();
+            Assert.AreNotSame(original, clone);
+            Assert.AreNotSame(original.SingleNestedMessage, clone.SingleNestedMessage);
+            Assert.AreEqual(original, clone);
+
+            clone.SingleNestedMessage.Bb = 30;
+            Assert.AreNotEqual(original, clone);
+        }
+
+        [Test]
+        public void CloneRepeatedMessageField()
+        {
+            var original = new TestAllTypes
+            {
+                RepeatedNestedMessage = { new TestAllTypes.Types.NestedMessage { Bb = 20 } }
+            };
+
+            var clone = original.Clone();
+            Assert.AreNotSame(original, clone);
+            Assert.AreNotSame(original.RepeatedNestedMessage, clone.RepeatedNestedMessage);
+            Assert.AreNotSame(original.RepeatedNestedMessage[0], clone.RepeatedNestedMessage[0]);
+            Assert.AreEqual(original, clone);
+
+            clone.RepeatedNestedMessage[0].Bb = 30;
+            Assert.AreNotEqual(original, clone);
+        }
+
+        [Test]
+        public void CloneOneofField()
+        {
+            var original = new TestAllTypes
+            {
+                OneofNestedMessage = new TestAllTypes.Types.NestedMessage { Bb = 20 }
+            };
+
+            var clone = original.Clone();
+            Assert.AreNotSame(original, clone);
+            Assert.AreEqual(original, clone);
+
+            // We should have cloned the message
+            original.OneofNestedMessage.Bb = 30;
+            Assert.AreNotEqual(original, clone);
+        }
+
+        [Test]
+        public void OneofProperties()
+        {
+            // Switch the oneof case between each of the different options, and check everything behaves
+            // as expected in each case.
+            var message = new TestAllTypes();
+            Assert.AreEqual("", message.OneofString);
+            Assert.AreEqual(0, message.OneofUint32);
+            Assert.AreEqual(ByteString.Empty, message.OneofBytes);
+            Assert.IsNull(message.OneofNestedMessage);
+            Assert.AreEqual(TestAllTypes.OneofFieldOneofCase.None, message.OneofFieldCase);
+
+            message.OneofString = "sample";
+            Assert.AreEqual("sample", message.OneofString);
+            Assert.AreEqual(0, message.OneofUint32);
+            Assert.AreEqual(ByteString.Empty, message.OneofBytes);
+            Assert.IsNull(message.OneofNestedMessage);
+            Assert.AreEqual(TestAllTypes.OneofFieldOneofCase.OneofString, message.OneofFieldCase);
+
+            var bytes = ByteString.CopyFrom(1, 2, 3);
+            message.OneofBytes = bytes;
+            Assert.AreEqual("", message.OneofString);
+            Assert.AreEqual(0, message.OneofUint32);
+            Assert.AreEqual(bytes, message.OneofBytes);
+            Assert.IsNull(message.OneofNestedMessage);
+            Assert.AreEqual(TestAllTypes.OneofFieldOneofCase.OneofBytes, message.OneofFieldCase);
+
+            message.OneofUint32 = 20;
+            Assert.AreEqual("", message.OneofString);
+            Assert.AreEqual(20, message.OneofUint32);
+            Assert.AreEqual(ByteString.Empty, message.OneofBytes);
+            Assert.IsNull(message.OneofNestedMessage);
+            Assert.AreEqual(TestAllTypes.OneofFieldOneofCase.OneofUint32, message.OneofFieldCase);
+
+            var nestedMessage = new TestAllTypes.Types.NestedMessage { Bb = 25 };
+            message.OneofNestedMessage = nestedMessage;
+            Assert.AreEqual("", message.OneofString);
+            Assert.AreEqual(0, message.OneofUint32);
+            Assert.AreEqual(ByteString.Empty, message.OneofBytes);
+            Assert.AreEqual(nestedMessage, message.OneofNestedMessage);
+            Assert.AreEqual(TestAllTypes.OneofFieldOneofCase.OneofNestedMessage, message.OneofFieldCase);
+
+            message.ClearOneofField();
+            Assert.AreEqual("", message.OneofString);
+            Assert.AreEqual(0, message.OneofUint32);
+            Assert.AreEqual(ByteString.Empty, message.OneofBytes);
+            Assert.IsNull(message.OneofNestedMessage);
+            Assert.AreEqual(TestAllTypes.OneofFieldOneofCase.None, message.OneofFieldCase);
+        }
+
+        [Test]
+        public void Oneof_DefaultValuesNotEqual()
+        {
+            var message1 = new TestAllTypes { OneofString = "" };
+            var message2 = new TestAllTypes { OneofUint32 = 0 };
+            Assert.AreEqual(TestAllTypes.OneofFieldOneofCase.OneofString, message1.OneofFieldCase);
+            Assert.AreEqual(TestAllTypes.OneofFieldOneofCase.OneofUint32, message2.OneofFieldCase);
+            Assert.AreNotEqual(message1, message2);
+        }
+
+        [Test]
+        public void OneofSerialization_NonDefaultValue()
+        {
+            var message = new TestAllTypes
+            {
+                OneofString = "this would take a bit of space",
+                OneofUint32 = 10
+            };
+            var bytes = message.ToByteArray();
+            Assert.AreEqual(3, bytes.Length); // 2 bytes for the tag + 1 for the value - no string!
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertRoundtrip(TestAllTypes.Parser, message, parsedMessage =>
+            {
+                Assert.AreEqual(TestAllTypes.OneofFieldOneofCase.OneofUint32, parsedMessage.OneofFieldCase);
+            });
+        }
+
+        [Test]
+        public void OneofSerialization_DefaultValue()
+        {
+            var message = new TestAllTypes
+            {
+                OneofString = "this would take a bit of space",
+                OneofUint32 = 0 // This is the default value for UInt32; normally wouldn't be serialized
+            };
+            var bytes = message.ToByteArray();
+            Assert.AreEqual(3, bytes.Length); // 2 bytes for the tag + 1 for the value - it's still serialized
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertRoundtrip(TestAllTypes.Parser, message, parsedMessage =>
+            {
+                Assert.AreEqual(TestAllTypes.OneofFieldOneofCase.OneofUint32, parsedMessage.OneofFieldCase);
+            });
+        }
+
+        [Test]
+        public void DiscardUnknownFields_RealDataStillRead()
+        {
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            var unusedFieldNumber = 23456;
+            Assert.IsFalse(TestAllTypes.Descriptor.Fields.InDeclarationOrder().Select(x => x.FieldNumber).Contains(unusedFieldNumber));
+            output.WriteTag(unusedFieldNumber, WireFormat.WireType.LengthDelimited);
+            output.WriteString("ignore me");
+            message.WriteTo(output);
+            output.Flush();
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestAllTypes.Parser,
+                stream.ToArray(),
+                parsed =>
+                {
+                    // TODO(jieluo): Add test back when DiscardUnknownFields API is supported.
+                    // Assert.AreEqual(message, parsed);
+                });
+        }
+
+        [Test]
+        public void DiscardUnknownFields_AllTypes()
+        {
+            // Simple way of ensuring we can skip all kinds of fields.
+            var data = SampleMessages.CreateFullTestAllTypes().ToByteArray();
+            var empty = Empty.Parser.ParseFrom(data);
+
+            MessageParsingHelpers.AssertReadingMessage(
+                Empty.Parser,
+                data,
+                parsed =>
+                {
+                    // TODO(jieluo): Add test back when DiscardUnknownFields API is supported.
+                    // Assert.AreNotEqual(new Empty(), empty);
+                });
+        }
+
+        // This was originally seen as a conformance test failure.
+        [Test]
+        public void TruncatedMessageFieldThrows()
+        {
+            // 130, 3 is the message tag
+            // 1 is the data length - but there's no data.
+            var data = new byte[] { 130, 3, 1 };
+            MessageParsingHelpers.AssertReadingMessageThrows<TestAllTypes, InvalidProtocolBufferException>(TestAllTypes.Parser, data);
+        }
+
+        /// <summary>
+        /// Demonstrates current behaviour with an extraneous end group tag - see issue 688
+        /// for details; we may want to change this.
+        /// </summary>
+        [Test]
+        public void ExtraEndGroupThrows()
+        {
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+
+            output.WriteTag(TestAllTypes.SingleFixed32FieldNumber, WireFormat.WireType.Fixed32);
+            output.WriteFixed32(123);
+            output.WriteTag(100, WireFormat.WireType.EndGroup);
+
+            output.Flush();
+
+            stream.Position = 0;
+            MessageParsingHelpers.AssertReadingMessageThrows<TestAllTypes, InvalidProtocolBufferException>(TestAllTypes.Parser, stream.ToArray());
+        }
+
+        [Test]
+        public void CustomDiagnosticMessage_DirectToStringCall()
+        {
+            var message = new ForeignMessage { C = 31 };
+            Assert.AreEqual("{ \"c\": 31, \"@cInHex\": \"1f\" }", message.ToString());
+            Assert.AreEqual("{ \"c\": 31 }", JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        public void CustomDiagnosticMessage_Nested()
+        {
+            var message = new TestAllTypes { SingleForeignMessage = new ForeignMessage { C = 16 } };
+            Assert.AreEqual("{ \"singleForeignMessage\": { \"c\": 16, \"@cInHex\": \"10\" } }", message.ToString());
+            Assert.AreEqual("{ \"singleForeignMessage\": { \"c\": 16 } }", JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        public void CustomDiagnosticMessage_DirectToTextWriterCall()
+        {
+            var message = new ForeignMessage { C = 31 };
+            var writer = new StringWriter();
+            JsonFormatter.Default.Format(message, writer);
+            Assert.AreEqual("{ \"c\": 31 }", writer.ToString());
+        }
+
+        [Test]
+        public void NaNComparisons()
+        {
+            var message1 = new TestAllTypes { SingleDouble = SampleNaNs.Regular };
+            var message2 = new TestAllTypes { SingleDouble = SampleNaNs.PayloadFlipped };
+            var message3 = new TestAllTypes { SingleDouble = SampleNaNs.Regular };
+
+            EqualityTester.AssertInequality(message1, message2);
+            EqualityTester.AssertEquality(message1, message3);
+        }
+
+        [Test]
+        [TestCase(false)]
+        [TestCase(true)]
+        public void MapFieldMerging(bool direct)
+        {
+            var message1 = new TestMap
+            {
+                MapStringString =
+                {
+                    { "x1", "y1" },
+                    { "common", "message1" }
+                }
+            };
+            var message2 = new TestMap
+            {
+                MapStringString =
+                {
+                    { "x2", "y2" },
+                    { "common", "message2" }
+                }
+            };
+            if (direct)
+            {
+                message1.MergeFrom(message2);
+            }
+            else
+            {
+                message1.MergeFrom(message2.ToByteArray());
+            }
+
+            var expected = new MapField<string, string>
+            {
+                { "x1", "y1" },
+                { "x2", "y2" },
+                { "common", "message2" }
+            };
+            Assert.AreEqual(expected, message1.MapStringString);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/Google.Protobuf.Test.csproj

@@ -0,0 +1,31 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>net462;netcoreapp3.1;net60</TargetFrameworks>
+    <AssemblyOriginatorKeyFile>../../keys/Google.Protobuf.snk</AssemblyOriginatorKeyFile>
+    <SignAssembly>true</SignAssembly>
+    <IsPackable>False</IsPackable>
+    <AllowUnsafeBlocks>True</AllowUnsafeBlocks>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Google.Protobuf\Google.Protobuf.csproj" />
+    <ProjectReference Include="..\Google.Protobuf.Test.TestProtos\Google.Protobuf.Test.TestProtos.csproj"/>
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.1.0" />
+    <PackageReference Include="NUnit" Version="3.13.3" />
+    <PackageReference Include="NUnit3TestAdapter" Version="4.2.1" />
+  </ItemGroup>
+
+  <!-- Needed for the net45 build to work on Unix. See https://github.com/dotnet/designs/pull/33 -->
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.2" PrivateAssets="All" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <EmbeddedResource Include="testprotos.pb" />
+  </ItemGroup>
+
+</Project>

libs/protobuf/csharp/src/Google.Protobuf.Test/IssuesTest.cs

@@ -0,0 +1,132 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using Google.Protobuf.Reflection;
+using UnitTest.Issues.TestProtos;
+using NUnit.Framework;
+using System.IO;
+using static UnitTest.Issues.TestProtos.OneofMerging.Types;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Tests for issues which aren't easily compartmentalized into other unit tests.
+    /// </summary>
+    public class IssuesTest
+    {
+        // Issue 45
+        [Test]
+        public void FieldCalledItem()
+        {
+            ItemField message = new ItemField { Item = 3 };
+            FieldDescriptor field = ItemField.Descriptor.FindFieldByName("item");
+            Assert.NotNull(field);
+            Assert.AreEqual(3, (int)field.Accessor.GetValue(message));
+        }
+
+        [Test]
+        public void ReservedNames()
+        {
+            var message = new ReservedNames { Types_ = 10, Descriptor_ = 20 };
+            // Underscores aren't reflected in the JSON.
+            Assert.AreEqual("{ \"types\": 10, \"descriptor\": 20 }", message.ToString());
+        }
+
+        [Test]
+        public void JsonNameParseTest()
+        {
+            var settings = new JsonParser.Settings(10, TypeRegistry.FromFiles(UnittestIssuesReflection.Descriptor));
+            var parser = new JsonParser(settings);
+
+            // It is safe to use either original field name or explicitly specified json_name
+            Assert.AreEqual(new TestJsonName { Name = "test", Description = "test2", Guid = "test3" },
+                parser.Parse<TestJsonName>("{ \"name\": \"test\", \"desc\": \"test2\", \"guid\": \"test3\" }"));
+        }
+
+        [Test]
+        public void JsonNameFormatTest()
+        {
+            var message = new TestJsonName { Name = "test", Description = "test2", Guid = "test3" };
+            Assert.AreEqual("{ \"name\": \"test\", \"desc\": \"test2\", \"exid\": \"test3\" }",
+                JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        public void OneofMerging()
+        {
+            var message1 = new OneofMerging { Nested = new Nested { X = 10 } };
+            var message2 = new OneofMerging { Nested = new Nested { Y = 20 } };
+            var expected = new OneofMerging { Nested = new Nested { X = 10, Y = 20 } };
+
+            var merged = message1.Clone();
+            merged.MergeFrom(message2);
+            Assert.AreEqual(expected, merged);
+        }
+
+        // Check that a tag immediately followed by end of limit can still be read.
+        [Test]
+        public void CodedInputStream_LimitReachedRightAfterTag()
+        {
+            MemoryStream ms = new MemoryStream();
+            var cos = new CodedOutputStream(ms);
+            cos.WriteTag(11, WireFormat.WireType.Varint);
+            Assert.AreEqual(1, cos.Position);
+            cos.WriteString("some extra padding");  // ensure is currentLimit distinct from the end of the buffer.
+            cos.Flush();
+
+            var cis = new CodedInputStream(ms.ToArray());
+            cis.PushLimit(1);  // make sure we reach the limit right after reading the tag.
+
+            // we still must read the tag correctly, even though the tag is at the very end of our limited input
+            // (which is a corner case and will most likely result in an error when trying to read value of the field
+            // described by this tag, but it would be a logical error not to read the tag that's actually present).
+            // See https://github.com/protocolbuffers/protobuf/pull/7289
+            cis.AssertNextTag(WireFormat.MakeTag(11, WireFormat.WireType.Varint));
+        }
+
+        [Test]
+        public void NoneFieldInOneof()
+        {
+            var message = new OneofWithNoneField();
+            var emptyHashCode = message.GetHashCode();
+            Assert.AreEqual(OneofWithNoneField.TestOneofCase.None, message.TestCase);
+            message.None = "test";
+            Assert.AreEqual(OneofWithNoneField.TestOneofCase.None_, message.TestCase);
+            Assert.AreNotEqual(emptyHashCode, message.GetHashCode());
+
+            var bytes = message.ToByteArray();
+            var parsed = OneofWithNoneField.Parser.ParseFrom(bytes);
+            Assert.AreEqual(message, parsed);
+            Assert.AreEqual("test", parsed.None);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/JsonFormatterSettingsTest.cs

@@ -0,0 +1,111 @@
+#region Copyright notice and license
+
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using Google.Protobuf.Reflection;
+using NUnit.Framework;
+
+// For WrapInQuotes
+
+namespace Google.Protobuf
+{
+    public class JsonFormatterSettingsTest
+    {
+        [Test]
+        public void WithIndentation()
+        {
+            var settings = JsonFormatter.Settings.Default.WithIndentation("\t");
+            Assert.AreEqual("\t", settings.Indentation);
+        }
+
+        [Test]
+        public void WithTypeRegistry()
+        {
+            var typeRegistry = TypeRegistry.Empty;
+            var settings = JsonFormatter.Settings.Default.WithTypeRegistry(typeRegistry);
+            Assert.AreEqual(typeRegistry, settings.TypeRegistry);
+        }
+
+        [Test]
+        public void WithFormatDefaultValues()
+        {
+            var settingsWith = JsonFormatter.Settings.Default.WithFormatDefaultValues(true);
+            Assert.AreEqual(true, settingsWith.FormatDefaultValues);
+
+            var settingsWithout = JsonFormatter.Settings.Default.WithFormatDefaultValues(false);
+            Assert.AreEqual(false, settingsWithout.FormatDefaultValues);
+        }
+
+        [Test]
+        public void WithFormatEnumsAsIntegers()
+        {
+            var settingsWith = JsonFormatter.Settings.Default.WithFormatEnumsAsIntegers(true);
+            Assert.AreEqual(true, settingsWith.FormatEnumsAsIntegers);
+
+            var settingsWithout = JsonFormatter.Settings.Default.WithFormatEnumsAsIntegers(false);
+            Assert.AreEqual(false, settingsWithout.FormatEnumsAsIntegers);
+        }
+
+        [Test]
+        public void WithMethodsPreserveExistingSettings()
+        {
+            var typeRegistry = TypeRegistry.Empty;
+            var baseSettings = JsonFormatter.Settings.Default
+                .WithIndentation("\t")
+                .WithFormatDefaultValues(true)
+                .WithFormatEnumsAsIntegers(true)
+                .WithTypeRegistry(typeRegistry)
+                .WithPreserveProtoFieldNames(true);
+
+            var settings1 = baseSettings.WithIndentation("\t");
+            var settings2 = baseSettings.WithFormatDefaultValues(true);
+            var settings3 = baseSettings.WithFormatEnumsAsIntegers(true);
+            var settings4 = baseSettings.WithTypeRegistry(typeRegistry);
+            var settings5 = baseSettings.WithPreserveProtoFieldNames(true);
+
+            AssertAreEqual(baseSettings, settings1);
+            AssertAreEqual(baseSettings, settings2);
+            AssertAreEqual(baseSettings, settings3);
+            AssertAreEqual(baseSettings, settings4);
+            AssertAreEqual(baseSettings, settings5);
+        }
+
+        private static void AssertAreEqual(JsonFormatter.Settings settings, JsonFormatter.Settings other)
+        {
+            Assert.AreEqual(settings.Indentation, other.Indentation);
+            Assert.AreEqual(settings.FormatDefaultValues, other.FormatDefaultValues);
+            Assert.AreEqual(settings.FormatEnumsAsIntegers, other.FormatEnumsAsIntegers);
+            Assert.AreEqual(settings.TypeRegistry, other.TypeRegistry);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/JsonFormatterTest.cs

@@ -0,0 +1,901 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using Google.Protobuf.TestProtos;
+using NUnit.Framework;
+using UnitTest.Issues.TestProtos;
+using Google.Protobuf.WellKnownTypes;
+using Google.Protobuf.Reflection;
+
+using static Google.Protobuf.JsonParserTest; // For WrapInQuotes
+using System.IO;
+using Google.Protobuf.Collections;
+using ProtobufUnittest;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Tests for the JSON formatter. Note that in these tests, double quotes are replaced with apostrophes
+    /// for the sake of readability (embedding \" everywhere is painful). See the AssertJson method for details.
+    /// </summary>
+    public class JsonFormatterTest
+    {
+        [Test]
+        public void DefaultValues_WhenOmitted()
+        {
+            var formatter = JsonFormatter.Default;
+
+            AssertJson("{ }", formatter.Format(new ForeignMessage()));
+            AssertJson("{ }", formatter.Format(new TestAllTypes()));
+            AssertJson("{ }", formatter.Format(new TestMap()));
+        }
+
+        [Test]
+        public void DefaultValues_WhenIncluded()
+        {
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithFormatDefaultValues(true));
+            AssertJson("{ 'c': 0 }", formatter.Format(new ForeignMessage()));
+        }
+
+        [Test]
+        public void EnumAllowAlias()
+        {
+            var message = new TestEnumAllowAlias
+            {
+                Value = TestEnumWithDupValue.Foo2,
+            };
+            var actualText = JsonFormatter.Default.Format(message);
+            var expectedText = "{ 'value': 'FOO1' }";
+            AssertJson(expectedText, actualText);
+        }
+
+        [Test]
+        public void EnumAsInt()
+        {
+            var message = new TestAllTypes
+            {
+                SingleForeignEnum = ForeignEnum.ForeignBar,
+                RepeatedForeignEnum = { ForeignEnum.ForeignBaz, (ForeignEnum) 100, ForeignEnum.ForeignFoo }
+            };
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithFormatEnumsAsIntegers(true));
+            var actualText = formatter.Format(message);
+            var expectedText = "{ " +
+                               "'singleForeignEnum': 5, " +
+                               "'repeatedForeignEnum': [ 6, 100, 4 ]" +
+                               " }";
+            AssertJson(expectedText, actualText);
+        }
+
+        [Test]
+        public void AllSingleFields()
+        {
+            var message = new TestAllTypes
+            {
+                SingleBool = true,
+                SingleBytes = ByteString.CopyFrom(1, 2, 3, 4),
+                SingleDouble = 23.5,
+                SingleFixed32 = 23,
+                SingleFixed64 = 1234567890123,
+                SingleFloat = 12.25f,
+                SingleForeignEnum = ForeignEnum.ForeignBar,
+                SingleForeignMessage = new ForeignMessage { C = 10 },
+                SingleImportEnum = ImportEnum.ImportBaz,
+                SingleImportMessage = new ImportMessage { D = 20 },
+                SingleInt32 = 100,
+                SingleInt64 = 3210987654321,
+                SingleNestedEnum = TestAllTypes.Types.NestedEnum.Foo,
+                SingleNestedMessage = new TestAllTypes.Types.NestedMessage { Bb = 35 },
+                SinglePublicImportMessage = new PublicImportMessage { E = 54 },
+                SingleSfixed32 = -123,
+                SingleSfixed64 = -12345678901234,
+                SingleSint32 = -456,
+                SingleSint64 = -12345678901235,
+                SingleString = "test\twith\ttabs",
+                SingleUint32 = uint.MaxValue,
+                SingleUint64 = ulong.MaxValue,
+            };
+            var actualText = JsonFormatter.Default.Format(message);
+
+            // Fields in numeric order
+            var expectedText = "{ " +
+                "'singleInt32': 100, " +
+                "'singleInt64': '3210987654321', " +
+                "'singleUint32': 4294967295, " +
+                "'singleUint64': '18446744073709551615', " +
+                "'singleSint32': -456, " +
+                "'singleSint64': '-12345678901235', " +
+                "'singleFixed32': 23, " +
+                "'singleFixed64': '1234567890123', " +
+                "'singleSfixed32': -123, " +
+                "'singleSfixed64': '-12345678901234', " +
+                "'singleFloat': 12.25, " +
+                "'singleDouble': 23.5, " +
+                "'singleBool': true, " +
+                "'singleString': 'test\\twith\\ttabs', " +
+                "'singleBytes': 'AQIDBA==', " +
+                "'singleNestedMessage': { 'bb': 35 }, " +
+                "'singleForeignMessage': { 'c': 10 }, " +
+                "'singleImportMessage': { 'd': 20 }, " +
+                "'singleNestedEnum': 'FOO', " +
+                "'singleForeignEnum': 'FOREIGN_BAR', " +
+                "'singleImportEnum': 'IMPORT_BAZ', " +
+                "'singlePublicImportMessage': { 'e': 54 }" +
+                " }";
+            AssertJson(expectedText, actualText);
+        }
+
+        [Test]
+        public void WithFormatDefaultValues_DoesNotAffectMessageFields()
+        {
+            var message = new TestAllTypes();
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithFormatDefaultValues(true));
+            var json = formatter.Format(message);
+            Assert.IsFalse(json.Contains("\"singleNestedMessage\""));
+            Assert.IsFalse(json.Contains("\"singleForeignMessage\""));
+            Assert.IsFalse(json.Contains("\"singleImportMessage\""));
+        }
+
+        [Test]
+        public void WithFormatDefaultValues_DoesNotAffectProto3OptionalFields()
+        {
+            var message = new TestProto3Optional { OptionalInt32 = 0 };
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithFormatDefaultValues(true));
+            var json = formatter.Format(message);
+            // The non-optional proto3 fields are formatted, as is the optional-but-specified field.
+            AssertJson("{ 'optionalInt32': 0, 'singularInt32': 0, 'singularInt64': '0' }", json);
+        }
+
+        [Test]
+        public void WithFormatDefaultValues_DoesNotAffectProto2Fields()
+        {
+            var message = new TestProtos.Proto2.ForeignMessage { C = 0 };
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithFormatDefaultValues(true));
+            var json = formatter.Format(message);
+            // The specified field is formatted, but the non-specified field (d) is not.
+            AssertJson("{ 'c': 0 }", json);
+        }
+
+        [Test]
+        public void WithFormatDefaultValues_DoesNotAffectOneofFields()
+        {
+            var message = new TestOneof();
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithFormatDefaultValues(true));
+            var json = formatter.Format(message);
+            AssertJson("{ }", json);
+        }
+
+        [Test]
+        public void RepeatedField()
+        {
+            AssertJson("{ 'repeatedInt32': [ 1, 2, 3, 4, 5 ] }",
+                JsonFormatter.Default.Format(new TestAllTypes { RepeatedInt32 = { 1, 2, 3, 4, 5 } }));
+        }
+
+        [Test]
+        public void MapField_StringString()
+        {
+            AssertJson("{ 'mapStringString': { 'with spaces': 'bar', 'a': 'b' } }",
+                JsonFormatter.Default.Format(new TestMap { MapStringString = { { "with spaces", "bar" }, { "a", "b" } } }));
+        }
+
+        [Test]
+        public void MapField_Int32Int32()
+        {
+            // The keys are quoted, but the values aren't.
+            AssertJson("{ 'mapInt32Int32': { '0': 1, '2': 3 } }",
+                JsonFormatter.Default.Format(new TestMap { MapInt32Int32 = { { 0, 1 }, { 2, 3 } } }));
+        }
+
+        [Test]
+        public void MapField_BoolBool()
+        {
+            // The keys are quoted, but the values aren't.
+            AssertJson("{ 'mapBoolBool': { 'false': true, 'true': false } }",
+                JsonFormatter.Default.Format(new TestMap { MapBoolBool = { { false, true }, { true, false } } }));
+        }
+
+        [Test]
+        public void NullValueOutsideStruct()
+        {
+            var message = new NullValueOutsideStruct { NullValue = NullValue.NullValue };
+            AssertJson("{ 'nullValue': null }", JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        public void NullValueNotInOneof()
+        {
+            var message = new NullValueNotInOneof();
+            AssertJson("{ }", JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        public void NullValueNotInOneof_FormatDefaults()
+        {
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithFormatDefaultValues(true));
+            var message = new NullValueNotInOneof();
+            AssertJson("{ 'nullValue': null }", formatter.Format(message));
+        }
+
+        [TestCase(1.0, "1")]
+        [TestCase(double.NaN, "'NaN'")]
+        [TestCase(double.PositiveInfinity, "'Infinity'")]
+        [TestCase(double.NegativeInfinity, "'-Infinity'")]
+        public void DoubleRepresentations(double value, string expectedValueText)
+        {
+            var message = new TestAllTypes { SingleDouble = value };
+            string actualText = JsonFormatter.Default.Format(message);
+            string expectedText = "{ 'singleDouble': " + expectedValueText + " }";
+            AssertJson(expectedText, actualText);
+        }
+
+        [Test]
+        public void UnknownEnumValueNumeric_SingleField()
+        {
+            var message = new TestAllTypes { SingleForeignEnum = (ForeignEnum) 100 };
+            AssertJson("{ 'singleForeignEnum': 100 }", JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        public void UnknownEnumValueNumeric_RepeatedField()
+        {
+            var message = new TestAllTypes { RepeatedForeignEnum = { ForeignEnum.ForeignBaz, (ForeignEnum) 100, ForeignEnum.ForeignFoo } };
+            AssertJson("{ 'repeatedForeignEnum': [ 'FOREIGN_BAZ', 100, 'FOREIGN_FOO' ] }", JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        public void UnknownEnumValueNumeric_MapField()
+        {
+            var message = new TestMap { MapInt32Enum = { { 1, MapEnum.Foo }, { 2, (MapEnum) 100 }, { 3, MapEnum.Bar } } };
+            AssertJson("{ 'mapInt32Enum': { '1': 'MAP_ENUM_FOO', '2': 100, '3': 'MAP_ENUM_BAR' } }", JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        public void UnknownEnumValue_RepeatedField_AllEntriesUnknown()
+        {
+            var message = new TestAllTypes { RepeatedForeignEnum = { (ForeignEnum) 200, (ForeignEnum) 100 } };
+            AssertJson("{ 'repeatedForeignEnum': [ 200, 100 ] }", JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        [TestCase("a\u17b4b", "a\\u17b4b")] // Explicit
+        [TestCase("a\u0601b", "a\\u0601b")] // Ranged
+        [TestCase("a\u0605b", "a\u0605b")] // Passthrough (note lack of double backslash...)
+        public void SimpleNonAscii(string text, string encoded)
+        {
+            var message = new TestAllTypes { SingleString = text };
+            AssertJson("{ 'singleString': '" + encoded + "' }", JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        public void SurrogatePairEscaping()
+        {
+            var message = new TestAllTypes { SingleString = "a\uD801\uDC01b" };
+            AssertJson("{ 'singleString': 'a\\ud801\\udc01b' }", JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        public void InvalidSurrogatePairsFail()
+        {
+            // Note: don't use TestCase for these, as the strings can't be reliably represented
+            // See http://codeblog.jonskeet.uk/2014/11/07/when-is-a-string-not-a-string/
+
+            // Lone low surrogate
+            var message = new TestAllTypes { SingleString = "a\uDC01b" };
+            Assert.Throws<ArgumentException>(() => JsonFormatter.Default.Format(message));
+
+            // Lone high surrogate
+            message = new TestAllTypes { SingleString = "a\uD801b" };
+            Assert.Throws<ArgumentException>(() => JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        [TestCase("foo_bar", "fooBar")]
+        [TestCase("bananaBanana", "bananaBanana")]
+        [TestCase("BANANABanana", "BANANABanana")]
+        [TestCase("simple", "simple")]
+        [TestCase("ACTION_AND_ADVENTURE", "ACTIONANDADVENTURE")]
+        [TestCase("action_and_adventure", "actionAndAdventure")]
+        [TestCase("kFoo", "kFoo")]
+        [TestCase("HTTPServer", "HTTPServer")]
+        [TestCase("CLIENT", "CLIENT")]
+        public void ToJsonName(string original, string expected)
+        {
+            Assert.AreEqual(expected, JsonFormatter.ToJsonName(original));
+        }
+
+        [Test]
+        [TestCase(null, "{ }")]
+        [TestCase("x", "{ 'fooString': 'x' }")]
+        [TestCase("", "{ 'fooString': '' }")]
+        public void Oneof(string fooStringValue, string expectedJson)
+        {
+            var message = new TestOneof();
+            if (fooStringValue != null)
+            {
+                message.FooString = fooStringValue;
+            }
+
+            // We should get the same result both with and without "format default values".
+            var formatter = JsonFormatter.Default;
+            AssertJson(expectedJson, formatter.Format(message));
+            formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithFormatDefaultValues(true));
+            AssertJson(expectedJson, formatter.Format(message));
+        }
+
+        [Test]
+        public void WrapperFormatting_Single()
+        {
+            // Just a few examples, handling both classes and value types, and
+            // default vs non-default values
+            var message = new TestWellKnownTypes
+            {
+                Int64Field = 10,
+                Int32Field = 0,
+                BytesField = ByteString.FromBase64("ABCD"),
+                StringField = ""
+            };
+            var expectedJson = "{ 'int64Field': '10', 'int32Field': 0, 'stringField': '', 'bytesField': 'ABCD' }";
+            AssertJson(expectedJson, JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        public void WrapperFormatting_Message()
+        {
+            Assert.AreEqual("\"\"", JsonFormatter.Default.Format(new StringValue()));
+            Assert.AreEqual("0", JsonFormatter.Default.Format(new Int32Value()));
+        }
+
+        [Test]
+        public void WrapperFormatting_FormatDefaultValuesDoesNotFormatNull()
+        {
+            // The actual JSON here is very large because there are lots of fields. Just test a couple of them.
+            var message = new TestWellKnownTypes { Int32Field = 10 };
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithFormatDefaultValues(true));
+            var actualJson = formatter.Format(message);
+            // This *used* to include "int64Field": null, but that was a bug.
+            // WithDefaultValues should not affect message fields, including wrapper types.
+            Assert.IsFalse(actualJson.Contains("\"int64Field\": null"));
+            Assert.IsTrue(actualJson.Contains("\"int32Field\": 10"));
+        }
+
+        [Test]
+        public void OutputIsInNumericFieldOrder_NoDefaults()
+        {
+            var formatter = JsonFormatter.Default;
+            var message = new TestJsonFieldOrdering { PlainString = "p1", PlainInt32 = 2 };
+            AssertJson("{ 'plainString': 'p1', 'plainInt32': 2 }", formatter.Format(message));
+            message = new TestJsonFieldOrdering { O1Int32 = 5, O2String = "o2", PlainInt32 = 10, PlainString = "plain" };
+            AssertJson("{ 'plainString': 'plain', 'o2String': 'o2', 'plainInt32': 10, 'o1Int32': 5 }", formatter.Format(message));
+            message = new TestJsonFieldOrdering { O1String = "", O2Int32 = 0, PlainInt32 = 10, PlainString = "plain" };
+            AssertJson("{ 'plainString': 'plain', 'o1String': '', 'plainInt32': 10, 'o2Int32': 0 }", formatter.Format(message));
+        }
+
+        [Test]
+        public void OutputIsInNumericFieldOrder_WithDefaults()
+        {
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithFormatDefaultValues(true));
+            var message = new TestJsonFieldOrdering();
+            AssertJson("{ 'plainString': '', 'plainInt32': 0 }", formatter.Format(message));
+            message = new TestJsonFieldOrdering { O1Int32 = 5, O2String = "o2", PlainInt32 = 10, PlainString = "plain" };
+            AssertJson("{ 'plainString': 'plain', 'o2String': 'o2', 'plainInt32': 10, 'o1Int32': 5 }", formatter.Format(message));
+            message = new TestJsonFieldOrdering { O1String = "", O2Int32 = 0, PlainInt32 = 10, PlainString = "plain" };
+            AssertJson("{ 'plainString': 'plain', 'o1String': '', 'plainInt32': 10, 'o2Int32': 0 }", formatter.Format(message));
+        }
+
+        [Test]
+        [TestCase("1970-01-01T00:00:00Z", 0)]
+        [TestCase("1970-01-01T00:00:00.000000001Z", 1)]
+        [TestCase("1970-01-01T00:00:00.000000010Z", 10)]
+        [TestCase("1970-01-01T00:00:00.000000100Z", 100)]
+        [TestCase("1970-01-01T00:00:00.000001Z", 1000)]
+        [TestCase("1970-01-01T00:00:00.000010Z", 10000)]
+        [TestCase("1970-01-01T00:00:00.000100Z", 100000)]
+        [TestCase("1970-01-01T00:00:00.001Z", 1000000)]
+        [TestCase("1970-01-01T00:00:00.010Z", 10000000)]
+        [TestCase("1970-01-01T00:00:00.100Z", 100000000)]
+        [TestCase("1970-01-01T00:00:00.120Z", 120000000)]
+        [TestCase("1970-01-01T00:00:00.123Z", 123000000)]
+        [TestCase("1970-01-01T00:00:00.123400Z", 123400000)]
+        [TestCase("1970-01-01T00:00:00.123450Z", 123450000)]
+        [TestCase("1970-01-01T00:00:00.123456Z", 123456000)]
+        [TestCase("1970-01-01T00:00:00.123456700Z", 123456700)]
+        [TestCase("1970-01-01T00:00:00.123456780Z", 123456780)]
+        [TestCase("1970-01-01T00:00:00.123456789Z", 123456789)]
+        public void TimestampStandalone(string expected, int nanos)
+        {
+            Assert.AreEqual(WrapInQuotes(expected), new Timestamp { Nanos = nanos }.ToString());
+        }
+
+        [Test]
+        public void TimestampStandalone_FromDateTime()
+        {
+            // One before and one after the Unix epoch, more easily represented via DateTime.
+            Assert.AreEqual("\"1673-06-19T12:34:56Z\"",
+                new DateTime(1673, 6, 19, 12, 34, 56, DateTimeKind.Utc).ToTimestamp().ToString());
+            Assert.AreEqual("\"2015-07-31T10:29:34Z\"",
+                new DateTime(2015, 7, 31, 10, 29, 34, DateTimeKind.Utc).ToTimestamp().ToString());
+        }
+
+        [Test]
+        [TestCase(-1, -1)] // Would be valid as duration
+        [TestCase(1, Timestamp.MaxNanos + 1)]
+        [TestCase(Timestamp.UnixSecondsAtBclMaxValue + 1, 0)]
+        [TestCase(Timestamp.UnixSecondsAtBclMinValue - 1, 0)]
+        public void TimestampStandalone_NonNormalized(long seconds, int nanoseconds)
+        {
+            var timestamp = new Timestamp { Seconds = seconds, Nanos = nanoseconds };
+            Assert.Throws<InvalidOperationException>(() => JsonFormatter.Default.Format(timestamp));
+        }
+
+        [Test]
+        public void TimestampField()
+        {
+            var message = new TestWellKnownTypes { TimestampField = new Timestamp() };
+            AssertJson("{ 'timestampField': '1970-01-01T00:00:00Z' }", JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        [TestCase(0, 0, "0s")]
+        [TestCase(1, 0, "1s")]
+        [TestCase(-1, 0, "-1s")]
+        [TestCase(0, 1, "0.000000001s")]
+        [TestCase(0, 10, "0.000000010s")]
+        [TestCase(0, 100, "0.000000100s")]
+        [TestCase(0, 1000, "0.000001s")]
+        [TestCase(0, 10000, "0.000010s")]
+        [TestCase(0, 100000, "0.000100s")]
+        [TestCase(0, 1000000, "0.001s")]
+        [TestCase(0, 10000000, "0.010s")]
+        [TestCase(0, 100000000, "0.100s")]
+        [TestCase(0, 120000000, "0.120s")]
+        [TestCase(0, 123000000, "0.123s")]
+        [TestCase(0, 123400000, "0.123400s")]
+        [TestCase(0, 123450000, "0.123450s")]
+        [TestCase(0, 123456000, "0.123456s")]
+        [TestCase(0, 123456700, "0.123456700s")]
+        [TestCase(0, 123456780, "0.123456780s")]
+        [TestCase(0, 123456789, "0.123456789s")]
+        [TestCase(0, -100000000, "-0.100s")]
+        [TestCase(1, 100000000, "1.100s")]
+        [TestCase(-1, -100000000, "-1.100s")]
+        public void DurationStandalone(long seconds, int nanoseconds, string expected)
+        {
+            var json = JsonFormatter.Default.Format(new Duration { Seconds = seconds, Nanos = nanoseconds });
+            Assert.AreEqual(WrapInQuotes(expected), json);
+        }
+
+        [Test]
+        [TestCase(1, 2123456789)]
+        [TestCase(1, -100000000)]
+        public void DurationStandalone_NonNormalized(long seconds, int nanoseconds)
+        {
+            var duration = new Duration { Seconds = seconds, Nanos = nanoseconds };
+            Assert.Throws<InvalidOperationException>(() => JsonFormatter.Default.Format(duration));
+        }
+
+        [Test]
+        public void DurationField()
+        {
+            var message = new TestWellKnownTypes { DurationField = new Duration() };
+            AssertJson("{ 'durationField': '0s' }", JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        public void StructSample()
+        {
+            var message = new Struct
+            {
+                Fields =
+                {
+                    { "a", Value.ForNull() },
+                    { "b", Value.ForBool(false) },
+                    { "c", Value.ForNumber(10.5) },
+                    { "d", Value.ForString("text") },
+                    { "e", Value.ForList(Value.ForString("t1"), Value.ForNumber(5)) },
+                    { "f", Value.ForStruct(new Struct { Fields = { { "nested", Value.ForString("value") } } }) }
+                }
+            };
+            AssertJson("{ 'a': null, 'b': false, 'c': 10.5, 'd': 'text', 'e': [ 't1', 5 ], 'f': { 'nested': 'value' } }", message.ToString());
+        }
+
+        [Test]
+        [TestCase("foo__bar")]
+        [TestCase("foo_3_ar")]
+        [TestCase("fooBar")]
+        public void FieldMaskInvalid(string input)
+        {
+            var mask = new FieldMask { Paths = { input } };
+            Assert.Throws<InvalidOperationException>(() => JsonFormatter.Default.Format(mask));
+        }
+
+        [Test]
+        public void FieldMaskStandalone()
+        {
+            var fieldMask = new FieldMask { Paths = { "", "single", "with_underscore", "nested.field.name", "nested..double_dot" } };
+            Assert.AreEqual("\",single,withUnderscore,nested.field.name,nested..doubleDot\"", fieldMask.ToString());
+
+            // Invalid, but we shouldn't create broken JSON...
+            fieldMask = new FieldMask { Paths = { "x\\y" } };
+            Assert.AreEqual(@"""x\\y""", fieldMask.ToString());
+        }
+
+        [Test]
+        public void FieldMaskField()
+        {
+            var message = new TestWellKnownTypes { FieldMaskField = new FieldMask { Paths = { "user.display_name", "photo" } } };
+            AssertJson("{ 'fieldMaskField': 'user.displayName,photo' }", JsonFormatter.Default.Format(message));
+        }
+
+        // SourceContext is an example of a well-known type with no special JSON handling
+        [Test]
+        public void SourceContextStandalone()
+        {
+            var message = new SourceContext { FileName = "foo.proto" };
+            AssertJson("{ 'fileName': 'foo.proto' }", JsonFormatter.Default.Format(message));
+        }
+
+        [Test]
+        public void AnyWellKnownType()
+        {
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithTypeRegistry(TypeRegistry.FromMessages(Timestamp.Descriptor)));
+            var timestamp = new DateTime(1673, 6, 19, 12, 34, 56, DateTimeKind.Utc).ToTimestamp();
+            var any = Any.Pack(timestamp);
+            AssertJson("{ '@type': 'type.googleapis.com/google.protobuf.Timestamp', 'value': '1673-06-19T12:34:56Z' }", formatter.Format(any));
+        }
+
+        [Test]
+        public void AnyMessageType()
+        {
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithTypeRegistry(TypeRegistry.FromMessages(TestAllTypes.Descriptor)));
+            var message = new TestAllTypes { SingleInt32 = 10, SingleNestedMessage = new TestAllTypes.Types.NestedMessage { Bb = 20 } };
+            var any = Any.Pack(message);
+            AssertJson("{ '@type': 'type.googleapis.com/protobuf_unittest3.TestAllTypes', 'singleInt32': 10, 'singleNestedMessage': { 'bb': 20 } }", formatter.Format(any));
+        }
+
+        [Test]
+        public void AnyMessageType_CustomPrefix()
+        {
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithTypeRegistry(TypeRegistry.FromMessages(TestAllTypes.Descriptor)));
+            var message = new TestAllTypes { SingleInt32 = 10 };
+            var any = Any.Pack(message, "foo.bar/baz");
+            AssertJson("{ '@type': 'foo.bar/baz/protobuf_unittest3.TestAllTypes', 'singleInt32': 10 }", formatter.Format(any));
+        }
+
+        [Test]
+        public void AnyNested()
+        {
+            var registry = TypeRegistry.FromMessages(TestWellKnownTypes.Descriptor, TestAllTypes.Descriptor);
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithTypeRegistry(registry));
+
+            // Nest an Any as the value of an Any.
+            var doubleNestedMessage = new TestAllTypes { SingleInt32 = 20 };
+            var nestedMessage = Any.Pack(doubleNestedMessage);
+            var message = new TestWellKnownTypes { AnyField = Any.Pack(nestedMessage) };
+            AssertJson("{ 'anyField': { '@type': 'type.googleapis.com/google.protobuf.Any', 'value': { '@type': 'type.googleapis.com/protobuf_unittest3.TestAllTypes', 'singleInt32': 20 } } }",
+                formatter.Format(message));
+        }
+
+        [Test]
+        public void AnyUnknownType()
+        {
+            // The default type registry doesn't have any types in it.
+            var message = new TestAllTypes();
+            var any = Any.Pack(message);
+            Assert.Throws<InvalidOperationException>(() => JsonFormatter.Default.Format(any));
+        }
+
+        [Test]
+        [TestCase(typeof(BoolValue), true, "true")]
+        [TestCase(typeof(Int32Value), 32, "32")]
+        [TestCase(typeof(Int64Value), 32L, "\"32\"")]
+        [TestCase(typeof(UInt32Value), 32U, "32")]
+        [TestCase(typeof(UInt64Value), 32UL, "\"32\"")]
+        [TestCase(typeof(StringValue), "foo", "\"foo\"")]
+        [TestCase(typeof(FloatValue), 1.5f, "1.5")]
+        [TestCase(typeof(DoubleValue), 1.5d, "1.5")]
+        public void Wrappers_Standalone(System.Type wrapperType, object value, string expectedJson)
+        {
+            IMessage populated = (IMessage)Activator.CreateInstance(wrapperType);
+            populated.Descriptor.Fields[WrappersReflection.WrapperValueFieldNumber].Accessor.SetValue(populated, value);
+            Assert.AreEqual(expectedJson, JsonFormatter.Default.Format(populated));
+        }
+
+        // Sanity tests for WriteValue. Not particularly comprehensive, as it's all covered above already,
+        // as FormatMessage uses WriteValue.
+
+        [TestCase(null, "null")]
+        [TestCase(1, "1")]
+        [TestCase(1L, "'1'")]
+        [TestCase(0.5f, "0.5")]
+        [TestCase(0.5d, "0.5")]
+        [TestCase("text", "'text'")]
+        [TestCase("x\ny", @"'x\ny'")]
+        [TestCase(ForeignEnum.ForeignBar, "'FOREIGN_BAR'")]
+        public void WriteValue_Constant(object value, string expectedJson)
+        {
+            AssertWriteValue(value, expectedJson);
+        }
+
+        [Test]
+        public void WriteValue_Timestamp()
+        {
+            var value = new DateTime(1673, 6, 19, 12, 34, 56, DateTimeKind.Utc).ToTimestamp();
+            AssertWriteValue(value, "'1673-06-19T12:34:56Z'");
+        }
+
+        [Test]
+        public void WriteValue_Message()
+        {
+            var value = new TestAllTypes { SingleInt32 = 100, SingleInt64 = 3210987654321L };
+            AssertWriteValue(value, "{ 'singleInt32': 100, 'singleInt64': '3210987654321' }");
+        }
+
+        [Test]
+        public void WriteValue_Message_PreserveNames()
+        {
+            var value = new TestAllTypes { SingleInt32 = 100, SingleInt64 = 3210987654321L };
+            AssertWriteValue(value, "{ 'single_int32': 100, 'single_int64': '3210987654321' }", JsonFormatter.Settings.Default.WithPreserveProtoFieldNames(true));
+        }
+
+        [Test]
+        public void WriteValue_List()
+        {
+            var value = new RepeatedField<int> { 1, 2, 3 };
+            AssertWriteValue(value, "[ 1, 2, 3 ]");
+        }
+
+        [Test]
+        public void WriteValueWithIndentation_EmptyMessage()
+        {
+            var value = new TestEmptyMessage();
+
+            AssertWriteValue(value, "{}", JsonFormatter.Settings.Default.WithIndentation());
+        }
+
+        [Test]
+        public void WriteValueWithIndentation_NestedTestAllTypes()
+        {
+            var value = new NestedTestAllTypes
+            {
+                Payload = new TestAllTypes
+                {
+                    SingleBool = true,
+                    SingleInt32 = 100,
+                    SingleString = "multiple fields",
+                    RepeatedString = { "string1", "string2" },
+                },
+                Child = new NestedTestAllTypes
+                {
+                    Payload = new TestAllTypes
+                    {
+                        SingleString = "single field",
+                    },
+                },
+                RepeatedChild =
+                {
+                    new NestedTestAllTypes { Payload = new TestAllTypes { SingleString = "child 1", RepeatedString = { "string" } } },
+                    new NestedTestAllTypes { Payload = new TestAllTypes { SingleString = "child 2" } },
+                },
+            };
+
+            const string expectedJson = @"
+{
+  'child': {
+    'payload': {
+      'singleString': 'single field'
+    }
+  },
+  'payload': {
+    'singleInt32': 100,
+    'singleBool': true,
+    'singleString': 'multiple fields',
+    'repeatedString': [
+      'string1',
+      'string2'
+    ]
+  },
+  'repeatedChild': [
+    {
+      'payload': {
+        'singleString': 'child 1',
+        'repeatedString': [
+          'string'
+        ]
+      }
+    },
+    {
+      'payload': {
+        'singleString': 'child 2'
+      }
+    }
+  ]
+}";
+            AssertWriteValue(value, expectedJson, JsonFormatter.Settings.Default.WithIndentation());
+        }
+
+        [Test]
+        public void WriteValueWithIndentation_WellKnownTypes()
+        {
+            var value = new TestWellKnownTypes
+            {
+                StructField = new Struct
+                {
+                    Fields =
+                    {
+                        { "string", Value.ForString("foo") },
+                        { "numbers", Value.ForList(Value.ForNumber(1), Value.ForNumber(2), Value.ForNumber(3)) },
+                        { "emptyList", Value.ForList() },
+                        { "emptyStruct", Value.ForStruct(new Struct()) },
+                    },
+                },
+            };
+
+            const string expectedJson = @"
+{
+  'structField': {
+    'string': 'foo',
+    'numbers': [
+      1,
+      2,
+      3
+    ],
+    'emptyList': [],
+    'emptyStruct': {}
+  }
+}";
+            AssertWriteValue(value, expectedJson, JsonFormatter.Settings.Default.WithIndentation());
+        }
+
+        [Test]
+        public void WriteValueWithIndentation_StructSingleField()
+        {
+            var value = new Struct { Fields = { { "structField1", Value.ForString("structFieldValue1") } } };
+
+            const string expectedJson = @"
+{
+  'structField1': 'structFieldValue1'
+}";
+            AssertWriteValue(value, expectedJson, JsonFormatter.Settings.Default.WithIndentation());
+        }
+
+        [Test]
+        public void WriteValueWithIndentation_StructMultipleFields()
+        {
+            var value = new Struct
+            {
+                Fields =
+                {
+                    { "structField1", Value.ForString("structFieldValue1") },
+                    { "structField2", Value.ForString("structFieldValue2") },
+                    { "structField3", Value.ForString("structFieldValue3") },
+                },
+            };
+
+            const string expectedJson = @"
+{
+  'structField1': 'structFieldValue1',
+  'structField2': 'structFieldValue2',
+  'structField3': 'structFieldValue3'
+}";
+            AssertWriteValue(value, expectedJson, JsonFormatter.Settings.Default.WithIndentation());
+        }
+
+        [Test]
+        public void FormatWithIndentation_EmbeddedMessage()
+        {
+            var value = new TestAllTypes { SingleInt32 = 100, SingleInt64 = 3210987654321L };
+            var formatter = new JsonFormatter(JsonFormatter.Settings.Default.WithIndentation());
+            var valueJson = formatter.Format(value, indentationLevel: 1);
+
+            var actualJson = $@"
+{{
+  ""data"": {valueJson}
+}}";
+            const string expectedJson = @"
+{
+  'data': {
+    'singleInt32': 100,
+    'singleInt64': '3210987654321'
+  }
+}";
+            AssertJson(expectedJson, actualJson.Trim());
+        }
+
+        [Test]
+        public void WriteValueWithIndentation_Map()
+        {
+            var value = new TestMap
+            {
+                MapStringString =
+                {
+                    { "key1", "value1" },
+                    { "key2", "value2" },
+                },
+            };
+
+            const string expectedJson = @"
+{
+  'mapStringString': {
+    'key1': 'value1',
+    'key2': 'value2'
+  }
+}";
+
+            AssertWriteValue(value, expectedJson, JsonFormatter.Settings.Default.WithIndentation());
+        }
+
+        [Test]
+        public void WriteValueWithIndentation_List()
+        {
+            var value = new RepeatedField<int> { 1, 2, 3 };
+            AssertWriteValue(value, "[\n  1,\n  2,\n  3\n]", JsonFormatter.Settings.Default.WithIndentation());
+        }
+
+        [Test]
+        public void WriteValueWithIndentation_CustomIndentation()
+        {
+            var value = new RepeatedField<int> { 1, 2, 3 };
+            AssertWriteValue(value, "[\n\t1,\n\t2,\n\t3\n]", JsonFormatter.Settings.Default.WithIndentation("\t"));
+        }
+
+        [Test]
+        public void Proto2_DefaultValuesWritten()
+        {
+            var value = new ProtobufTestMessages.Proto2.TestAllTypesProto2() { FieldName13 = 0 };
+            AssertWriteValue(value, "{ 'FieldName13': 0 }");
+        }
+
+        private static void AssertWriteValue(object value, string expectedJson, JsonFormatter.Settings settings = null)
+        {
+            var writer = new StringWriter { NewLine = "\n" };
+            new JsonFormatter(settings ?? JsonFormatter.Settings.Default).WriteValue(writer, value);
+            string actual = writer.ToString();
+            AssertJson(expectedJson, actual);
+        }
+
+        /// <summary>
+        /// Checks that the actual JSON is the same as the expected JSON - but after replacing
+        /// all apostrophes in the expected JSON with double quotes, trimming leading whitespace and normalizing new lines.
+        /// This basically makes the tests easier to read.
+        /// </summary>
+        /// <remarks>
+        /// Line endings are normalized because indented JSON strings are generated with system-specific line endings,
+        /// while line endings in the test cases are hard-coded, but may be converted during source checkout, depending
+        /// on git settings, causing unpredictability in the test results otherwise.</remarks>
+        private static void AssertJson(string expectedJsonWithApostrophes, string actualJson)
+        {
+            var expectedJson = expectedJsonWithApostrophes.Replace("'", "\"").Replace("\r\n", "\n").TrimStart();
+            Assert.AreEqual(expectedJson, actualJson.Replace("\r\n", "\n"));
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/JsonTokenizerTest.cs

@@ -0,0 +1,425 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using NUnit.Framework;
+using System;
+using System.IO;
+
+namespace Google.Protobuf
+{
+    public class JsonTokenizerTest
+    {
+        [Test]
+        public void EmptyObjectValue()
+        {
+            AssertTokens("{}", JsonToken.StartObject, JsonToken.EndObject);
+        }
+
+        [Test]
+        public void EmptyArrayValue()
+        {
+            AssertTokens("[]", JsonToken.StartArray, JsonToken.EndArray);
+        }
+
+        [Test]
+        [TestCase("foo", "foo")]
+        [TestCase("tab\\t", "tab\t")]
+        [TestCase("line\\nfeed", "line\nfeed")]
+        [TestCase("carriage\\rreturn", "carriage\rreturn")]
+        [TestCase("back\\bspace", "back\bspace")]
+        [TestCase("form\\ffeed", "form\ffeed")]
+        [TestCase("escaped\\/slash", "escaped/slash")]
+        [TestCase("escaped\\\\backslash", "escaped\\backslash")]
+        [TestCase("escaped\\\"quote", "escaped\"quote")]
+        [TestCase("foo {}[] bar", "foo {}[] bar")]
+        [TestCase("foo\\u09aFbar", "foo\u09afbar")] // Digits, upper hex, lower hex
+        [TestCase("ab\ud800\udc00cd", "ab\ud800\udc00cd")]
+        [TestCase("ab\\ud800\\udc00cd", "ab\ud800\udc00cd")]
+        public void StringValue(string json, string expectedValue)
+        {
+            AssertTokensNoReplacement("\"" + json + "\"", JsonToken.Value(expectedValue));
+        }
+
+        // Valid surrogate pairs, with mixed escaping. These test cases can't be expressed
+        // using TestCase as they have no valid UTF-8 representation.
+        // It's unclear exactly how we should handle a mixture of escaped or not: that can't
+        // come from UTF-8 text, but could come from a .NET string. For the moment,
+        // treat it as valid in the obvious way.
+        [Test]
+        public void MixedSurrogatePairs()
+        {
+            string expected = "\ud800\udc00";
+            AssertTokens("'\\ud800\udc00'", JsonToken.Value(expected));
+            AssertTokens("'\ud800\\udc00'", JsonToken.Value(expected));
+        }
+
+        [Test]
+        public void ObjectDepth()
+        {
+            string json = "{ \"foo\": { \"x\": 1, \"y\": [ 0 ] } }";
+            var tokenizer = JsonTokenizer.FromTextReader(new StringReader(json));
+            // If we had more tests like this, I'd introduce a helper method... but for one test, it's not worth it.
+            Assert.AreEqual(0, tokenizer.ObjectDepth);
+            Assert.AreEqual(JsonToken.StartObject, tokenizer.Next());
+            Assert.AreEqual(1, tokenizer.ObjectDepth);
+            Assert.AreEqual(JsonToken.Name("foo"), tokenizer.Next());
+            Assert.AreEqual(1, tokenizer.ObjectDepth);
+            Assert.AreEqual(JsonToken.StartObject, tokenizer.Next());
+            Assert.AreEqual(2, tokenizer.ObjectDepth);
+            Assert.AreEqual(JsonToken.Name("x"), tokenizer.Next());
+            Assert.AreEqual(2, tokenizer.ObjectDepth);
+            Assert.AreEqual(JsonToken.Value(1), tokenizer.Next());
+            Assert.AreEqual(2, tokenizer.ObjectDepth);
+            Assert.AreEqual(JsonToken.Name("y"), tokenizer.Next());
+            Assert.AreEqual(2, tokenizer.ObjectDepth);
+            Assert.AreEqual(JsonToken.StartArray, tokenizer.Next());
+            Assert.AreEqual(2, tokenizer.ObjectDepth); // Depth hasn't changed in array
+            Assert.AreEqual(JsonToken.Value(0), tokenizer.Next());
+            Assert.AreEqual(2, tokenizer.ObjectDepth);
+            Assert.AreEqual(JsonToken.EndArray, tokenizer.Next());
+            Assert.AreEqual(2, tokenizer.ObjectDepth);
+            Assert.AreEqual(JsonToken.EndObject, tokenizer.Next());
+            Assert.AreEqual(1, tokenizer.ObjectDepth);
+            Assert.AreEqual(JsonToken.EndObject, tokenizer.Next());
+            Assert.AreEqual(0, tokenizer.ObjectDepth);
+            Assert.AreEqual(JsonToken.EndDocument, tokenizer.Next());
+            Assert.AreEqual(0, tokenizer.ObjectDepth);
+        }
+
+        [Test]
+        public void ObjectDepth_WithPushBack()
+        {
+            string json = "{}";
+            var tokenizer = JsonTokenizer.FromTextReader(new StringReader(json));
+            Assert.AreEqual(0, tokenizer.ObjectDepth);
+            var token = tokenizer.Next();
+            Assert.AreEqual(1, tokenizer.ObjectDepth);
+            // When we push back a "start object", we should effectively be back to the previous depth.
+            tokenizer.PushBack(token);
+            Assert.AreEqual(0, tokenizer.ObjectDepth);
+            // Read the same token again, and get back to depth 1
+            _ = tokenizer.Next();
+            Assert.AreEqual(1, tokenizer.ObjectDepth);
+
+            // Now the same in reverse, with EndObject
+            token = tokenizer.Next();
+            Assert.AreEqual(0, tokenizer.ObjectDepth);
+            tokenizer.PushBack(token);
+            Assert.AreEqual(1, tokenizer.ObjectDepth);
+            tokenizer.Next();
+            Assert.AreEqual(0, tokenizer.ObjectDepth);
+        }
+
+        [Test]
+        [TestCase("embedded tab\t")]
+        [TestCase("embedded CR\r")]
+        [TestCase("embedded LF\n")]
+        [TestCase("embedded bell\u0007")]
+        [TestCase("bad escape\\a")]
+        [TestCase("incomplete escape\\")]
+        [TestCase("incomplete Unicode escape\\u000")]
+        [TestCase("invalid Unicode escape\\u000H")]
+        // Surrogate pair handling, both in raw .NET strings and escaped. We only need
+        // to detect this in strings, as non-ASCII characters anywhere other than in strings
+        // will already lead to parsing errors.
+        [TestCase("\\ud800")]
+        [TestCase("\\udc00")]
+        [TestCase("\\ud800x")]
+        [TestCase("\\udc00x")]
+        [TestCase("\\udc00\\ud800y")]
+        public void InvalidStringValue(string json)
+        {
+            AssertThrowsAfter("\"" + json + "\"");
+        }
+
+        // Tests for invalid strings that can't be expressed in attributes,
+        // as the constants can't be expressed as UTF-8 strings.
+        [Test]
+        public void InvalidSurrogatePairs()
+        {
+            AssertThrowsAfter("\"\ud800x\"");
+            AssertThrowsAfter("\"\udc00y\"");
+            AssertThrowsAfter("\"\udc00\ud800y\"");
+        }
+
+        [Test]
+        [TestCase("0", 0)]
+        [TestCase("-0", 0)] // We don't distinguish between positive and negative 0
+        [TestCase("1", 1)]
+        [TestCase("-1", -1)]
+        // From here on, assume leading sign is okay...
+        [TestCase("1.125", 1.125)]
+        [TestCase("1.0", 1)]
+        [TestCase("1e5", 100000)]
+        [TestCase("1e000000", 1)] // Weird, but not prohibited by the spec
+        [TestCase("1E5", 100000)]
+        [TestCase("1e+5", 100000)]
+        [TestCase("1E-5", 0.00001)]
+        [TestCase("123E-2", 1.23)]
+        [TestCase("123.45E3", 123450)]
+        [TestCase("   1   ", 1)]
+        public void NumberValue(string json, double expectedValue)
+        {
+            AssertTokens(json, JsonToken.Value(expectedValue));
+        }
+
+        [Test]
+        [TestCase("00")]
+        [TestCase(".5")]
+        [TestCase("1.")]
+        [TestCase("1e")]
+        [TestCase("1e-")]
+        [TestCase("--")]
+        [TestCase("--1")]
+        [TestCase("-1.7977e308")]
+        [TestCase("1.7977e308")]
+        public void InvalidNumberValue(string json)
+        {
+            AssertThrowsAfter(json);
+        }
+
+        [Test]
+        [TestCase("nul")]
+        [TestCase("nothing")]
+        [TestCase("truth")]
+        [TestCase("fALSEhood")]
+        public void InvalidLiterals(string json)
+        {
+            AssertThrowsAfter(json);
+        }
+
+        [Test]
+        public void NullValue()
+        {
+            AssertTokens("null", JsonToken.Null);
+        }
+
+        [Test]
+        public void TrueValue()
+        {
+            AssertTokens("true", JsonToken.True);
+        }
+
+        [Test]
+        public void FalseValue()
+        {
+            AssertTokens("false", JsonToken.False);
+        }
+
+        [Test]
+        public void SimpleObject()
+        {
+            AssertTokens("{'x': 'y'}",
+                JsonToken.StartObject, JsonToken.Name("x"), JsonToken.Value("y"), JsonToken.EndObject);
+        }
+
+        [Test]
+        [TestCase("[10, 20", 3)]
+        [TestCase("[10,", 2)]
+        [TestCase("[10:20]", 2)]
+        [TestCase("[", 1)]
+        [TestCase("[,", 1)]
+        [TestCase("{", 1)]
+        [TestCase("{,", 1)]
+        [TestCase("{[", 1)]
+        [TestCase("{{", 1)]
+        [TestCase("{0", 1)]
+        [TestCase("{null", 1)]
+        [TestCase("{false", 1)]
+        [TestCase("{true", 1)]
+        [TestCase("}", 0)]
+        [TestCase("]", 0)]
+        [TestCase(",", 0)]
+        [TestCase("'foo' 'bar'", 1)]
+        [TestCase(":", 0)]
+        [TestCase("'foo", 0)] // Incomplete string
+        [TestCase("{ 'foo' }", 2)]
+        [TestCase("{ x:1", 1)] // Property names must be quoted
+        [TestCase("{]", 1)]
+        [TestCase("[}", 1)]
+        [TestCase("[1,", 2)]
+        [TestCase("{'x':0]", 3)]
+        [TestCase("{ 'foo': }", 2)]
+        [TestCase("{ 'foo':'bar', }", 3)]
+        public void InvalidStructure(string json, int expectedValidTokens)
+        {
+            // Note: we don't test that the earlier tokens are exactly as expected,
+            // partly because that's hard to parameterize.
+            var reader = new StringReader(json.Replace('\'', '"'));
+            var tokenizer = JsonTokenizer.FromTextReader(reader);
+            for (int i = 0; i < expectedValidTokens; i++)
+            {
+                Assert.IsNotNull(tokenizer.Next());
+            }
+            Assert.Throws<InvalidJsonException>(() => tokenizer.Next());
+        }
+
+        [Test]
+        public void ArrayMixedType()
+        {
+            AssertTokens("[1, 'foo', null, false, true, [2], {'x':'y' }]",
+                JsonToken.StartArray,
+                JsonToken.Value(1),
+                JsonToken.Value("foo"),
+                JsonToken.Null,
+                JsonToken.False,
+                JsonToken.True,
+                JsonToken.StartArray,
+                JsonToken.Value(2),
+                JsonToken.EndArray,
+                JsonToken.StartObject,
+                JsonToken.Name("x"),
+                JsonToken.Value("y"),
+                JsonToken.EndObject,
+                JsonToken.EndArray);
+        }
+
+        [Test]
+        public void ObjectMixedType()
+        {
+            AssertTokens(@"{'a': 1, 'b': 'bar', 'c': null, 'd': false, 'e': true,
+                           'f': [2], 'g': {'x':'y' }}",
+                JsonToken.StartObject,
+                JsonToken.Name("a"),
+                JsonToken.Value(1),
+                JsonToken.Name("b"),
+                JsonToken.Value("bar"),
+                JsonToken.Name("c"),
+                JsonToken.Null,
+                JsonToken.Name("d"),
+                JsonToken.False,
+                JsonToken.Name("e"),
+                JsonToken.True,
+                JsonToken.Name("f"),
+                JsonToken.StartArray,
+                JsonToken.Value(2),
+                JsonToken.EndArray,
+                JsonToken.Name("g"),
+                JsonToken.StartObject,
+                JsonToken.Name("x"),
+                JsonToken.Value("y"),
+                JsonToken.EndObject,
+                JsonToken.EndObject);
+        }
+
+        [Test]
+        public void NextAfterEndDocumentThrows()
+        {
+            var tokenizer = JsonTokenizer.FromTextReader(new StringReader("null"));
+            Assert.AreEqual(JsonToken.Null, tokenizer.Next());
+            Assert.AreEqual(JsonToken.EndDocument, tokenizer.Next());
+            Assert.Throws<InvalidOperationException>(() => tokenizer.Next());
+        }
+
+        [Test]
+        public void CanPushBackEndDocument()
+        {
+            var tokenizer = JsonTokenizer.FromTextReader(new StringReader("null"));
+            Assert.AreEqual(JsonToken.Null, tokenizer.Next());
+            Assert.AreEqual(JsonToken.EndDocument, tokenizer.Next());
+            tokenizer.PushBack(JsonToken.EndDocument);
+            Assert.AreEqual(JsonToken.EndDocument, tokenizer.Next());
+            Assert.Throws<InvalidOperationException>(() => tokenizer.Next());
+        }
+
+        [Test]
+        [TestCase("{ 'skip': 0, 'next': 1")]
+        [TestCase("{ 'skip': [0, 1, 2], 'next': 1")]
+        [TestCase("{ 'skip': 'x', 'next': 1")]
+        [TestCase("{ 'skip': ['x', 'y'], 'next': 1")]
+        [TestCase("{ 'skip': {'a': 0}, 'next': 1")]
+        [TestCase("{ 'skip': {'a': [0, {'b':[]}]}, 'next': 1")]
+        public void SkipValue(string json)
+        {
+            var tokenizer = JsonTokenizer.FromTextReader(new StringReader(json.Replace('\'', '"')));
+            Assert.AreEqual(JsonToken.StartObject, tokenizer.Next());
+            Assert.AreEqual("skip", tokenizer.Next().StringValue);
+            tokenizer.SkipValue();
+            Assert.AreEqual("next", tokenizer.Next().StringValue);
+        }
+
+        /// <summary>
+        /// Asserts that the specified JSON is tokenized into the given sequence of tokens.
+        /// All apostrophes are first converted to double quotes, allowing any tests
+        /// that don't need to check actual apostrophe handling to use apostrophes in the JSON, avoiding
+        /// messy string literal escaping. The "end document" token is not specified in the list of
+        /// expected tokens, but is implicit.
+        /// </summary>
+        private static void AssertTokens(string json, params JsonToken[] expectedTokens)
+        {
+            AssertTokensNoReplacement(json.Replace('\'', '"'), expectedTokens);
+        }
+
+        /// <summary>
+        /// Asserts that the specified JSON is tokenized into the given sequence of tokens.
+        /// Unlike <see cref="AssertTokens(string, JsonToken[])"/>, this does not perform any character
+        /// replacement on the specified JSON, and should be used when the text contains apostrophes which
+        /// are expected to be used *as* apostrophes. The "end document" token is not specified in the list of
+        /// expected tokens, but is implicit.
+        /// </summary>
+        private static void AssertTokensNoReplacement(string json, params JsonToken[] expectedTokens)
+        {
+            var reader = new StringReader(json);
+            var tokenizer = JsonTokenizer.FromTextReader(reader);
+            for (int i = 0; i < expectedTokens.Length; i++)
+            {
+                var actualToken = tokenizer.Next();
+                if (actualToken == JsonToken.EndDocument)
+                {
+                    Assert.Fail("Expected {0} but reached end of token stream", expectedTokens[i]);
+                }
+                Assert.AreEqual(expectedTokens[i], actualToken);
+            }
+            var finalToken = tokenizer.Next();
+            if (finalToken != JsonToken.EndDocument)
+            {
+                Assert.Fail("Expected token stream to be exhausted; received {0}", finalToken);
+            }
+        }
+
+        private static void AssertThrowsAfter(string json, params JsonToken[] expectedTokens)
+        {
+            var reader = new StringReader(json);
+            var tokenizer = JsonTokenizer.FromTextReader(reader);
+            for (int i = 0; i < expectedTokens.Length; i++)
+            {
+                var actualToken = tokenizer.Next();
+                if (actualToken == JsonToken.EndDocument)
+                {
+                    Assert.Fail("Expected {0} but reached end of document", expectedTokens[i]);
+                }
+                Assert.AreEqual(expectedTokens[i], actualToken);
+            }
+            Assert.Throws<InvalidJsonException>(() => tokenizer.Next());
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/LegacyGeneratedCodeTest.cs

@@ -0,0 +1,294 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System.Buffers;
+using pb = Google.Protobuf;
+using pbr = Google.Protobuf.Reflection;
+using NUnit.Framework;
+using System.IO;
+using Google.Protobuf.Buffers;
+
+namespace Google.Protobuf
+{
+    public class LegacyGeneratedCodeTest
+    {
+        [Test]
+        public void IntermixingOfNewAndLegacyGeneratedCodeWorksWithCodedInputStream()
+        {
+            var message = new ParseContextEnabledMessageB
+            {
+                A = new LegacyGeneratedCodeMessageA
+                {
+                    Bb = new ParseContextEnabledMessageB { OptionalInt32 = 12345 }
+                },
+                OptionalInt32 = 6789
+            };
+            var data = message.ToByteArray();
+
+            // when parsing started using CodedInputStream and a message with legacy generated code
+            // is encountered somewhere in the parse tree, we still need to be able to use its
+            // MergeFrom(CodedInputStream) method to parse correctly.
+            var codedInput = new CodedInputStream(data);
+            var parsed = new ParseContextEnabledMessageB();
+            codedInput.ReadRawMessage(parsed);
+            Assert.IsTrue(codedInput.IsAtEnd);
+
+            Assert.AreEqual(12345, parsed.A.Bb.OptionalInt32);
+            Assert.AreEqual(6789, parsed.OptionalInt32);
+        }
+
+        [Test]
+        public void LegacyGeneratedCodeThrowsWithReadOnlySequence()
+        {
+            var message = new ParseContextEnabledMessageB
+            {
+                A = new LegacyGeneratedCodeMessageA
+                {
+                    Bb = new ParseContextEnabledMessageB { OptionalInt32 = 12345 }
+                },
+                OptionalInt32 = 6789
+            };
+            var data = message.ToByteArray();
+
+            // if parsing started using ReadOnlySequence and we don't have a CodedInputStream
+            // instance at hand, we cannot fall back to the legacy MergeFrom(CodedInputStream)
+            // method and parsing will fail. As a consequence, one can only use parsing
+            // from ReadOnlySequence if all the messages in the parsing tree have their generated
+            // code up to date.
+            var exception = Assert.Throws<InvalidProtocolBufferException>(() =>
+            {
+                ParseContext.Initialize(new ReadOnlySequence<byte>(data), out ParseContext parseCtx);
+                var parsed = new ParseContextEnabledMessageB();
+                ParsingPrimitivesMessages.ReadRawMessage(ref parseCtx, parsed);
+            });
+            Assert.AreEqual($"Message {typeof(LegacyGeneratedCodeMessageA).Name} doesn't provide the generated method that enables ParseContext-based parsing. You might need to regenerate the generated protobuf code.", exception.Message);
+        }
+
+        [Test]
+        public void IntermixingOfNewAndLegacyGeneratedCodeWorksWithCodedOutputStream()
+        {
+            // when serialization started using CodedOutputStream and a message with legacy generated code
+            // is encountered somewhere in the parse tree, we still need to be able to use its
+            // WriteTo(CodedOutputStream) method to serialize correctly.
+            var ms = new MemoryStream();
+            var codedOutput = new CodedOutputStream(ms);
+            var message = new ParseContextEnabledMessageB
+            {
+                A = new LegacyGeneratedCodeMessageA
+                {
+                    Bb = new ParseContextEnabledMessageB { OptionalInt32 = 12345 }
+                },
+                OptionalInt32 = 6789
+            };
+            message.WriteTo(codedOutput);
+            codedOutput.Flush();
+
+            var codedInput = new CodedInputStream(ms.ToArray());
+            var parsed = new ParseContextEnabledMessageB();
+            codedInput.ReadRawMessage(parsed);
+            Assert.IsTrue(codedInput.IsAtEnd);
+
+            Assert.AreEqual(12345, parsed.A.Bb.OptionalInt32);
+            Assert.AreEqual(6789, parsed.OptionalInt32);
+        }
+
+        [Test]
+        public void LegacyGeneratedCodeThrowsWithIBufferWriter()
+        {
+            // if serialization started using IBufferWriter and we don't have a CodedOutputStream
+            // instance at hand, we cannot fall back to the legacy WriteTo(CodedOutputStream)
+            // method and serializatin will fail. As a consequence, one can only use serialization
+            // to IBufferWriter if all the messages in the parsing tree have their generated
+            // code up to date.
+            var message = new ParseContextEnabledMessageB
+            {
+                A = new LegacyGeneratedCodeMessageA
+                {
+                    Bb = new ParseContextEnabledMessageB { OptionalInt32 = 12345 }
+                },
+                OptionalInt32 = 6789
+            };
+            var exception = Assert.Throws<InvalidProtocolBufferException>(() =>
+            {
+                WriteContext.Initialize(new TestArrayBufferWriter<byte>(), out WriteContext writeCtx);
+                ((IBufferMessage)message).InternalWriteTo(ref writeCtx);
+            });
+            Assert.AreEqual($"Message {typeof(LegacyGeneratedCodeMessageA).Name} doesn't provide the generated method that enables WriteContext-based serialization. You might need to regenerate the generated protobuf code.", exception.Message);
+        }
+
+        // hand-modified version of a generated message that only provides the legacy
+        // MergeFrom(CodedInputStream) method and doesn't implement IBufferMessage.
+        private sealed partial class LegacyGeneratedCodeMessageA : pb::IMessage {
+          private pb::UnknownFieldSet _unknownFields;
+
+          pbr::MessageDescriptor pb::IMessage.Descriptor => throw new System.NotImplementedException();
+
+          /// <summary>Field number for the "bb" field.</summary>
+          public const int BbFieldNumber = 1;
+          private ParseContextEnabledMessageB bb_;
+          public ParseContextEnabledMessageB Bb {
+            get { return bb_; }
+            set {
+              bb_ = value;
+            }
+          }
+
+          public void WriteTo(pb::CodedOutputStream output) {
+            if (bb_ != null) {
+              output.WriteRawTag(10);
+              output.WriteMessage(Bb);
+            }
+            if (_unknownFields != null) {
+              _unknownFields.WriteTo(output);
+            }
+          }
+
+          public int CalculateSize() {
+            int size = 0;
+            if (bb_ != null) {
+              size += 1 + pb::CodedOutputStream.ComputeMessageSize(Bb);
+            }
+            if (_unknownFields != null) {
+              size += _unknownFields.CalculateSize();
+            }
+            return size;
+          }
+
+          public void MergeFrom(pb::CodedInputStream input) {
+            uint tag;
+            while ((tag = input.ReadTag()) != 0) {
+              switch(tag) {
+                default:
+                  _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
+                  break;
+                case 10: {
+                  if (bb_ == null) {
+                    Bb = new ParseContextEnabledMessageB();
+                  }
+                  input.ReadMessage(Bb);
+                  break;
+                }
+              }
+            }
+          }
+        }
+
+        // hand-modified version of a generated message that does provide
+        // the new InternalMergeFrom(ref ParseContext) method.
+        private sealed partial class ParseContextEnabledMessageB : pb::IBufferMessage {
+          private pb::UnknownFieldSet _unknownFields;
+
+          pbr::MessageDescriptor pb::IMessage.Descriptor => throw new System.NotImplementedException();
+
+          /// <summary>Field number for the "a" field.</summary>
+          public const int AFieldNumber = 1;
+          private LegacyGeneratedCodeMessageA a_;
+          public LegacyGeneratedCodeMessageA A {
+            get { return a_; }
+            set {
+              a_ = value;
+            }
+          }
+
+          /// <summary>Field number for the "optional_int32" field.</summary>
+          public const int OptionalInt32FieldNumber = 2;
+          private int optionalInt32_;
+          public int OptionalInt32 {
+            get { return optionalInt32_; }
+            set {
+              optionalInt32_ = value;
+            }
+          }
+
+          public void WriteTo(pb::CodedOutputStream output) {
+            output.WriteRawMessage(this);
+          }
+
+          void pb::IBufferMessage.InternalWriteTo(ref pb::WriteContext output)
+          {
+            if (a_ != null)
+            {
+              output.WriteRawTag(10);
+              output.WriteMessage(A);
+            }
+            if (OptionalInt32 != 0)
+            {
+              output.WriteRawTag(16);
+              output.WriteInt32(OptionalInt32);
+            }
+            if (_unknownFields != null)
+            {
+              _unknownFields.WriteTo(ref output);
+            }
+          }
+
+          public int CalculateSize() {
+            int size = 0;
+            if (a_ != null) {
+              size += 1 + pb::CodedOutputStream.ComputeMessageSize(A);
+            }
+            if (OptionalInt32 != 0) {
+              size += 1 + pb::CodedOutputStream.ComputeInt32Size(OptionalInt32);
+            }
+            if (_unknownFields != null) {
+              size += _unknownFields.CalculateSize();
+            }
+            return size;
+          }
+          public void MergeFrom(pb::CodedInputStream input) {
+            input.ReadRawMessage(this);
+          }
+
+          void pb::IBufferMessage.InternalMergeFrom(ref pb::ParseContext input) {
+            uint tag;
+            while ((tag = input.ReadTag()) != 0) {
+              switch(tag) {
+                default:
+                  _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, ref input);
+                  break;
+                case 10: {
+                  if (a_ == null) {
+                    A = new LegacyGeneratedCodeMessageA();
+                  }
+                  input.ReadMessage(A);
+                  break;
+                }
+                case 16: {
+                  OptionalInt32 = input.ReadInt32();
+                  break;
+                }
+              }
+            }
+          }
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/MessageParsingHelpers.cs

@@ -0,0 +1,153 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using NUnit.Framework;
+using System;
+using System.Buffers;
+using Google.Protobuf.Buffers;
+
+namespace Google.Protobuf
+{
+    public static class MessageParsingHelpers
+    {
+        public static void AssertReadingMessage<T>(MessageParser<T> parser, byte[] bytes, Action<T> assert) where T : IMessage<T>
+        {
+            var parsedMsg = parser.ParseFrom(bytes);
+            assert(parsedMsg);
+
+            // Load content as single segment
+            parsedMsg = parser.ParseFrom(new ReadOnlySequence<byte>(bytes));
+            assert(parsedMsg);
+
+            // Load content as multiple segments
+            parsedMsg = parser.ParseFrom(ReadOnlySequenceFactory.CreateWithContent(bytes));
+            assert(parsedMsg);
+
+            // Load content as ReadOnlySpan
+            parsedMsg = parser.ParseFrom(new ReadOnlySpan<byte>(bytes));
+            assert(parsedMsg);
+        }
+
+        public static void AssertReadingMessage(MessageParser parser, byte[] bytes, Action<IMessage> assert)
+        {
+            var parsedMsg = parser.ParseFrom(bytes);
+            assert(parsedMsg);
+
+            // Load content as single segment
+            parsedMsg = parser.ParseFrom(new ReadOnlySequence<byte>(bytes));
+            assert(parsedMsg);
+
+            // Load content as multiple segments
+            parsedMsg = parser.ParseFrom(ReadOnlySequenceFactory.CreateWithContent(bytes));
+            assert(parsedMsg);
+
+            // Load content as ReadOnlySpan
+            parsedMsg = parser.ParseFrom(new ReadOnlySpan<byte>(bytes));
+            assert(parsedMsg);
+        }
+
+        public static void AssertReadingMessageThrows<TMessage, TException>(MessageParser<TMessage> parser, byte[] bytes)
+            where TMessage : IMessage<TMessage>
+            where TException : Exception
+        {
+            Assert.Throws<TException>(() => parser.ParseFrom(bytes));
+
+            Assert.Throws<TException>(() => parser.ParseFrom(new ReadOnlySequence<byte>(bytes)));
+
+            Assert.Throws<TException>(() => parser.ParseFrom(new ReadOnlySpan<byte>(bytes)));
+        }
+
+        public static void AssertRoundtrip<T>(MessageParser<T> parser, T message, Action<T> additionalAssert = null) where T : IMessage<T>
+        {
+            var bytes = message.ToByteArray();
+
+            // also serialize using IBufferWriter and check it leads to the same data
+            var bufferWriter = new TestArrayBufferWriter<byte>();
+            message.WriteTo(bufferWriter);
+            Assert.AreEqual(bytes, bufferWriter.WrittenSpan.ToArray(), "Both serialization approaches need to result in the same data.");
+
+            var parsedMsg = parser.ParseFrom(bytes);
+            Assert.AreEqual(message, parsedMsg);
+            additionalAssert?.Invoke(parsedMsg);
+
+            // Load content as single segment
+            parsedMsg = parser.ParseFrom(new ReadOnlySequence<byte>(bytes));
+            Assert.AreEqual(message, parsedMsg);
+            additionalAssert?.Invoke(parsedMsg);
+
+            // Load content as multiple segments
+            parsedMsg = parser.ParseFrom(ReadOnlySequenceFactory.CreateWithContent(bytes));
+            Assert.AreEqual(message, parsedMsg);
+            additionalAssert?.Invoke(parsedMsg);
+
+            // Load content as ReadOnlySpan
+            parsedMsg = parser.ParseFrom(new ReadOnlySpan<byte>(bytes));
+            Assert.AreEqual(message, parsedMsg);
+            additionalAssert?.Invoke(parsedMsg);
+        }
+
+        public static void AssertWritingMessage(IMessage message)
+        {
+            // serialize using CodedOutputStream
+            var bytes = message.ToByteArray();
+
+            int messageSize = message.CalculateSize(); 
+            Assert.AreEqual(message.CalculateSize(), bytes.Length);
+
+            // serialize using IBufferWriter and check it leads to the same output
+            var bufferWriter = new TestArrayBufferWriter<byte>();
+            message.WriteTo(bufferWriter);
+            Assert.AreEqual(bytes, bufferWriter.WrittenSpan.ToArray());
+
+            // serialize into a single span and check it leads to the same output
+            var singleSpan = new Span<byte>(new byte[messageSize]);
+            message.WriteTo(singleSpan);
+            Assert.AreEqual(bytes, singleSpan.ToArray());
+
+            // test for different IBufferWriter.GetSpan() segment sizes
+            for (int blockSize = 1; blockSize < 256; blockSize *= 2)
+            {
+                var segmentedBufferWriter = new TestArrayBufferWriter<byte> { MaxGrowBy = blockSize };
+                message.WriteTo(segmentedBufferWriter);
+                Assert.AreEqual(bytes, segmentedBufferWriter.WrittenSpan.ToArray());
+            }
+
+            // if the full message is small enough, try serializing directly into stack-allocated buffer
+            if (bytes.Length <= 256)
+            {
+                Span<byte> stackAllocBuffer = stackalloc byte[bytes.Length];
+                message.WriteTo(stackAllocBuffer);
+                Assert.AreEqual(bytes, stackAllocBuffer.ToArray());
+            }
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/ParsingPrimitivesTest.cs

@@ -0,0 +1,63 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2022 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using NUnit.Framework;
+using System;
+using System.Linq;
+
+namespace Google.Protobuf.Test;
+
+internal class ParsingPrimitivesTest
+{
+    // Note: test cases use integers rather than bytes as they're easier
+    // to specify in attributes.
+
+    [Test]
+    [TestCase("\ufffd", 255)]
+    [TestCase("A\ufffd", 65, 255)]
+    [TestCase("A\ufffd\ufffdB", 65, 255, 255, 66)]
+    // Overlong form of "space"
+    [TestCase("\ufffd\ufffd", 0xc0, 0xa0)]
+    public void ReadRawString_NonUtf8(string expectedText, params int[] bytes)
+    {
+        var context = CreateContext(bytes);
+        string text = ParsingPrimitives.ReadRawString(ref context.buffer, ref context.state, bytes.Length);
+        Assert.AreEqual(expectedText, text);
+    }
+
+    private static ParseContext CreateContext(int[] bytes)
+    {
+        byte[] actualBytes = bytes.Select(b => (byte) b).ToArray();
+        ParseContext.Initialize(actualBytes.AsSpan(), out var context);
+        return context;
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/Proto3OptionalTest.cs

@@ -0,0 +1,153 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using NUnit.Framework;
+using ProtobufUnittest;
+using System;
+using System.IO;
+using UnitTest.Issues.TestProtos;
+
+namespace Google.Protobuf.Test
+{
+    public class Proto3OptionalTest
+    {
+        [Test]
+        public void OptionalInt32FieldLifecycle()
+        {
+            var message = new TestProto3Optional();
+            Assert.IsFalse(message.HasOptionalInt32);
+            Assert.AreEqual(0, message.OptionalInt32);
+
+            message.OptionalInt32 = 5;
+            Assert.IsTrue(message.HasOptionalInt32);
+            Assert.AreEqual(5, message.OptionalInt32);
+
+            message.OptionalInt32 = 0;
+            Assert.IsTrue(message.HasOptionalInt32);
+            Assert.AreEqual(0, message.OptionalInt32);
+
+            message.ClearOptionalInt32();
+            Assert.IsFalse(message.HasOptionalInt32);
+            Assert.AreEqual(0, message.OptionalInt32);
+        }
+
+        [Test]
+        public void OptionalStringFieldLifecycle()
+        {
+            var message = new TestProto3Optional();
+            Assert.IsFalse(message.HasOptionalString);
+            Assert.AreEqual("", message.OptionalString);
+
+            message.OptionalString = "x";
+            Assert.IsTrue(message.HasOptionalString);
+            Assert.AreEqual("x", message.OptionalString);
+
+            message.OptionalString = "";
+            Assert.IsTrue(message.HasOptionalString);
+            Assert.AreEqual("", message.OptionalString);
+
+            message.ClearOptionalString();
+            Assert.IsFalse(message.HasOptionalString);
+            Assert.AreEqual("", message.OptionalString);
+
+            Assert.Throws<ArgumentNullException>(() => message.OptionalString = null);
+        }
+
+        [Test]
+        public void Clone()
+        {
+            var original = new TestProto3Optional { OptionalInt64 = 0L };
+
+            var clone = original.Clone();
+            Assert.False(clone.HasOptionalInt32);
+            Assert.AreEqual(0, clone.OptionalInt32);
+            Assert.True(clone.HasOptionalInt64);
+            Assert.AreEqual(0L, clone.OptionalInt64);
+        }
+
+        [Test]
+        public void Serialization_NotSet()
+        {
+            var stream = new MemoryStream();
+            var message = new TestProto3Optional();
+            message.WriteTo(stream);
+            Assert.AreEqual(0, stream.Length);
+        }
+
+        [Test]
+        public void Serialization_SetToDefault()
+        {
+            var stream = new MemoryStream();
+            var message = new TestProto3Optional { OptionalInt32 = 0 };
+            message.WriteTo(stream);
+            Assert.AreEqual(2, stream.Length); // Tag and value
+        }
+
+        [Test]
+        public void Serialization_Roundtrip()
+        {
+            var original = new TestProto3Optional { OptionalInt64 = 0L, OptionalFixed32 = 5U };
+            var stream = new MemoryStream();
+            original.WriteTo(stream);
+            stream.Position = 0;
+            var deserialized = TestProto3Optional.Parser.ParseFrom(stream);
+
+            Assert.AreEqual(0, deserialized.OptionalInt32);
+            Assert.IsFalse(deserialized.HasOptionalInt32);
+
+            Assert.AreEqual(0L, deserialized.OptionalInt64);
+            Assert.IsTrue(deserialized.HasOptionalInt64);
+
+            Assert.AreEqual(5U, deserialized.OptionalFixed32);
+            Assert.IsTrue(deserialized.HasOptionalFixed32);
+        }
+
+        [Test]
+        public void Equality_IgnoresPresence()
+        {
+            var message1 = new TestProto3Optional { OptionalInt32 = 0 };
+            var message2 = new TestProto3Optional();
+
+            Assert.IsTrue(message1.Equals(message2));
+            message1.ClearOptionalInt32();
+        }
+
+        [Test]
+        public void MixedFields()
+        {
+            var descriptor = MixedRegularAndOptional.Descriptor;
+            Assert.AreEqual(1, descriptor.Oneofs.Count);
+            Assert.AreEqual(0, descriptor.RealOneofCount);
+            Assert.True(descriptor.Oneofs[0].IsSynthetic);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/ReadOnlySequenceFactory.cs

@@ -0,0 +1,136 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.Buffers;
+using System.Collections.Generic;
+
+namespace Google.Protobuf
+{
+    internal static class ReadOnlySequenceFactory
+    {
+        /// <summary>
+        /// Create a sequence from the specified data. The data will be divided up into segments in the sequence.
+        /// </summary>
+        public static ReadOnlySequence<byte> CreateWithContent(byte[] data, int segmentSize = 1, bool addEmptySegmentDelimiters = true)
+        {
+            var segments = new List<byte[]>();
+
+            if (addEmptySegmentDelimiters)
+            {
+                segments.Add(Array.Empty<byte>());
+            }
+
+            var currentIndex = 0;
+            while (currentIndex < data.Length)
+            {
+                var segment = new List<byte>();
+                while (segment.Count < segmentSize && currentIndex < data.Length)
+                {
+                    segment.Add(data[currentIndex++]);
+                }
+                segments.Add(segment.ToArray());
+
+                if (addEmptySegmentDelimiters)
+                {
+                    segments.Add(Array.Empty<byte>());
+                }
+            }
+
+            return CreateSegments(segments.ToArray());
+        }
+
+        /// <summary>
+        /// Originally from corefx, and has been contributed to Protobuf
+        /// https://github.com/dotnet/corefx/blob/e99ec129cfd594d53f4390bf97d1d736cff6f860/src/System.Memory/tests/ReadOnlyBuffer/ReadOnlySequenceFactory.byte.cs
+        /// </summary>
+        private static ReadOnlySequence<byte> CreateSegments(params byte[][] inputs)
+        {
+            if (inputs == null || inputs.Length == 0)
+            {
+                throw new InvalidOperationException();
+            }
+
+            int i = 0;
+
+            BufferSegment last = null;
+            BufferSegment first = null;
+
+            do
+            {
+                byte[] s = inputs[i];
+                int length = s.Length;
+                int dataOffset = length;
+                var chars = new byte[length * 2];
+
+                for (int j = 0; j < length; j++)
+                {
+                    chars[dataOffset + j] = s[j];
+                }
+
+                // Create a segment that has offset relative to the OwnedMemory and OwnedMemory itself has offset relative to array
+                var memory = new Memory<byte>(chars).Slice(length, length);
+
+                if (first == null)
+                {
+                    first = new BufferSegment(memory);
+                    last = first;
+                }
+                else
+                {
+                    last = last.Append(memory);
+                }
+                i++;
+            } while (i < inputs.Length);
+
+            return new ReadOnlySequence<byte>(first, 0, last, last.Memory.Length);
+        }
+
+        private class BufferSegment : ReadOnlySequenceSegment<byte>
+        {
+            public BufferSegment(Memory<byte> memory)
+            {
+                Memory = memory;
+            }
+
+            public BufferSegment Append(Memory<byte> memory)
+            {
+                var segment = new BufferSegment(memory)
+                {
+                    RunningIndex = RunningIndex + Memory.Length
+                };
+                Next = segment;
+                return segment;
+            }
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/RefStructCompatibilityTest.cs

@@ -0,0 +1,118 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using NUnit.Framework;
+using System.Diagnostics;
+using System;
+using System.Reflection;
+using System.IO;
+
+namespace Google.Protobuf
+{
+    public class RefStructCompatibilityTest
+    {
+        /// <summary>
+        /// Checks that the generated code can be compiler with an old C# compiler.
+        /// The reason why this test is needed is that even though dotnet SDK projects allow to set LangVersion,
+        /// this setting doesn't accurately simulate compilation with an actual old pre-roslyn C# compiler.
+        /// For instance, the "ref struct" types are only supported by C# 7.2 and higher, but even if
+        /// LangVersion is set low, the roslyn compiler still understands the concept of ref struct
+        /// and silently accepts them. Therefore we try to build the generated code with an actual old C# compiler
+        /// to be able to catch these sort of compatibility problems.
+        /// </summary>
+        [Test]
+        public void GeneratedCodeCompilesWithOldCsharpCompiler()
+        {
+            if (Environment.OSVersion.Platform != PlatformID.Win32NT)
+            {
+                // This tests needs old C# compiler which is only available on Windows. Skipping it on all other platforms.
+                return;
+            }
+
+            var currentAssemblyDir = Path.GetDirectoryName(typeof(RefStructCompatibilityTest).GetTypeInfo().Assembly.Location);
+            var testProtosProjectDir = Path.GetFullPath(Path.Combine(currentAssemblyDir, "..", "..", "..", "..", "Google.Protobuf.Test.TestProtos"));
+            var testProtosOutputDir = (currentAssemblyDir.Contains("bin/Debug/") || currentAssemblyDir.Contains("bin\\Debug\\")) ? "bin\\Debug\\net462" : "bin\\Release\\net462";
+
+            // If "ref struct" types are used in the generated code, compilation with an old compiler will fail with the following error:
+            // "XYZ is obsolete: 'Types with embedded references are not supported in this version of your compiler.'"
+            // We build the code with GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE to avoid the use of ref struct in the generated code.
+            var compatibilityFlag = "-define:GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE";
+            var sources = "*.cs";  // the generated sources from the TestProtos project
+            var args = $"-langversion:3 -target:library {compatibilityFlag} -reference:{testProtosOutputDir}\\Google.Protobuf.dll -out:{testProtosOutputDir}\\TestProtos.RefStructCompatibilityTest.OldCompiler.dll {sources}";
+            RunOldCsharpCompilerAndCheckSuccess(args, testProtosProjectDir);
+        }
+
+        /// <summary>
+        /// Invoke an old C# compiler in a subprocess and check it finished successful.
+        /// </summary>
+        /// <param name="args"></param>
+        /// <param name="workingDirectory"></param>
+        private void RunOldCsharpCompilerAndCheckSuccess(string args, string workingDirectory)
+        {
+            using var process = new Process();
+
+            // Get the path to the old C# 5 compiler from .NET framework. This approach is not 100% reliable, but works on most machines.
+            // Alternative way of getting the framework path is System.Runtime.InteropServices.RuntimeEnvironment.GetRuntimeDirectory()
+            // but it only works with the net45 target.
+            var oldCsharpCompilerPath = Path.Combine(Environment.GetEnvironmentVariable("WINDIR"), "Microsoft.NET", "Framework", "v4.0.30319", "csc.exe");
+            process.StartInfo.FileName = oldCsharpCompilerPath;
+            process.StartInfo.RedirectStandardOutput = true;
+            process.StartInfo.RedirectStandardError = true;
+            process.StartInfo.UseShellExecute = false;
+            process.StartInfo.Arguments = args;
+            process.StartInfo.WorkingDirectory = workingDirectory;
+
+            process.OutputDataReceived += (sender, e) =>
+            {
+                if (e.Data != null)
+                {
+                    Console.WriteLine(e.Data);
+                }
+            };
+            process.ErrorDataReceived += (sender, e) =>
+            {
+                if (e.Data != null)
+                {
+                    Console.WriteLine(e.Data);
+                }
+            };
+
+            process.Start();
+
+            process.BeginErrorReadLine();
+            process.BeginOutputReadLine();
+
+            process.WaitForExit();
+            Assert.AreEqual(0, process.ExitCode);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/Reflection/CustomOptionsTest.cs

@@ -0,0 +1,260 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2017 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using Google.Protobuf.Reflection;
+using NUnit.Framework;
+using System;
+using System.Linq;
+using UnitTest.Issues.TestProtos;
+using static UnitTest.Issues.TestProtos.ComplexOptionType2.Types;
+using static UnitTest.Issues.TestProtos.UnittestCustomOptionsProto3Extensions;
+using static UnitTest.Issues.TestProtos.DummyMessageContainingEnum.Types;
+using Google.Protobuf.TestProtos;
+
+#pragma warning disable CS0618
+
+namespace Google.Protobuf.Test.Reflection
+{
+    /// <summary>
+    /// The majority of the testing here is done via parsed descriptors. That's simpler to
+    /// achieve (and more important) than constructing a CodedInputStream manually.
+    /// </summary>
+    public class CustomOptionsTest
+    {
+        delegate bool OptionFetcher<T>(int field, out T value);
+
+        OptionFetcher<E> EnumFetcher<E>(CustomOptions options)
+        {
+            return (int i, out E v) => {
+                if (options.TryGetInt32(i, out int value))
+                {
+                    v = (E)(object)value;
+                    return true;
+                }
+                else
+                {
+                    v = default;
+                    return false;
+                }
+            };
+        }
+
+        [Test]
+        public void BuiltinOptionsCanBeRetrieved()
+        {
+            // non-custom options (that are not extensions but regular fields) can only be accessed via descriptor.Options
+            var fileOptions = UnittestProto3Reflection.Descriptor.GetOptions();
+            Assert.AreEqual("Google.Protobuf.TestProtos", fileOptions.CsharpNamespace);
+        }
+
+        [Test]
+        public void OptionPresenceCanBeDetected()
+        {
+            // case 1: the descriptor has no options at all so the options message is not present
+            Assert.IsNull(TestAllTypes.Descriptor.GetOptions());
+
+            // case 2: the descriptor has some options, but not the one we're looking for
+            // HasExtension will be false and GetExtension returns extension's default value
+            Assert.IsFalse(UnittestProto3Reflection.Descriptor.GetOptions().HasExtension(FileOpt1));
+            Assert.AreEqual(0, UnittestProto3Reflection.Descriptor.GetOptions().GetExtension(FileOpt1));
+
+            // case 3: option is present
+            Assert.IsTrue(UnittestCustomOptionsProto3Reflection.Descriptor.GetOptions().HasExtension(FileOpt1));
+            Assert.AreEqual(9876543210UL, UnittestCustomOptionsProto3Reflection.Descriptor.GetOptions().GetExtension(FileOpt1));
+        }
+
+        [Test]
+        public void ScalarOptions()
+        {
+            var d = CustomOptionOtherValues.Descriptor;
+            var customOptions = d.CustomOptions;
+            AssertOption(-100, customOptions.TryGetInt32, Int32Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(12.3456789f, customOptions.TryGetFloat, FloatOpt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(1.234567890123456789d, customOptions.TryGetDouble, DoubleOpt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption("Hello, \"World\"", customOptions.TryGetString, StringOpt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(ByteString.CopyFromUtf8("Hello\0World"), customOptions.TryGetBytes, BytesOpt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(TestEnumType.TestOptionEnumType2, EnumFetcher<TestEnumType>(customOptions), EnumOpt, d.GetOption, d.GetOptions().GetExtension);
+        }
+
+        [Test]
+        public void MessageOptions()
+        {
+            var d = VariousComplexOptions.Descriptor;
+            var customOptions = d.CustomOptions;
+            AssertOption(new ComplexOptionType1 { Foo = 42, Foo4 = { 99, 88 } }, customOptions.TryGetMessage, ComplexOpt1, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(new ComplexOptionType2
+            {
+                Baz = 987,
+                Bar = new ComplexOptionType1 { Foo = 743 },
+                Fred = new ComplexOptionType4 { Waldo = 321 },
+                Barney = { new ComplexOptionType4 { Waldo = 101 }, new ComplexOptionType4 { Waldo = 212 } }
+            },
+                customOptions.TryGetMessage, ComplexOpt2, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(new ComplexOptionType3 { Qux = 9 }, customOptions.TryGetMessage, ComplexOpt3, d.GetOption, d.GetOptions().GetExtension);
+        }
+
+        [Test]
+        public void OptionLocations()
+        {
+            var fileDescriptor = UnittestCustomOptionsProto3Reflection.Descriptor;
+            AssertOption(9876543210UL, fileDescriptor.CustomOptions.TryGetUInt64, FileOpt1, fileDescriptor.GetOption, fileDescriptor.GetOptions().GetExtension);
+
+            var messageDescriptor = TestMessageWithCustomOptions.Descriptor;
+            AssertOption(-56, messageDescriptor.CustomOptions.TryGetInt32, MessageOpt1, messageDescriptor.GetOption, messageDescriptor.GetOptions().GetExtension);
+
+            var fieldDescriptor = TestMessageWithCustomOptions.Descriptor.Fields["field1"];
+            AssertOption(8765432109UL, fieldDescriptor.CustomOptions.TryGetFixed64, FieldOpt1, fieldDescriptor.GetOption, fieldDescriptor.GetOptions().GetExtension);
+
+            var oneofDescriptor = TestMessageWithCustomOptions.Descriptor.Oneofs[0];
+            AssertOption(-99, oneofDescriptor.CustomOptions.TryGetInt32, OneofOpt1, oneofDescriptor.GetOption, oneofDescriptor.GetOptions().GetExtension);
+
+            var enumDescriptor = TestMessageWithCustomOptions.Descriptor.EnumTypes[0];
+            AssertOption(-789, enumDescriptor.CustomOptions.TryGetSFixed32, EnumOpt1, enumDescriptor.GetOption, enumDescriptor.GetOptions().GetExtension);
+
+            var enumValueDescriptor = TestMessageWithCustomOptions.Descriptor.EnumTypes[0].FindValueByNumber(2);
+            AssertOption(123, enumValueDescriptor.CustomOptions.TryGetInt32, EnumValueOpt1, enumValueDescriptor.GetOption, enumValueDescriptor.GetOptions().GetExtension);
+
+            var serviceDescriptor = UnittestCustomOptionsProto3Reflection.Descriptor.Services
+                .Single(s => s.Name == "TestServiceWithCustomOptions");
+            AssertOption(-9876543210, serviceDescriptor.CustomOptions.TryGetSInt64, ServiceOpt1, serviceDescriptor.GetOption, serviceDescriptor.GetOptions().GetExtension);
+
+            var methodDescriptor = serviceDescriptor.Methods[0];
+            AssertOption(UnitTest.Issues.TestProtos.MethodOpt1.Val2, EnumFetcher<UnitTest.Issues.TestProtos.MethodOpt1>(methodDescriptor.CustomOptions), UnittestCustomOptionsProto3Extensions.MethodOpt1, methodDescriptor.GetOption, methodDescriptor.GetOptions().GetExtension);
+        }
+
+        [Test]
+        public void MinValues()
+        {
+            var d = CustomOptionMinIntegerValues.Descriptor;
+            var customOptions = d.CustomOptions;
+            AssertOption(false, customOptions.TryGetBool, BoolOpt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(int.MinValue, customOptions.TryGetInt32, Int32Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(long.MinValue, customOptions.TryGetInt64, Int64Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(uint.MinValue, customOptions.TryGetUInt32, Uint32Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(ulong.MinValue, customOptions.TryGetUInt64, Uint64Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(int.MinValue, customOptions.TryGetSInt32, Sint32Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(long.MinValue, customOptions.TryGetSInt64, Sint64Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(uint.MinValue, customOptions.TryGetUInt32, Fixed32Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(ulong.MinValue, customOptions.TryGetUInt64, Fixed64Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(int.MinValue, customOptions.TryGetInt32, Sfixed32Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(long.MinValue, customOptions.TryGetInt64, Sfixed64Opt, d.GetOption, d.GetOptions().GetExtension);
+        }
+
+        [Test]
+        public void MaxValues()
+        {
+            var d = CustomOptionMaxIntegerValues.Descriptor;
+            var customOptions = d.CustomOptions;
+            AssertOption(true, customOptions.TryGetBool, BoolOpt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(int.MaxValue, customOptions.TryGetInt32, Int32Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(long.MaxValue, customOptions.TryGetInt64, Int64Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(uint.MaxValue, customOptions.TryGetUInt32, Uint32Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(ulong.MaxValue, customOptions.TryGetUInt64, Uint64Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(int.MaxValue, customOptions.TryGetSInt32, Sint32Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(long.MaxValue, customOptions.TryGetSInt64, Sint64Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(uint.MaxValue, customOptions.TryGetFixed32, Fixed32Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(ulong.MaxValue, customOptions.TryGetFixed64, Fixed64Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(int.MaxValue, customOptions.TryGetSFixed32, Sfixed32Opt, d.GetOption, d.GetOptions().GetExtension);
+            AssertOption(long.MaxValue, customOptions.TryGetSFixed64, Sfixed64Opt, d.GetOption, d.GetOptions().GetExtension);
+        }
+
+        [Test]
+        public void AggregateOptions()
+        {
+            // Just two examples
+            var messageDescriptor = AggregateMessage.Descriptor;
+            AssertOption(new Aggregate { I = 101, S = "MessageAnnotation" }, messageDescriptor.CustomOptions.TryGetMessage, Msgopt, messageDescriptor.GetOption, messageDescriptor.GetOptions().GetExtension);
+
+            var fieldDescriptor = messageDescriptor.Fields["fieldname"];
+            AssertOption(new Aggregate { S = "FieldAnnotation" }, fieldDescriptor.CustomOptions.TryGetMessage, Fieldopt, fieldDescriptor.GetOption, fieldDescriptor.GetOptions().GetExtension);
+        }
+
+        [Test]
+        public void NoOptions()
+        {
+            var fileDescriptor = UnittestProto3Reflection.Descriptor;
+            var messageDescriptor = TestAllTypes.Descriptor;
+            Assert.NotNull(fileDescriptor.CustomOptions);
+            Assert.NotNull(messageDescriptor.CustomOptions);
+            Assert.NotNull(messageDescriptor.Fields[1].CustomOptions);
+            Assert.NotNull(fileDescriptor.Services[0].CustomOptions);
+            Assert.NotNull(fileDescriptor.Services[0].Methods[0].CustomOptions);
+            Assert.NotNull(fileDescriptor.EnumTypes[0].CustomOptions);
+            Assert.NotNull(fileDescriptor.EnumTypes[0].Values[0].CustomOptions);
+            Assert.NotNull(TestAllTypes.Descriptor.Oneofs[0].CustomOptions);
+        }
+
+        [Test]
+        public void MultipleImportOfSameFileWithExtension()
+        {
+            var descriptor = UnittestIssue6936CReflection.Descriptor;
+            var foo = Foo.Descriptor;
+            var bar = Bar.Descriptor;
+            AssertOption("foo", foo.CustomOptions.TryGetString, UnittestIssue6936AExtensions.Opt, foo.GetOption, foo.GetOptions().GetExtension);
+            AssertOption("bar", bar.CustomOptions.TryGetString, UnittestIssue6936AExtensions.Opt, bar.GetOption, bar.GetOptions().GetExtension);
+        }
+
+        [Test]
+        public void SelfReferentialOptions()
+        {
+            // Custom field option used in definition of the custom option's message.
+            var fooField = UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions.Descriptor.FindFieldByName("foo");
+            var fooFieldFooExtensionValue = fooField.GetOptions().GetExtension(UnitTest.Issues.TestProtos.SelfreferentialOptions.UnittestSelfreferentialOptionsExtensions.FooOptions);
+            Assert.AreEqual(1234, fooFieldFooExtensionValue.Foo);
+
+            // Custom field option used on the definition of that field option.
+            var fileDescriptor = UnitTest.Issues.TestProtos.SelfreferentialOptions.UnittestSelfreferentialOptionsReflection.Descriptor;
+            var barOptionsField = fileDescriptor.Extensions.UnorderedExtensions.Single(field => field.Name == "bar_options");
+            var barExtensionValue = barOptionsField.GetOptions().GetExtension(UnitTest.Issues.TestProtos.SelfreferentialOptions.UnittestSelfreferentialOptionsExtensions.BarOptions);
+            Assert.AreEqual(1234, barExtensionValue);
+
+            // Custom field option used in definition of the extension message.
+            var intOptField = UnitTest.Issues.TestProtos.SelfreferentialOptions.FooOptions.Descriptor.FindFieldByName("int_opt");
+            var intOptFieldFooExtensionValue = intOptField.GetOptions().GetExtension(UnitTest.Issues.TestProtos.SelfreferentialOptions.UnittestSelfreferentialOptionsExtensions.FooOptions);
+            Assert.AreEqual(1, intOptFieldFooExtensionValue.IntOpt);
+            Assert.AreEqual(2, intOptFieldFooExtensionValue.GetExtension(UnitTest.Issues.TestProtos.SelfreferentialOptions.UnittestSelfreferentialOptionsExtensions.FooIntOpt));
+            Assert.AreEqual(3, intOptFieldFooExtensionValue.GetExtension(UnitTest.Issues.TestProtos.SelfreferentialOptions.UnittestSelfreferentialOptionsExtensions.FooFooOpt).IntOpt);
+        }
+
+        private void AssertOption<T, D>(T expected, OptionFetcher<T> customOptionFetcher, Extension<D, T> extension, Func<Extension<D, T>, T> getOptionFetcher, Func<Extension<D, T>, T> extensionFetcher) where D : IExtendableMessage<D>
+        {
+            Assert.IsTrue(customOptionFetcher(extension.FieldNumber, out T customOptionsValue));
+            Assert.AreEqual(expected, customOptionsValue);
+
+            T getOptionValue = getOptionFetcher(extension);
+            Assert.AreEqual(expected, getOptionValue);
+
+            T extensionValue = extensionFetcher(extension);
+            Assert.AreEqual(expected, extensionValue);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/Reflection/DescriptorDeclarationTest.cs

@@ -0,0 +1,175 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2018 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using Google.Protobuf.Reflection;
+using NUnit.Framework;
+using System.Linq;
+using System.Reflection;
+
+namespace Google.Protobuf.Test.Reflection
+{
+    // In reality this isn't a test for DescriptorDeclaration so much as the way they're loaded.
+    public class DescriptorDeclarationTest
+    {
+        static readonly FileDescriptor unitTestProto3Descriptor = LoadProtos();
+
+        // Note: we don't expose a declaration for FileDescriptor as it doesn't have comments
+        // at the moment and the locations aren't terribly useful.
+
+        // The tests for most elements are quite basic: we don't test every aspect of every element.
+        // The code within the library falls into two categories:
+        // - Exposing the properties for *any* declaration
+        // - Finding the right declaration for an element from the descriptor data
+        // We have a per-element check to make sure we *are* finding the right declaration, and we
+        // check every property of declarations in at least one test, but we don't have a cross-product.
+        // That would effectively be testing protoc, which seems redundant here.
+
+        [Test]
+        public void ServiceComments()
+        {
+            var service = unitTestProto3Descriptor.FindTypeByName<ServiceDescriptor>("TestService");
+            Assert.NotNull(service.Declaration);
+            Assert.AreEqual(" This is a test service\n", service.Declaration.LeadingComments);
+        }
+
+        [Test]
+        public void MethodComments()
+        {
+            var service = unitTestProto3Descriptor.FindTypeByName<ServiceDescriptor>("TestService");
+            var method = service.FindMethodByName("Foo");
+            Assert.NotNull(method.Declaration);
+            Assert.AreEqual(" This is a test method\n", method.Declaration.LeadingComments);
+        }
+
+        [Test]
+        public void MessageComments()
+        {
+            var message = unitTestProto3Descriptor.FindTypeByName<MessageDescriptor>("CommentMessage");
+            Assert.NotNull(message.Declaration);
+            Assert.AreEqual(" This is a leading comment\n", message.Declaration.LeadingComments);
+            Assert.AreEqual(new[] { " This is leading detached comment 1\n", " This is leading detached comment 2\n" },
+                message.Declaration.LeadingDetachedComments);
+        }
+
+        // Note: this test is somewhat brittle; a change earlier in the proto will break it.
+        [Test]
+        public void MessageLocations()
+        {
+            var message = unitTestProto3Descriptor.FindTypeByName<MessageDescriptor>("CommentMessage");
+            Assert.NotNull(message.Declaration);
+            Assert.AreEqual(389, message.Declaration.StartLine);
+            Assert.AreEqual(1, message.Declaration.StartColumn);
+
+            Assert.AreEqual(404, message.Declaration.EndLine);
+            Assert.AreEqual(2, message.Declaration.EndColumn);
+        }
+
+        [Test]
+        public void EnumComments()
+        {
+            var descriptor = unitTestProto3Descriptor.FindTypeByName<EnumDescriptor>("CommentEnum");
+            Assert.NotNull(descriptor.Declaration);
+            Assert.AreEqual(" Leading enum comment\n", descriptor.Declaration.LeadingComments);
+        }
+
+        [Test]
+        public void NestedMessageComments()
+        {
+            var outer = unitTestProto3Descriptor.FindTypeByName<MessageDescriptor>("CommentMessage");
+            var nested = outer.FindDescriptor<MessageDescriptor>("NestedCommentMessage");
+            Assert.NotNull(nested.Declaration);
+            Assert.AreEqual(" Leading nested message comment\n", nested.Declaration.LeadingComments);
+        }
+
+        [Test]
+        public void NestedEnumComments()
+        {
+            var outer = unitTestProto3Descriptor.FindTypeByName<MessageDescriptor>("CommentMessage");
+            var nested = outer.FindDescriptor<EnumDescriptor>("NestedCommentEnum");
+            Assert.NotNull(nested.Declaration);
+            Assert.AreEqual(" Leading nested enum comment\n", nested.Declaration.LeadingComments);
+        }
+
+        [Test]
+        public void FieldComments()
+        {
+            var message = unitTestProto3Descriptor.FindTypeByName<MessageDescriptor>("CommentMessage");
+            var field = message.FindFieldByName("text");
+            Assert.NotNull(field.Declaration);
+            Assert.AreEqual(" Leading field comment\n", field.Declaration.LeadingComments);
+            Assert.AreEqual(" Trailing field comment\n", field.Declaration.TrailingComments);
+        }
+
+        [Test]
+        public void NestedMessageFieldComments()
+        {
+            var outer = unitTestProto3Descriptor.FindTypeByName<MessageDescriptor>("CommentMessage");
+            var nested = outer.FindDescriptor<MessageDescriptor>("NestedCommentMessage");
+            var field = nested.FindFieldByName("nested_text");
+            Assert.NotNull(field.Declaration);
+            Assert.AreEqual(" Leading nested message field comment\n", field.Declaration.LeadingComments);
+        }
+
+        [Test]
+        public void EnumValueComments()
+        {
+            var enumDescriptor = unitTestProto3Descriptor.FindTypeByName<EnumDescriptor>("CommentEnum");
+            var value = enumDescriptor.FindValueByName("ZERO_VALUE");
+            Assert.NotNull(value.Declaration);
+            Assert.AreEqual(" Zero value comment\n", value.Declaration.LeadingComments);
+        }
+
+        [Test]
+        public void NestedEnumValueComments()
+        {
+            var outer = unitTestProto3Descriptor.FindTypeByName<MessageDescriptor>("CommentMessage");
+            var nested = outer.FindDescriptor<EnumDescriptor>("NestedCommentEnum");
+            var value = nested.FindValueByName("ZERO_VALUE");
+            Assert.NotNull(value.Declaration);
+            Assert.AreEqual(" Zero value comment\n", value.Declaration.LeadingComments);
+        }
+
+        private static FileDescriptor LoadProtos()
+        {
+            var type = typeof(DescriptorDeclarationTest);
+            // TODO: Make this simpler :)
+            FileDescriptorSet descriptorSet;
+            using (var stream = type.GetTypeInfo().Assembly.GetManifestResourceStream($"Google.Protobuf.Test.testprotos.pb"))
+            {
+                descriptorSet = FileDescriptorSet.Parser.ParseFrom(stream);
+            }
+            var byteStrings = descriptorSet.File.Select(f => f.ToByteString()).ToList();
+            var descriptors = FileDescriptor.BuildFromByteStrings(byteStrings);
+            return descriptors.Single(d => d.Name == "unittest_proto3.proto");
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/Reflection/DescriptorsTest.cs

@@ -0,0 +1,480 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using Google.Protobuf.TestProtos;
+using NUnit.Framework;
+using ProtobufUnittest;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using UnitTest.Issues.TestProtos;
+
+namespace Google.Protobuf.Reflection
+{
+    /// <summary>
+    /// Tests for descriptors. (Not in its own namespace or broken up into individual classes as the
+    /// size doesn't warrant it. On the other hand, this makes me feel a bit dirty...)
+    /// </summary>
+    public class DescriptorsTest
+    {
+        [Test]
+        public void FileDescriptor_GeneratedCode()
+        {
+            TestFileDescriptor(
+                UnittestProto3Reflection.Descriptor,
+                UnittestImportProto3Reflection.Descriptor,
+                UnittestImportPublicProto3Reflection.Descriptor);
+        }
+
+        [Test]
+        public void FileDescriptor_BuildFromByteStrings()
+        {
+            // The descriptors have to be supplied in an order such that all the
+            // dependencies come before the descriptors depending on them.
+            var descriptorData = new List<ByteString>
+            {
+                UnittestImportPublicProto3Reflection.Descriptor.SerializedData,
+                UnittestImportProto3Reflection.Descriptor.SerializedData,
+                UnittestProto3Reflection.Descriptor.SerializedData
+            };
+            var converted = FileDescriptor.BuildFromByteStrings(descriptorData);
+            Assert.AreEqual(3, converted.Count);
+            TestFileDescriptor(converted[2], converted[1], converted[0]);
+        }
+
+        [Test]
+        public void FileDescriptor_BuildFromByteStrings_WithExtensionRegistry()
+        {
+            var extension = UnittestCustomOptionsProto3Extensions.MessageOpt1;
+
+            var byteStrings = new[]
+            {
+                DescriptorReflection.Descriptor.Proto.ToByteString(),
+                UnittestCustomOptionsProto3Reflection.Descriptor.Proto.ToByteString()
+            };
+            var registry = new ExtensionRegistry { extension };
+
+            var descriptor = FileDescriptor.BuildFromByteStrings(byteStrings, registry).Last();
+            var message = descriptor.MessageTypes.Single(t => t.Name == nameof(TestMessageWithCustomOptions));
+            var extensionValue = message.GetOptions().GetExtension(extension);
+            Assert.AreEqual(-56, extensionValue);
+        }
+
+        private void TestFileDescriptor(FileDescriptor file, FileDescriptor importedFile, FileDescriptor importedPublicFile)
+        {
+            Assert.AreEqual("unittest_proto3.proto", file.Name);
+            Assert.AreEqual("protobuf_unittest3", file.Package);
+
+            Assert.AreEqual("UnittestProto", file.Proto.Options.JavaOuterClassname);
+            Assert.AreEqual("unittest_proto3.proto", file.Proto.Name);
+
+            // unittest_proto3.proto doesn't have any public imports, but unittest_import_proto3.proto does.
+            Assert.AreEqual(0, file.PublicDependencies.Count);
+            Assert.AreEqual(1, importedFile.PublicDependencies.Count);
+            Assert.AreEqual(importedPublicFile, importedFile.PublicDependencies[0]);
+
+            Assert.AreEqual(1, file.Dependencies.Count);
+            Assert.AreEqual(importedFile, file.Dependencies[0]);
+
+            Assert.Null(file.FindTypeByName<MessageDescriptor>("NoSuchType"));
+            Assert.Null(file.FindTypeByName<MessageDescriptor>("protobuf_unittest3.TestAllTypes"));
+            for (int i = 0; i < file.MessageTypes.Count; i++)
+            {
+                Assert.AreEqual(i, file.MessageTypes[i].Index);
+            }
+
+            Assert.AreEqual(file.EnumTypes[0], file.FindTypeByName<EnumDescriptor>("ForeignEnum"));
+            Assert.Null(file.FindTypeByName<EnumDescriptor>("NoSuchType"));
+            Assert.Null(file.FindTypeByName<EnumDescriptor>("protobuf_unittest3.ForeignEnum"));
+            Assert.AreEqual(1, importedFile.EnumTypes.Count);
+            Assert.AreEqual("ImportEnum", importedFile.EnumTypes[0].Name);
+            for (int i = 0; i < file.EnumTypes.Count; i++)
+            {
+                Assert.AreEqual(i, file.EnumTypes[i].Index);
+            }
+
+            Assert.AreEqual(10, file.SerializedData[0]);
+            TestDescriptorToProto(file.ToProto, file.Proto);
+        }
+
+        [Test]
+        public void FileDescriptor_NonRootPath()
+        {
+            // unittest_proto3.proto used to be in google/protobuf. Now it's in the C#-specific location,
+            // let's test something that's still in a directory.
+            FileDescriptor file = UnittestWellKnownTypesReflection.Descriptor;
+            Assert.AreEqual("google/protobuf/unittest_well_known_types.proto", file.Name);
+            Assert.AreEqual("protobuf_unittest", file.Package);
+        }
+
+        [Test]
+        public void FileDescriptor_BuildFromByteStrings_MissingDependency()
+        {
+            var descriptorData = new List<ByteString>
+            {
+                UnittestImportProto3Reflection.Descriptor.SerializedData,
+                UnittestProto3Reflection.Descriptor.SerializedData,
+            };
+            // This will fail, because we're missing UnittestImportPublicProto3Reflection
+            Assert.Throws<ArgumentException>(() => FileDescriptor.BuildFromByteStrings(descriptorData));
+        }
+
+        [Test]
+        public void FileDescriptor_BuildFromByteStrings_DuplicateNames()
+        {
+            var descriptorData = new List<ByteString>
+            {
+                UnittestImportPublicProto3Reflection.Descriptor.SerializedData,
+                UnittestImportPublicProto3Reflection.Descriptor.SerializedData,
+            };
+            // This will fail due to the same name being used twice
+            Assert.Throws<ArgumentException>(() => FileDescriptor.BuildFromByteStrings(descriptorData));
+        }
+
+        [Test]
+        public void FileDescriptor_BuildFromByteStrings_IncorrectOrder()
+        {
+            var descriptorData = new List<ByteString>
+            {
+                UnittestProto3Reflection.Descriptor.SerializedData,
+                UnittestImportPublicProto3Reflection.Descriptor.SerializedData,
+                UnittestImportProto3Reflection.Descriptor.SerializedData
+            };
+            // This will fail, because the dependencies should come first
+            Assert.Throws<ArgumentException>(() => FileDescriptor.BuildFromByteStrings(descriptorData));
+
+        }
+
+        [Test]
+        public void MessageDescriptorFromGeneratedCodeFileDescriptor()
+        {
+            var file = UnittestProto3Reflection.Descriptor;
+
+            MessageDescriptor messageType = TestAllTypes.Descriptor;
+            Assert.AreSame(typeof(TestAllTypes), messageType.ClrType);
+            Assert.AreSame(TestAllTypes.Parser, messageType.Parser);
+            Assert.AreEqual(messageType, file.MessageTypes[0]);
+            Assert.AreEqual(messageType, file.FindTypeByName<MessageDescriptor>("TestAllTypes"));
+        }
+
+        [Test]
+        public void MessageDescriptor()
+        {
+            MessageDescriptor messageType = TestAllTypes.Descriptor;
+            MessageDescriptor nestedType = TestAllTypes.Types.NestedMessage.Descriptor;
+
+            Assert.AreEqual("TestAllTypes", messageType.Name);
+            Assert.AreEqual("protobuf_unittest3.TestAllTypes", messageType.FullName);
+            Assert.AreEqual(UnittestProto3Reflection.Descriptor, messageType.File);
+            Assert.IsNull(messageType.ContainingType);
+            Assert.IsNull(messageType.Proto.Options);
+
+            Assert.AreEqual("TestAllTypes", messageType.Name);
+
+            Assert.AreEqual("NestedMessage", nestedType.Name);
+            Assert.AreEqual("protobuf_unittest3.TestAllTypes.NestedMessage", nestedType.FullName);
+            Assert.AreEqual(UnittestProto3Reflection.Descriptor, nestedType.File);
+            Assert.AreEqual(messageType, nestedType.ContainingType);
+
+            FieldDescriptor field = messageType.Fields.InDeclarationOrder()[0];
+            Assert.AreEqual("single_int32", field.Name);
+            Assert.AreEqual(field, messageType.FindDescriptor<FieldDescriptor>("single_int32"));
+            Assert.Null(messageType.FindDescriptor<FieldDescriptor>("no_such_field"));
+            Assert.AreEqual(field, messageType.FindFieldByNumber(1));
+            Assert.Null(messageType.FindFieldByNumber(571283));
+            var fieldsInDeclarationOrder = messageType.Fields.InDeclarationOrder();
+            for (int i = 0; i < fieldsInDeclarationOrder.Count; i++)
+            {
+                Assert.AreEqual(i, fieldsInDeclarationOrder[i].Index);
+            }
+
+            Assert.AreEqual(nestedType, messageType.NestedTypes[0]);
+            Assert.AreEqual(nestedType, messageType.FindDescriptor<MessageDescriptor>("NestedMessage"));
+            Assert.Null(messageType.FindDescriptor<MessageDescriptor>("NoSuchType"));
+            for (int i = 0; i < messageType.NestedTypes.Count; i++)
+            {
+                Assert.AreEqual(i, messageType.NestedTypes[i].Index);
+            }
+
+            Assert.AreEqual(messageType.EnumTypes[0], messageType.FindDescriptor<EnumDescriptor>("NestedEnum"));
+            Assert.Null(messageType.FindDescriptor<EnumDescriptor>("NoSuchType"));
+            for (int i = 0; i < messageType.EnumTypes.Count; i++)
+            {
+                Assert.AreEqual(i, messageType.EnumTypes[i].Index);
+            }
+            TestDescriptorToProto(messageType.ToProto, messageType.Proto);
+        }
+
+        [Test]
+        public void FieldDescriptor_GeneratedCode()
+        {
+            TestFieldDescriptor(UnittestProto3Reflection.Descriptor, TestAllTypes.Descriptor, ForeignMessage.Descriptor, ImportMessage.Descriptor);
+        }
+
+        [Test]
+        public void FieldDescriptor_BuildFromByteStrings()
+        {
+            // The descriptors have to be supplied in an order such that all the
+            // dependencies come before the descriptors depending on them.
+            var descriptorData = new List<ByteString>
+            {
+                UnittestImportPublicProto3Reflection.Descriptor.SerializedData,
+                UnittestImportProto3Reflection.Descriptor.SerializedData,
+                UnittestProto3Reflection.Descriptor.SerializedData
+            };
+            var converted = FileDescriptor.BuildFromByteStrings(descriptorData);
+            TestFieldDescriptor(
+                converted[2],
+                converted[2].FindTypeByName<MessageDescriptor>("TestAllTypes"),
+                converted[2].FindTypeByName<MessageDescriptor>("ForeignMessage"),
+                converted[1].FindTypeByName<MessageDescriptor>("ImportMessage"));
+        }
+
+        public void TestFieldDescriptor(
+            FileDescriptor unitTestProto3Descriptor,
+            MessageDescriptor testAllTypesDescriptor,
+            MessageDescriptor foreignMessageDescriptor,
+            MessageDescriptor importMessageDescriptor)
+        {
+            FieldDescriptor primitiveField = testAllTypesDescriptor.FindDescriptor<FieldDescriptor>("single_int32");
+            FieldDescriptor enumField = testAllTypesDescriptor.FindDescriptor<FieldDescriptor>("single_nested_enum");
+            FieldDescriptor foreignMessageField = testAllTypesDescriptor.FindDescriptor<FieldDescriptor>("single_foreign_message");
+            FieldDescriptor importMessageField = testAllTypesDescriptor.FindDescriptor<FieldDescriptor>("single_import_message");
+            FieldDescriptor fieldInOneof = testAllTypesDescriptor.FindDescriptor<FieldDescriptor>("oneof_string");
+
+            Assert.AreEqual("single_int32", primitiveField.Name);
+            Assert.AreEqual("protobuf_unittest3.TestAllTypes.single_int32",
+                            primitiveField.FullName);
+            Assert.AreEqual(1, primitiveField.FieldNumber);
+            Assert.AreEqual(testAllTypesDescriptor, primitiveField.ContainingType);
+            Assert.AreEqual(unitTestProto3Descriptor, primitiveField.File);
+            Assert.AreEqual(FieldType.Int32, primitiveField.FieldType);
+            Assert.IsNull(primitiveField.Proto.Options);
+
+            Assert.AreEqual("single_nested_enum", enumField.Name);
+            Assert.AreEqual(FieldType.Enum, enumField.FieldType);
+            Assert.AreEqual(testAllTypesDescriptor.EnumTypes[0], enumField.EnumType);
+
+            Assert.AreEqual("single_foreign_message", foreignMessageField.Name);
+            Assert.AreEqual(FieldType.Message, foreignMessageField.FieldType);
+            Assert.AreEqual(foreignMessageDescriptor, foreignMessageField.MessageType);
+
+            Assert.AreEqual("single_import_message", importMessageField.Name);
+            Assert.AreEqual(FieldType.Message, importMessageField.FieldType);
+            Assert.AreEqual(importMessageDescriptor, importMessageField.MessageType);
+
+            // For a field in a regular onoef, ContainingOneof and RealContainingOneof should be the same.
+            Assert.AreEqual("oneof_field", fieldInOneof.ContainingOneof.Name);
+            Assert.AreSame(fieldInOneof.ContainingOneof, fieldInOneof.RealContainingOneof);
+
+            TestDescriptorToProto(primitiveField.ToProto, primitiveField.Proto);
+            TestDescriptorToProto(enumField.ToProto, enumField.Proto);
+            TestDescriptorToProto(foreignMessageField.ToProto, foreignMessageField.Proto);
+            TestDescriptorToProto(fieldInOneof.ToProto, fieldInOneof.Proto);
+        }
+
+        [Test]
+        public void FieldDescriptorLabel()
+        {
+            FieldDescriptor singleField =
+                TestAllTypes.Descriptor.FindDescriptor<FieldDescriptor>("single_int32");
+            FieldDescriptor repeatedField =
+                TestAllTypes.Descriptor.FindDescriptor<FieldDescriptor>("repeated_int32");
+
+            Assert.IsFalse(singleField.IsRepeated);
+            Assert.IsTrue(repeatedField.IsRepeated);
+        }
+
+        [Test]
+        public void EnumDescriptor()
+        {
+            // Note: this test is a bit different to the Java version because there's no static way of getting to the descriptor
+            EnumDescriptor enumType = UnittestProto3Reflection.Descriptor.FindTypeByName<EnumDescriptor>("ForeignEnum");
+            EnumDescriptor nestedType = TestAllTypes.Descriptor.FindDescriptor<EnumDescriptor>("NestedEnum");
+
+            Assert.AreEqual("ForeignEnum", enumType.Name);
+            Assert.AreEqual("protobuf_unittest3.ForeignEnum", enumType.FullName);
+            Assert.AreEqual(UnittestProto3Reflection.Descriptor, enumType.File);
+            Assert.Null(enumType.ContainingType);
+            Assert.Null(enumType.Proto.Options);
+
+            Assert.AreEqual("NestedEnum", nestedType.Name);
+            Assert.AreEqual("protobuf_unittest3.TestAllTypes.NestedEnum",
+                            nestedType.FullName);
+            Assert.AreEqual(UnittestProto3Reflection.Descriptor, nestedType.File);
+            Assert.AreEqual(TestAllTypes.Descriptor, nestedType.ContainingType);
+
+            EnumValueDescriptor value = enumType.FindValueByName("FOREIGN_FOO");
+            Assert.AreEqual(value, enumType.Values[1]);
+            Assert.AreEqual("FOREIGN_FOO", value.Name);
+            Assert.AreEqual(4, value.Number);
+            Assert.AreEqual((int) ForeignEnum.ForeignFoo, value.Number);
+            Assert.AreEqual(value, enumType.FindValueByNumber(4));
+            Assert.Null(enumType.FindValueByName("NO_SUCH_VALUE"));
+            for (int i = 0; i < enumType.Values.Count; i++)
+            {
+                Assert.AreEqual(i, enumType.Values[i].Index);
+            }
+            TestDescriptorToProto(enumType.ToProto, enumType.Proto);
+            TestDescriptorToProto(nestedType.ToProto, nestedType.Proto);
+        }
+
+        [Test]
+        public void OneofDescriptor()
+        {
+            OneofDescriptor descriptor = TestAllTypes.Descriptor.FindDescriptor<OneofDescriptor>("oneof_field");
+            Assert.IsFalse(descriptor.IsSynthetic);
+            Assert.AreEqual("oneof_field", descriptor.Name);
+            Assert.AreEqual("protobuf_unittest3.TestAllTypes.oneof_field", descriptor.FullName);
+
+            var expectedFields = new[] {
+                TestAllTypes.OneofBytesFieldNumber,
+                TestAllTypes.OneofNestedMessageFieldNumber,
+                TestAllTypes.OneofStringFieldNumber,
+                TestAllTypes.OneofUint32FieldNumber }
+                .Select(fieldNumber => TestAllTypes.Descriptor.FindFieldByNumber(fieldNumber))
+                .ToList();
+            foreach (var field in expectedFields)
+            {
+                Assert.AreSame(descriptor, field.ContainingOneof);
+            }
+
+            CollectionAssert.AreEquivalent(expectedFields, descriptor.Fields);
+            TestDescriptorToProto(descriptor.ToProto, descriptor.Proto);
+        }
+
+        [Test]
+        public void MapEntryMessageDescriptor()
+        {
+            var descriptor = MapWellKnownTypes.Descriptor.NestedTypes[0];
+            Assert.IsNull(descriptor.Parser);
+            Assert.IsNull(descriptor.ClrType);
+            Assert.IsNull(descriptor.Fields[1].Accessor);
+            TestDescriptorToProto(descriptor.ToProto, descriptor.Proto);
+        }
+
+        // From TestFieldOrdering:
+        // string my_string = 11;
+        // int64 my_int = 1;
+        // float my_float = 101;
+        // NestedMessage single_nested_message = 200;
+        [Test]
+        public void FieldListOrderings()
+        {
+            var fields = TestFieldOrderings.Descriptor.Fields;
+            Assert.AreEqual(new[] { 11, 1, 101, 200 }, fields.InDeclarationOrder().Select(x => x.FieldNumber));
+            Assert.AreEqual(new[] { 1, 11, 101, 200 }, fields.InFieldNumberOrder().Select(x => x.FieldNumber));
+        }
+
+
+        [Test]
+        public void DescriptorProtoFileDescriptor()
+        {
+            var descriptor = Google.Protobuf.Reflection.FileDescriptor.DescriptorProtoFileDescriptor;
+            Assert.AreEqual("google/protobuf/descriptor.proto", descriptor.Name);
+            TestDescriptorToProto(descriptor.ToProto, descriptor.Proto);
+        }
+
+        [Test]
+        public void DescriptorImportingExtensionsFromOldCodeGen()
+        {
+            // The extension collection includes a null extension. There's not a lot we can do about that
+            // in itself, as the old generator didn't provide us the extension information.
+            var extensions = TestProtos.OldGenerator.OldExtensions2Reflection.Descriptor.Extensions;
+            Assert.AreEqual(1, extensions.UnorderedExtensions.Count);
+            // Note: this assertion is present so that it will fail if OldExtensions2 is regenerated
+            // with a new generator.
+            Assert.Null(extensions.UnorderedExtensions[0].Extension);
+
+            // ... but we can make sure we at least don't cause a failure when retrieving descriptors.
+            // In particular, old_extensions1.proto imports old_extensions2.proto, and this used to cause
+            // an execution-time failure.
+            var importingDescriptor = TestProtos.OldGenerator.OldExtensions1Reflection.Descriptor;
+            Assert.NotNull(importingDescriptor);
+        }
+
+        [Test]
+        public void Proto3OptionalDescriptors()
+        {
+            var descriptor = TestProto3Optional.Descriptor;
+            var field = descriptor.Fields[TestProto3Optional.OptionalInt32FieldNumber];
+            Assert.NotNull(field.ContainingOneof);
+            Assert.IsTrue(field.ContainingOneof.IsSynthetic);
+            Assert.Null(field.RealContainingOneof);
+        }
+
+
+        [Test]
+        public void SyntheticOneofReflection()
+        {
+            // Expect every oneof in TestProto3Optional to be synthetic
+            var proto3OptionalDescriptor = TestProto3Optional.Descriptor;
+            Assert.AreEqual(0, proto3OptionalDescriptor.RealOneofCount);
+            foreach (var oneof in proto3OptionalDescriptor.Oneofs)
+            {
+                Assert.True(oneof.IsSynthetic);
+            }
+
+            // Expect no oneof in the original proto3 unit test file to be synthetic.
+            foreach (var descriptor in ProtobufTestMessages.Proto3.TestMessagesProto3Reflection.Descriptor.MessageTypes)
+            {
+                Assert.AreEqual(descriptor.Oneofs.Count, descriptor.RealOneofCount);
+                foreach (var oneof in descriptor.Oneofs)
+                {
+                    Assert.False(oneof.IsSynthetic);
+                }
+            }
+
+            // Expect no oneof in the original proto2 unit test file to be synthetic.
+            foreach (var descriptor in ProtobufTestMessages.Proto2.TestMessagesProto2Reflection.Descriptor.MessageTypes)
+            {
+                Assert.AreEqual(descriptor.Oneofs.Count, descriptor.RealOneofCount);
+                foreach (var oneof in descriptor.Oneofs)
+                {
+                    Assert.False(oneof.IsSynthetic);
+                }
+            }
+        }
+
+        private static void TestDescriptorToProto(Func<IMessage> toProtoFunction, IMessage expectedProto)
+        {
+            var clone1 = toProtoFunction();
+            var clone2 = toProtoFunction();
+            Assert.AreNotSame(clone1, clone2);
+            Assert.AreNotSame(clone1, expectedProto);
+            Assert.AreNotSame(clone2, expectedProto);
+
+            Assert.AreEqual(clone1, clone2);
+            Assert.AreEqual(clone1, expectedProto);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/Reflection/FieldAccessTest.cs

@@ -0,0 +1,436 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using Google.Protobuf.TestProtos;
+using Proto2 = Google.Protobuf.TestProtos.Proto2;
+using NUnit.Framework;
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+using static Google.Protobuf.TestProtos.Proto2.UnittestExtensions;
+using ProtobufUnittest;
+
+namespace Google.Protobuf.Reflection
+{
+    public class FieldAccessTest
+    {
+        [Test]
+        public void GetValue()
+        {
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var fields = TestProtos.TestAllTypes.Descriptor.Fields;
+            Assert.AreEqual(message.SingleBool, fields[TestProtos.TestAllTypes.SingleBoolFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleBytes, fields[TestProtos.TestAllTypes.SingleBytesFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleDouble, fields[TestProtos.TestAllTypes.SingleDoubleFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleFixed32, fields[TestProtos.TestAllTypes.SingleFixed32FieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleFixed64, fields[TestProtos.TestAllTypes.SingleFixed64FieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleFloat, fields[TestProtos.TestAllTypes.SingleFloatFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleForeignEnum, fields[TestProtos.TestAllTypes.SingleForeignEnumFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleForeignMessage, fields[TestProtos.TestAllTypes.SingleForeignMessageFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleImportEnum, fields[TestProtos.TestAllTypes.SingleImportEnumFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleImportMessage, fields[TestProtos.TestAllTypes.SingleImportMessageFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleInt32, fields[TestProtos.TestAllTypes.SingleInt32FieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleInt64, fields[TestProtos.TestAllTypes.SingleInt64FieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleNestedEnum, fields[TestProtos.TestAllTypes.SingleNestedEnumFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleNestedMessage, fields[TestProtos.TestAllTypes.SingleNestedMessageFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SinglePublicImportMessage, fields[TestProtos.TestAllTypes.SinglePublicImportMessageFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleSint32, fields[TestProtos.TestAllTypes.SingleSint32FieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleSint64, fields[TestProtos.TestAllTypes.SingleSint64FieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleString, fields[TestProtos.TestAllTypes.SingleStringFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleSfixed32, fields[TestProtos.TestAllTypes.SingleSfixed32FieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleSfixed64, fields[TestProtos.TestAllTypes.SingleSfixed64FieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleUint32, fields[TestProtos.TestAllTypes.SingleUint32FieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.SingleUint64, fields[TestProtos.TestAllTypes.SingleUint64FieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.OneofBytes, fields[TestProtos.TestAllTypes.OneofBytesFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.OneofString, fields[TestProtos.TestAllTypes.OneofStringFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.OneofNestedMessage, fields[TestProtos.TestAllTypes.OneofNestedMessageFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(message.OneofUint32, fields[TestProtos.TestAllTypes.OneofUint32FieldNumber].Accessor.GetValue(message));
+
+            // Just one example for repeated fields - they're all just returning the list
+            var list = (IList) fields[TestProtos.TestAllTypes.RepeatedInt32FieldNumber].Accessor.GetValue(message);
+            Assert.AreEqual(message.RepeatedInt32, list);
+            Assert.AreEqual(message.RepeatedInt32[0], list[0]); // Just in case there was any doubt...
+
+            // Just a single map field, for the same reason
+            var mapMessage = new TestMap { MapStringString = { { "key1", "value1" }, { "key2", "value2" } } };
+            fields = TestMap.Descriptor.Fields;
+            var dictionary = (IDictionary) fields[TestMap.MapStringStringFieldNumber].Accessor.GetValue(mapMessage);
+            Assert.AreEqual(mapMessage.MapStringString, dictionary);
+            Assert.AreEqual("value1", dictionary["key1"]);
+        }
+
+        [Test]
+        public void GetValue_IncorrectType()
+        {
+            IMessage message = SampleMessages.CreateFullTestAllTypes();
+            var fields = message.Descriptor.Fields;
+            Assert.Throws<InvalidCastException>(() => fields[TestProtos.TestAllTypes.SingleBoolFieldNumber].Accessor.GetValue(new TestMap()));
+        }
+
+        [Test]
+        public void HasValue_Proto3_Message()
+        {
+            var message = new TestAllTypes();
+            var accessor = ((IMessage) message).Descriptor.Fields[TestProtos.TestAllTypes.SingleForeignMessageFieldNumber].Accessor;
+            Assert.False(accessor.HasValue(message));
+            message.SingleForeignMessage = new ForeignMessage();
+            Assert.True(accessor.HasValue(message));
+            message.SingleForeignMessage = null;
+            Assert.False(accessor.HasValue(message));
+        }
+
+        [Test]
+        public void HasValue_Proto3_Oneof()
+        {
+            TestAllTypes message = new TestAllTypes();
+            var accessor = ((IMessage) message).Descriptor.Fields[TestProtos.TestAllTypes.OneofStringFieldNumber].Accessor;
+            Assert.False(accessor.HasValue(message));
+            // Even though it's the default value, we still have a value.
+            message.OneofString = "";
+            Assert.True(accessor.HasValue(message));
+            message.OneofString = "hello";
+            Assert.True(accessor.HasValue(message));
+            message.OneofUint32 = 10;
+            Assert.False(accessor.HasValue(message));
+        }
+
+        [Test]
+        public void HasValue_Proto3_Primitive_Optional()
+        {
+            var message = new TestProto3Optional();
+            var accessor = ((IMessage) message).Descriptor.Fields[TestProto3Optional.OptionalInt64FieldNumber].Accessor;
+            Assert.IsFalse(accessor.HasValue(message));
+            message.OptionalInt64 = 5L;
+            Assert.IsTrue(accessor.HasValue(message));
+            message.ClearOptionalInt64();
+            Assert.IsFalse(accessor.HasValue(message));
+            message.OptionalInt64 = 0L;
+            Assert.IsTrue(accessor.HasValue(message));
+        }
+
+        [Test]
+        public void HasValue_Proto3_Primitive_NotOptional()
+        {
+            IMessage message = SampleMessages.CreateFullTestAllTypes();
+            var fields = message.Descriptor.Fields;
+            Assert.Throws<InvalidOperationException>(() => fields[TestProtos.TestAllTypes.SingleBoolFieldNumber].Accessor.HasValue(message));
+        }
+
+        [Test]
+        public void HasValue_Proto3_Repeated()
+        {
+            var message = new TestAllTypes();
+            var accessor = ((IMessage) message).Descriptor.Fields[TestProtos.TestAllTypes.RepeatedBoolFieldNumber].Accessor;
+            Assert.Throws<InvalidOperationException>(() => accessor.HasValue(message));
+        }
+
+        [Test]
+        public void HasValue_Proto2_Primitive()
+        {
+            var message = new Proto2.TestAllTypes();
+            var accessor = ((IMessage) message).Descriptor.Fields[Proto2.TestAllTypes.OptionalInt64FieldNumber].Accessor;
+
+            Assert.IsFalse(accessor.HasValue(message));
+            message.OptionalInt64 = 5L;
+            Assert.IsTrue(accessor.HasValue(message));
+            message.ClearOptionalInt64();
+            Assert.IsFalse(accessor.HasValue(message));
+            message.OptionalInt64 = 0L;
+            Assert.IsTrue(accessor.HasValue(message));
+        }
+
+        [Test]
+        public void HasValue_Proto2_Message()
+        {
+            var message = new Proto2.TestAllTypes();
+            var field = ((IMessage) message).Descriptor.Fields[Proto2.TestAllTypes.OptionalForeignMessageFieldNumber];
+            Assert.False(field.Accessor.HasValue(message));
+            message.OptionalForeignMessage = new Proto2.ForeignMessage();
+            Assert.True(field.Accessor.HasValue(message));
+            message.OptionalForeignMessage = null;
+            Assert.False(field.Accessor.HasValue(message));
+        }
+
+        [Test]
+        public void HasValue_Proto2_Oneof()
+        {
+            var message = new Proto2.TestAllTypes();
+            var accessor = ((IMessage) message).Descriptor.Fields[Proto2.TestAllTypes.OneofStringFieldNumber].Accessor;
+            Assert.False(accessor.HasValue(message));
+            // Even though it's the default value, we still have a value.
+            message.OneofString = "";
+            Assert.True(accessor.HasValue(message));
+            message.OneofString = "hello";
+            Assert.True(accessor.HasValue(message));
+            message.OneofUint32 = 10;
+            Assert.False(accessor.HasValue(message));
+        }
+
+        [Test]
+        public void HasValue_Proto2_Repeated()
+        {
+            var message = new Proto2.TestAllTypes();
+            var accessor = ((IMessage) message).Descriptor.Fields[Proto2.TestAllTypes.RepeatedBoolFieldNumber].Accessor;
+            Assert.Throws<InvalidOperationException>(() => accessor.HasValue(message));
+        }
+
+        [Test]
+        public void SetValue_SingleFields()
+        {
+            // Just a sample (primitives, messages, enums, strings, byte strings)
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var fields = TestProtos.TestAllTypes.Descriptor.Fields;
+            fields[TestProtos.TestAllTypes.SingleBoolFieldNumber].Accessor.SetValue(message, false);
+            fields[TestProtos.TestAllTypes.SingleInt32FieldNumber].Accessor.SetValue(message, 500);
+            fields[TestProtos.TestAllTypes.SingleStringFieldNumber].Accessor.SetValue(message, "It's a string");
+            fields[TestProtos.TestAllTypes.SingleBytesFieldNumber].Accessor.SetValue(message, ByteString.CopyFrom(99, 98, 97));
+            fields[TestProtos.TestAllTypes.SingleForeignEnumFieldNumber].Accessor.SetValue(message, ForeignEnum.ForeignFoo);
+            fields[TestProtos.TestAllTypes.SingleForeignMessageFieldNumber].Accessor.SetValue(message, new ForeignMessage { C = 12345 });
+            fields[TestProtos.TestAllTypes.SingleDoubleFieldNumber].Accessor.SetValue(message, 20150701.5);
+
+            var expected = new TestAllTypes(SampleMessages.CreateFullTestAllTypes())
+            {
+                SingleBool = false,
+                SingleInt32 = 500,
+                SingleString = "It's a string",
+                SingleBytes = ByteString.CopyFrom(99, 98, 97),
+                SingleForeignEnum = ForeignEnum.ForeignFoo,
+                SingleForeignMessage = new ForeignMessage { C = 12345 },
+                SingleDouble = 20150701.5
+            };
+
+            Assert.AreEqual(expected, message);
+        }
+
+        [Test]
+        public void SetValue_SingleFields_WrongType()
+        {
+            IMessage message = SampleMessages.CreateFullTestAllTypes();
+            var fields = message.Descriptor.Fields;
+            Assert.Throws<InvalidCastException>(() => fields[TestProtos.TestAllTypes.SingleBoolFieldNumber].Accessor.SetValue(message, "This isn't a bool"));
+        }
+
+        [Test]
+        public void SetValue_MapFields()
+        {
+            IMessage message = new TestMap();
+            var fields = message.Descriptor.Fields;
+            Assert.Throws<InvalidOperationException>(() => fields[TestMap.MapStringStringFieldNumber].Accessor.SetValue(message, new Dictionary<string, string>()));
+        }
+
+        [Test]
+        public void SetValue_RepeatedFields()
+        {
+            IMessage message = SampleMessages.CreateFullTestAllTypes();
+            var fields = message.Descriptor.Fields;
+            Assert.Throws<InvalidOperationException>(() => fields[TestProtos.TestAllTypes.RepeatedDoubleFieldNumber].Accessor.SetValue(message, new double[10]));
+        }
+
+        [Test]
+        public void Oneof()
+        {
+            var message = new TestAllTypes();
+            var descriptor = TestProtos.TestAllTypes.Descriptor;
+            Assert.AreEqual(1, descriptor.Oneofs.Count);
+            var oneof = descriptor.Oneofs[0];
+            Assert.AreEqual("oneof_field", oneof.Name);
+            Assert.IsNull(oneof.Accessor.GetCaseFieldDescriptor(message));
+
+            message.OneofString = "foo";
+            Assert.AreSame(descriptor.Fields[TestProtos.TestAllTypes.OneofStringFieldNumber], oneof.Accessor.GetCaseFieldDescriptor(message));
+
+            message.OneofUint32 = 10;
+            Assert.AreSame(descriptor.Fields[TestProtos.TestAllTypes.OneofUint32FieldNumber], oneof.Accessor.GetCaseFieldDescriptor(message));
+
+            oneof.Accessor.Clear(message);
+            Assert.AreEqual(TestProtos.TestAllTypes.OneofFieldOneofCase.None, message.OneofFieldCase);
+        }
+
+        [Test]
+        public void Clear()
+        {
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var fields = TestProtos.TestAllTypes.Descriptor.Fields;
+            fields[TestProtos.TestAllTypes.SingleBoolFieldNumber].Accessor.Clear(message);
+            fields[TestProtos.TestAllTypes.SingleInt32FieldNumber].Accessor.Clear(message);
+            fields[TestProtos.TestAllTypes.SingleStringFieldNumber].Accessor.Clear(message);
+            fields[TestProtos.TestAllTypes.SingleBytesFieldNumber].Accessor.Clear(message);
+            fields[TestProtos.TestAllTypes.SingleForeignEnumFieldNumber].Accessor.Clear(message);
+            fields[TestProtos.TestAllTypes.SingleForeignMessageFieldNumber].Accessor.Clear(message);
+            fields[TestProtos.TestAllTypes.RepeatedDoubleFieldNumber].Accessor.Clear(message);
+
+            var expected = new TestAllTypes(SampleMessages.CreateFullTestAllTypes())
+            {
+                SingleBool = false,
+                SingleInt32 = 0,
+                SingleString = "",
+                SingleBytes = ByteString.Empty,
+                SingleForeignEnum = 0,
+                SingleForeignMessage = null,
+            };
+            expected.RepeatedDouble.Clear();
+
+            Assert.AreEqual(expected, message);
+
+            // Separately, maps.
+            var mapMessage = new TestMap { MapStringString = { { "key1", "value1" }, { "key2", "value2" } } };
+            fields = TestMap.Descriptor.Fields;
+            fields[TestMap.MapStringStringFieldNumber].Accessor.Clear(mapMessage);
+            Assert.AreEqual(0, mapMessage.MapStringString.Count);
+        }
+
+        [Test]
+        public void Clear_Proto3Optional()
+        {
+            TestProto3Optional message = new TestProto3Optional
+            {
+                OptionalInt32 = 0,
+                OptionalNestedMessage = new TestProto3Optional.Types.NestedMessage()
+            };
+            var primitiveField = TestProto3Optional.Descriptor.Fields[TestProto3Optional.OptionalInt32FieldNumber];
+            var messageField = TestProto3Optional.Descriptor.Fields[TestProto3Optional.OptionalNestedMessageFieldNumber];
+
+            Assert.True(message.HasOptionalInt32);
+            Assert.NotNull(message.OptionalNestedMessage);
+
+            primitiveField.Accessor.Clear(message);
+            messageField.Accessor.Clear(message);
+
+            Assert.False(message.HasOptionalInt32);
+            Assert.Null(message.OptionalNestedMessage);
+        }
+
+        [Test]
+        public void Clear_Proto3_Oneof()
+        {
+            var message = new TestAllTypes();
+            var accessor = ((IMessage) message).Descriptor.Fields[TestProtos.TestAllTypes.OneofUint32FieldNumber].Accessor;
+
+            // The field accessor Clear method only affects a oneof if the current case is the one being cleared.
+            message.OneofString = "hello";
+            Assert.AreEqual(TestProtos.TestAllTypes.OneofFieldOneofCase.OneofString, message.OneofFieldCase);
+            accessor.Clear(message);
+            Assert.AreEqual(TestProtos.TestAllTypes.OneofFieldOneofCase.OneofString, message.OneofFieldCase);
+
+            message.OneofUint32 = 100;
+            Assert.AreEqual(TestProtos.TestAllTypes.OneofFieldOneofCase.OneofUint32, message.OneofFieldCase);
+            accessor.Clear(message);
+            Assert.AreEqual(TestProtos.TestAllTypes.OneofFieldOneofCase.None, message.OneofFieldCase);
+        }
+
+        [Test]
+        public void Clear_Proto2_Oneof()
+        {
+            var message = new Proto2.TestAllTypes();
+            var accessor = ((IMessage) message).Descriptor.Fields[Proto2.TestAllTypes.OneofUint32FieldNumber].Accessor;
+
+            // The field accessor Clear method only affects a oneof if the current case is the one being cleared.
+            message.OneofString = "hello";
+            Assert.AreEqual(Proto2.TestAllTypes.OneofFieldOneofCase.OneofString, message.OneofFieldCase);
+            accessor.Clear(message);
+            Assert.AreEqual(Proto2.TestAllTypes.OneofFieldOneofCase.OneofString, message.OneofFieldCase);
+
+            message.OneofUint32 = 100;
+            Assert.AreEqual(Proto2.TestAllTypes.OneofFieldOneofCase.OneofUint32, message.OneofFieldCase);
+            accessor.Clear(message);
+            Assert.AreEqual(Proto2.TestAllTypes.OneofFieldOneofCase.None, message.OneofFieldCase);
+        }
+
+        [Test]
+        public void FieldDescriptor_ByName()
+        {
+            var descriptor = TestProtos.TestAllTypes.Descriptor;
+            Assert.AreSame(
+                descriptor.Fields[TestProtos.TestAllTypes.SingleBoolFieldNumber],
+                descriptor.Fields["single_bool"]);
+        }
+
+        [Test]
+        public void FieldDescriptor_NotFound()
+        {
+            var descriptor = TestProtos.TestAllTypes.Descriptor;
+            Assert.Throws<KeyNotFoundException>(() => descriptor.Fields[999999].ToString());
+            Assert.Throws<KeyNotFoundException>(() => descriptor.Fields["not found"].ToString());
+        }
+
+        [Test]
+        public void GetExtensionValue()
+        {
+            var message = SampleMessages.CreateFullTestAllExtensions();
+
+            // test that the reflector works, since the reflector just runs through IExtendableMessage
+            Assert.AreEqual(message.GetExtension(OptionalBoolExtension), Proto2.TestAllExtensions.Descriptor.FindFieldByNumber(OptionalBoolExtension.FieldNumber).Accessor.GetValue(message));
+        }
+
+        [Test]
+        public void GetRepeatedExtensionValue()
+        {
+            // check to make sure repeated accessor uses GetOrRegister
+            var message = new Proto2.TestAllExtensions();
+
+            Assert.IsNull(message.GetExtension(RepeatedBoolExtension));
+            Assert.IsNotNull(Proto2.TestAllExtensions.Descriptor.FindFieldByNumber(RepeatedBoolExtension.FieldNumber).Accessor.GetValue(message));
+            Assert.IsNotNull(message.GetExtension(RepeatedBoolExtension));
+
+            message.ClearExtension(RepeatedBoolExtension);
+            Assert.IsNull(message.GetExtension(RepeatedBoolExtension));
+        }
+
+        [Test]
+        public void HasPresence()
+        {
+            // Proto3
+            var fields = TestProtos.TestAllTypes.Descriptor.Fields;
+            Assert.IsFalse(fields[TestProtos.TestAllTypes.SingleBoolFieldNumber].HasPresence);
+            Assert.IsTrue(fields[TestProtos.TestAllTypes.OneofBytesFieldNumber].HasPresence);
+            Assert.IsTrue(fields[TestProtos.TestAllTypes.SingleForeignMessageFieldNumber].HasPresence);
+            Assert.IsFalse(fields[TestProtos.TestAllTypes.RepeatedBoolFieldNumber].HasPresence);
+
+            fields = TestMap.Descriptor.Fields;
+            Assert.IsFalse(fields[TestMap.MapBoolBoolFieldNumber].HasPresence);
+
+            fields = TestProto3Optional.Descriptor.Fields;
+            Assert.IsTrue(fields[TestProto3Optional.OptionalBoolFieldNumber].HasPresence);
+
+            // Proto2
+            fields = Proto2.TestAllTypes.Descriptor.Fields;
+            Assert.IsTrue(fields[Proto2.TestAllTypes.OptionalBoolFieldNumber].HasPresence);
+            Assert.IsTrue(fields[Proto2.TestAllTypes.OneofBytesFieldNumber].HasPresence);
+            Assert.IsTrue(fields[Proto2.TestAllTypes.OptionalForeignMessageFieldNumber].HasPresence);
+            Assert.IsFalse(fields[Proto2.TestAllTypes.RepeatedBoolFieldNumber].HasPresence);
+
+            fields = Proto2.TestRequired.Descriptor.Fields;
+            Assert.IsTrue(fields[Proto2.TestRequired.AFieldNumber].HasPresence);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/Reflection/TypeRegistryTest.cs

@@ -0,0 +1,94 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using Google.Protobuf.TestProtos;
+using Google.Protobuf.WellKnownTypes;
+using NUnit.Framework;
+
+namespace Google.Protobuf.Reflection
+{
+    public class TypeRegistryTest
+    {
+        // Most of our tests use messages. Simple test that we really can use files...
+        [Test]
+        public void CreateWithFileDescriptor()
+        {
+            var registry = TypeRegistry.FromFiles(DurationReflection.Descriptor, StructReflection.Descriptor);
+            AssertDescriptorPresent(registry, Duration.Descriptor);
+            AssertDescriptorPresent(registry, ListValue.Descriptor);
+            AssertDescriptorAbsent(registry, Timestamp.Descriptor);
+        }
+
+        [Test]
+        public void TypesFromSameFile()
+        {
+            // Just for kicks, let's start with a nested type
+            var registry = TypeRegistry.FromMessages(TestAllTypes.Types.NestedMessage.Descriptor);
+            // Top-level...
+            AssertDescriptorPresent(registry, TestFieldOrderings.Descriptor);
+            // ... and nested (not the same as the original NestedMessage!)
+            AssertDescriptorPresent(registry, TestFieldOrderings.Types.NestedMessage.Descriptor);
+        }
+
+        [Test]
+        public void DependenciesAreIncluded()
+        {
+            var registry = TypeRegistry.FromMessages(TestAllTypes.Descriptor);
+            // Direct dependencies
+            AssertDescriptorPresent(registry, ImportMessage.Descriptor);
+            // Public dependencies
+            AssertDescriptorPresent(registry, PublicImportMessage.Descriptor);
+        }
+
+        [Test]
+        public void DuplicateFiles()
+        {
+            // Duplicates via dependencies and simply via repetition
+            var registry = TypeRegistry.FromFiles(
+                UnittestProto3Reflection.Descriptor, UnittestImportProto3Reflection.Descriptor,
+                TimestampReflection.Descriptor, TimestampReflection.Descriptor);
+            AssertDescriptorPresent(registry, TestAllTypes.Descriptor);
+            AssertDescriptorPresent(registry, ImportMessage.Descriptor);
+            AssertDescriptorPresent(registry, Timestamp.Descriptor);
+        }
+
+        private static void AssertDescriptorPresent(TypeRegistry registry, MessageDescriptor descriptor)
+        {
+            Assert.AreSame(descriptor, registry.Find(descriptor.FullName));
+        }
+
+        private static void AssertDescriptorAbsent(TypeRegistry registry, MessageDescriptor descriptor)
+        {
+            Assert.IsNull(registry.Find(descriptor.FullName));
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/SampleEnum.cs

@@ -0,0 +1,42 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+namespace Google.Protobuf
+{
+    // Just a sample enum with positive and negative values to be used in tests.
+    internal enum SampleEnum
+    {
+        NegativeValue = -2,
+        None = 0,
+        PositiveValue = 3
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/SampleMessages.cs

@@ -0,0 +1,207 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using Google.Protobuf.TestProtos;
+using Proto2 = Google.Protobuf.TestProtos.Proto2;
+
+using static Google.Protobuf.TestProtos.Proto2.UnittestExtensions;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Helper methods to create sample instances of types generated from unit test messages.
+    /// </summary>
+    public class SampleMessages
+    {
+        /// <summary>
+        /// Creates a new sample TestAllTypes message with all fields populated.
+        /// The "oneof" field is populated with the string property (OneofString).
+        /// </summary>
+        public static TestAllTypes CreateFullTestAllTypes()
+        {
+            return new TestAllTypes
+            {
+                SingleBool = true,
+                SingleBytes = ByteString.CopyFrom(1, 2, 3, 4),
+                SingleDouble = 23.5,
+                SingleFixed32 = 23,
+                SingleFixed64 = 1234567890123,
+                SingleFloat = 12.25f,
+                SingleForeignEnum = ForeignEnum.ForeignBar,
+                SingleForeignMessage = new ForeignMessage { C = 10 },
+                SingleImportEnum = ImportEnum.ImportBaz,
+                SingleImportMessage = new ImportMessage { D = 20 },
+                SingleInt32 = 100,
+                SingleInt64 = 3210987654321,
+                SingleNestedEnum = TestProtos.TestAllTypes.Types.NestedEnum.Foo,
+                SingleNestedMessage = new TestAllTypes.Types.NestedMessage { Bb = 35 },
+                SinglePublicImportMessage = new PublicImportMessage { E = 54 },
+                SingleSfixed32 = -123,
+                SingleSfixed64 = -12345678901234,
+                SingleSint32 = -456,
+                SingleSint64 = -12345678901235,
+                SingleString = "test",
+                SingleUint32 = UInt32.MaxValue,
+                SingleUint64 = UInt64.MaxValue,
+                RepeatedBool = { true, false },
+                RepeatedBytes = { ByteString.CopyFrom(1, 2, 3, 4), ByteString.CopyFrom(5, 6), ByteString.CopyFrom(new byte[1000]) },
+                RepeatedDouble = { -12.25, 23.5 },
+                RepeatedFixed32 = { UInt32.MaxValue, 23 },
+                RepeatedFixed64 = { UInt64.MaxValue, 1234567890123 },
+                RepeatedFloat = { 100f, 12.25f },
+                RepeatedForeignEnum = { ForeignEnum.ForeignFoo, ForeignEnum.ForeignBar },
+                RepeatedForeignMessage = { new ForeignMessage(), new ForeignMessage { C = 10 } },
+                RepeatedImportEnum = { ImportEnum.ImportBaz, ImportEnum.Unspecified },
+                RepeatedImportMessage = { new ImportMessage { D = 20 }, new ImportMessage { D = 25 } },
+                RepeatedInt32 = { 100, 200 },
+                RepeatedInt64 = { 3210987654321, Int64.MaxValue },
+                RepeatedNestedEnum = { TestProtos.TestAllTypes.Types.NestedEnum.Foo, TestProtos.TestAllTypes.Types.NestedEnum.Neg },
+                RepeatedNestedMessage = { new TestAllTypes.Types.NestedMessage { Bb = 35 }, new TestAllTypes.Types.NestedMessage { Bb = 10 } },
+                RepeatedPublicImportMessage = { new PublicImportMessage { E = 54 }, new PublicImportMessage { E = -1 } },
+                RepeatedSfixed32 = { -123, 123 },
+                RepeatedSfixed64 = { -12345678901234, 12345678901234 },
+                RepeatedSint32 = { -456, 100 },
+                RepeatedSint64 = { -12345678901235, 123 },
+                RepeatedString = { "foo", "bar" },
+                RepeatedUint32 = { UInt32.MaxValue, UInt32.MinValue },
+                RepeatedUint64 = { UInt64.MaxValue, UInt32.MinValue },
+                OneofString = "Oneof string"
+            };
+        }
+
+        public static Proto2.TestAllTypes CreateFullTestAllTypesProto2()
+        {
+            return new Proto2.TestAllTypes
+            {
+                OptionalBool = true,
+                OptionalBytes = ByteString.CopyFrom(1, 2, 3, 4),
+                OptionalDouble = 23.5,
+                OptionalFixed32 = 23,
+                OptionalFixed64 = 1234567890123,
+                OptionalFloat = 12.25f,
+                OptionalForeignEnum = Proto2.ForeignEnum.ForeignBar,
+                OptionalForeignMessage = new Proto2.ForeignMessage { C = 10 },
+                OptionalImportEnum = Proto2.ImportEnum.ImportBaz,
+                OptionalImportMessage = new Proto2.ImportMessage { D = 20 },
+                OptionalInt32 = 100,
+                OptionalInt64 = 3210987654321,
+                OptionalNestedEnum = Proto2.TestAllTypes.Types.NestedEnum.Foo,
+                OptionalNestedMessage = new Proto2.TestAllTypes.Types.NestedMessage { Bb = 35 },
+                OptionalPublicImportMessage = new Proto2.PublicImportMessage { E = 54 },
+                OptionalSfixed32 = -123,
+                OptionalSfixed64 = -12345678901234,
+                OptionalSint32 = -456,
+                OptionalSint64 = -12345678901235,
+                OptionalString = "test",
+                OptionalUint32 = UInt32.MaxValue,
+                OptionalUint64 = UInt64.MaxValue,
+                OptionalGroup = new Proto2.TestAllTypes.Types.OptionalGroup { A = 10 },
+                RepeatedBool = { true, false },
+                RepeatedBytes = { ByteString.CopyFrom(1, 2, 3, 4), ByteString.CopyFrom(5, 6), ByteString.CopyFrom(new byte[1000]) },
+                RepeatedDouble = { -12.25, 23.5 },
+                RepeatedFixed32 = { UInt32.MaxValue, 23 },
+                RepeatedFixed64 = { UInt64.MaxValue, 1234567890123 },
+                RepeatedFloat = { 100f, 12.25f },
+                RepeatedForeignEnum = { Proto2.ForeignEnum.ForeignFoo, Proto2.ForeignEnum.ForeignBar },
+                RepeatedForeignMessage = { new Proto2.ForeignMessage(), new Proto2.ForeignMessage { C = 10 } },
+                RepeatedImportEnum = { Proto2.ImportEnum.ImportBaz, Proto2.ImportEnum.ImportFoo },
+                RepeatedImportMessage = { new Proto2.ImportMessage { D = 20 }, new Proto2.ImportMessage { D = 25 } },
+                RepeatedInt32 = { 100, 200 },
+                RepeatedInt64 = { 3210987654321, Int64.MaxValue },
+                RepeatedNestedEnum = { Proto2.TestAllTypes.Types.NestedEnum.Foo, Proto2.TestAllTypes.Types.NestedEnum.Neg },
+                RepeatedNestedMessage = { new Proto2.TestAllTypes.Types.NestedMessage { Bb = 35 }, new Proto2.TestAllTypes.Types.NestedMessage { Bb = 10 } },
+                RepeatedSfixed32 = { -123, 123 },
+                RepeatedSfixed64 = { -12345678901234, 12345678901234 },
+                RepeatedSint32 = { -456, 100 },
+                RepeatedSint64 = { -12345678901235, 123 },
+                RepeatedString = { "foo", "bar" },
+                RepeatedUint32 = { UInt32.MaxValue, UInt32.MinValue },
+                RepeatedUint64 = { UInt64.MaxValue, UInt32.MinValue },
+                RepeatedGroup = { new Proto2.TestAllTypes.Types.RepeatedGroup { A = 10 }, new Proto2.TestAllTypes.Types.RepeatedGroup { A = 20 } },
+                OneofString = "Oneof string"
+            };
+        }
+
+        public static Proto2.TestAllExtensions CreateFullTestAllExtensions()
+        {
+            var message = new Proto2.TestAllExtensions();
+            message.SetExtension(OptionalBoolExtension, true);
+            message.SetExtension(OptionalBytesExtension, ByteString.CopyFrom(1, 2, 3, 4));
+            message.SetExtension(OptionalDoubleExtension, 23.5);
+            message.SetExtension(OptionalFixed32Extension, 23u);
+            message.SetExtension(OptionalFixed64Extension, 1234567890123u);
+            message.SetExtension(OptionalFloatExtension, 12.25f);
+            message.SetExtension(OptionalForeignEnumExtension, Proto2.ForeignEnum.ForeignBar);
+            message.SetExtension(OptionalForeignMessageExtension, new Proto2.ForeignMessage { C = 10 });
+            message.SetExtension(OptionalImportEnumExtension, Proto2.ImportEnum.ImportBaz);
+            message.SetExtension(OptionalImportMessageExtension, new Proto2.ImportMessage { D = 20 });
+            message.SetExtension(OptionalInt32Extension, 100);
+            message.SetExtension(OptionalInt64Extension, 3210987654321);
+            message.SetExtension(OptionalNestedEnumExtension, Proto2.TestAllTypes.Types.NestedEnum.Foo);
+            message.SetExtension(OptionalNestedMessageExtension, new Proto2.TestAllTypes.Types.NestedMessage { Bb = 35 });
+            message.SetExtension(OptionalPublicImportMessageExtension, new Proto2.PublicImportMessage { E = 54 });
+            message.SetExtension(OptionalSfixed32Extension, -123);
+            message.SetExtension(OptionalSfixed64Extension, -12345678901234);
+            message.SetExtension(OptionalSint32Extension, -456);
+            message.SetExtension(OptionalSint64Extension, -12345678901235);
+            message.SetExtension(OptionalStringExtension, "test");
+            message.SetExtension(OptionalUint32Extension, UInt32.MaxValue);
+            message.SetExtension(OptionalUint64Extension, UInt64.MaxValue);
+            message.SetExtension(OptionalGroupExtension, new Proto2.OptionalGroup_extension { A = 10 });
+            message.GetOrInitializeExtension(RepeatedBoolExtension).AddRange(new[] { true, false });
+            message.GetOrInitializeExtension(RepeatedBytesExtension).AddRange(new[] { ByteString.CopyFrom(1, 2, 3, 4), ByteString.CopyFrom(5, 6), ByteString.CopyFrom(new byte[1000]) });
+            message.GetOrInitializeExtension(RepeatedDoubleExtension).AddRange(new[] { -12.25, 23.5 });
+            message.GetOrInitializeExtension(RepeatedFixed32Extension).AddRange(new[] { UInt32.MaxValue, 23u });
+            message.GetOrInitializeExtension(RepeatedFixed64Extension).AddRange(new[] { UInt64.MaxValue, 1234567890123ul });
+            message.GetOrInitializeExtension(RepeatedFloatExtension).AddRange(new[] { 100f, 12.25f });
+            message.GetOrInitializeExtension(RepeatedForeignEnumExtension).AddRange(new[] { Proto2.ForeignEnum.ForeignFoo, Proto2.ForeignEnum.ForeignBar });
+            message.GetOrInitializeExtension(RepeatedForeignMessageExtension).AddRange(new[] { new Proto2.ForeignMessage(), new Proto2.ForeignMessage { C = 10 } });
+            message.GetOrInitializeExtension(RepeatedImportEnumExtension).AddRange(new[] { Proto2.ImportEnum.ImportBaz, Proto2.ImportEnum.ImportFoo });
+            message.GetOrInitializeExtension(RepeatedImportMessageExtension).AddRange(new[] { new Proto2.ImportMessage { D = 20 }, new Proto2.ImportMessage { D = 25 } });
+            message.GetOrInitializeExtension(RepeatedInt32Extension).AddRange(new[] { 100, 200 });
+            message.GetOrInitializeExtension(RepeatedInt64Extension).AddRange(new[] { 3210987654321, Int64.MaxValue });
+            message.GetOrInitializeExtension(RepeatedNestedEnumExtension).AddRange(new[] { Proto2.TestAllTypes.Types.NestedEnum.Foo, Proto2.TestAllTypes.Types.NestedEnum.Neg });
+            message.GetOrInitializeExtension(RepeatedNestedMessageExtension).AddRange(new[] { new Proto2.TestAllTypes.Types.NestedMessage { Bb = 35 }, new Proto2.TestAllTypes.Types.NestedMessage { Bb = 10 } });
+            message.GetOrInitializeExtension(RepeatedSfixed32Extension).AddRange(new[] { -123, 123 });
+            message.GetOrInitializeExtension(RepeatedSfixed64Extension).AddRange(new[] { -12345678901234, 12345678901234 });
+            message.GetOrInitializeExtension(RepeatedSint32Extension).AddRange(new[] { -456, 100 });
+            message.GetOrInitializeExtension(RepeatedSint64Extension).AddRange(new[] { -12345678901235, 123 });
+            message.GetOrInitializeExtension(RepeatedStringExtension).AddRange(new[] { "foo", "bar" });
+            message.GetOrInitializeExtension(RepeatedUint32Extension).AddRange(new[] { UInt32.MaxValue, UInt32.MinValue });
+            message.GetOrInitializeExtension(RepeatedUint64Extension).AddRange(new[] { UInt64.MaxValue, UInt32.MinValue });
+            message.GetOrInitializeExtension(RepeatedGroupExtension).AddRange(new[] { new Proto2.RepeatedGroup_extension { A = 10 }, new Proto2.RepeatedGroup_extension { A = 20 } });
+            message.SetExtension(OneofStringExtension, "Oneof string");
+            return message;
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/SampleNaNs.cs

@@ -0,0 +1,53 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2017 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Samples of different not-a-number values, for testing equality comparisons.
+    /// </summary>
+    public static class SampleNaNs
+    {
+        public static double Regular { get; } = double.NaN;
+
+        // Signalling bit is inverted compared with double.NaN. Doesn't really matter
+        // whether that makes it quiet or signalling - it's different.
+        public static double SignallingFlipped { get; } =
+            BitConverter.Int64BitsToDouble(BitConverter.DoubleToInt64Bits(double.NaN) ^ -0x8000_0000_0000_0000L);
+
+        // A bit in the middle of the mantissa is flipped; this difference is preserved when casting to float.
+        public static double PayloadFlipped { get; } =
+            BitConverter.Int64BitsToDouble(BitConverter.DoubleToInt64Bits(double.NaN) ^ 0x1_0000_0000L);
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/TestCornerCases.cs

@@ -0,0 +1,62 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+    
+using UnitTest.Issues.TestProtos;
+using NUnit.Framework;
+
+namespace Google.Protobuf
+{
+    public class TestCornerCases
+    {
+        [Test]
+        public void TestRoundTripNegativeEnums()
+        {
+            NegativeEnumMessage msg = new NegativeEnumMessage
+            {
+                Value = NegativeEnum.MinusOne,
+                Values = { NegativeEnum.Zero, NegativeEnum.MinusOne, NegativeEnum.FiveBelow },
+                PackedValues = { NegativeEnum.Zero, NegativeEnum.MinusOne, NegativeEnum.FiveBelow }
+            };
+
+            Assert.AreEqual(58, msg.CalculateSize());
+
+            byte[] bytes = new byte[58];
+            CodedOutputStream output = new CodedOutputStream(bytes);
+
+            msg.WriteTo(output);
+            Assert.AreEqual(0, output.SpaceLeft);
+
+            NegativeEnumMessage copy = NegativeEnumMessage.Parser.ParseFrom(bytes);
+            Assert.AreEqual(msg, copy);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/UnknownFieldSetTest.cs

@@ -0,0 +1,226 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System.IO;
+using Google.Protobuf.TestProtos;
+using NUnit.Framework;
+
+namespace Google.Protobuf
+{
+    public class UnknownFieldSetTest
+    {
+        public class Data
+        {
+            public static System.Collections.IEnumerable Messages
+            {
+                get
+                {
+                    yield return SampleMessages.CreateFullTestAllTypesProto2();
+                    yield return SampleMessages.CreateFullTestAllTypes();
+                }
+            }
+        }
+
+        [Test]
+        public void EmptyUnknownFieldSet()
+        {
+            UnknownFieldSet unknownFields = new UnknownFieldSet();
+            Assert.AreEqual(0, unknownFields.CalculateSize());
+        }
+
+        [Test]
+        public void MergeUnknownFieldSet()
+        {
+            UnknownFieldSet unknownFields = new UnknownFieldSet();
+            UnknownField field = new UnknownField();
+            field.AddFixed32(123);
+            unknownFields.AddOrReplaceField(1, field);
+            UnknownFieldSet otherUnknownFields = new UnknownFieldSet();
+            Assert.IsFalse(otherUnknownFields.HasField(1));
+            UnknownFieldSet.MergeFrom(otherUnknownFields, unknownFields);
+            Assert.IsTrue(otherUnknownFields.HasField(1));
+        }
+
+        [Test]
+        [TestCaseSource(typeof(Data), "Messages")]
+        public void TestMergeCodedInput(IMessage message)
+        {
+            var emptyMessage = new TestEmptyMessage();
+            emptyMessage.MergeFrom(message.ToByteArray());
+            Assert.AreEqual(message.CalculateSize(), emptyMessage.CalculateSize());
+            Assert.AreEqual(message.ToByteArray(), emptyMessage.ToByteArray());
+
+            var newMessage = message.Descriptor.Parser.ParseFrom(emptyMessage.ToByteArray());
+            Assert.AreEqual(message, newMessage);
+            Assert.AreEqual(message.CalculateSize(), newMessage.CalculateSize());
+        }
+
+        [Test]
+        [TestCaseSource(typeof(Data), "Messages")]
+        public void TestMergeMessage(IMessage message)
+        {
+            var emptyMessage = new TestEmptyMessage();
+            var otherEmptyMessage = new TestEmptyMessage();
+            emptyMessage.MergeFrom(message.ToByteArray());
+            otherEmptyMessage.MergeFrom(emptyMessage);
+
+            Assert.AreEqual(message.CalculateSize(), otherEmptyMessage.CalculateSize());
+            Assert.AreEqual(message.ToByteArray(), otherEmptyMessage.ToByteArray());
+        }
+
+        [Test]
+        [TestCaseSource(typeof(Data), "Messages")]
+        public void TestEquals(IMessage message)
+        {
+            var emptyMessage = new TestEmptyMessage();
+            var otherEmptyMessage = new TestEmptyMessage();
+            Assert.AreEqual(emptyMessage, otherEmptyMessage);
+            emptyMessage.MergeFrom(message.ToByteArray());
+            Assert.AreNotEqual(emptyMessage.CalculateSize(),
+                               otherEmptyMessage.CalculateSize());
+            Assert.AreNotEqual(emptyMessage, otherEmptyMessage);
+        }
+
+        [Test]
+        [TestCaseSource(typeof(Data), "Messages")]
+        public void TestHashCode(IMessage message)
+        {
+            var emptyMessage = new TestEmptyMessage();
+            int hashCode = emptyMessage.GetHashCode();
+            emptyMessage.MergeFrom(message.ToByteArray());
+            Assert.AreNotEqual(hashCode, emptyMessage.GetHashCode());
+        }
+
+        [Test]
+        [TestCaseSource(typeof(Data), "Messages")]
+        public void TestClone(IMessage message)
+        {
+            var emptyMessage = new TestEmptyMessage();
+            TestEmptyMessage otherEmptyMessage = emptyMessage.Clone();
+            Assert.AreEqual(emptyMessage.CalculateSize(), otherEmptyMessage.CalculateSize());
+            Assert.AreEqual(emptyMessage.ToByteArray(), otherEmptyMessage.ToByteArray());
+
+            emptyMessage.MergeFrom(message.ToByteArray());
+            otherEmptyMessage = emptyMessage.Clone();
+            Assert.AreEqual(message.CalculateSize(), otherEmptyMessage.CalculateSize());
+            Assert.AreEqual(message.ToByteArray(), otherEmptyMessage.ToByteArray());
+        }
+
+        [Test]
+        public void TestClone_LengthDelimited()
+        {
+            var unknownVarintField = new UnknownField();
+            unknownVarintField.AddVarint(99);
+
+            var unknownLengthDelimitedField1 = new UnknownField();
+            unknownLengthDelimitedField1.AddLengthDelimited(ByteString.CopyFromUtf8("some data"));
+
+            var unknownLengthDelimitedField2 = new UnknownField();
+            unknownLengthDelimitedField2.AddLengthDelimited(ByteString.CopyFromUtf8("some more data"));
+
+            var destUnknownFieldSet = new UnknownFieldSet();
+            destUnknownFieldSet.AddOrReplaceField(997, unknownVarintField);
+            destUnknownFieldSet.AddOrReplaceField(999, unknownLengthDelimitedField1);
+            destUnknownFieldSet.AddOrReplaceField(999, unknownLengthDelimitedField2);
+
+            var clone = UnknownFieldSet.Clone(destUnknownFieldSet);
+
+            Assert.IsTrue(clone.HasField(997));
+            Assert.IsTrue(clone.HasField(999));
+        }
+
+        [Test]
+        [TestCaseSource(typeof(Data), "Messages")]
+        public void TestDiscardUnknownFields(IMessage message)
+        {
+            var goldenEmptyMessage = new TestEmptyMessage();
+            byte[] data = message.ToByteArray();
+            int fullSize = message.CalculateSize();
+
+            void AssertEmpty(IMessage msg)
+            {
+                Assert.AreEqual(0, msg.CalculateSize());
+                Assert.AreEqual(goldenEmptyMessage, msg);
+            }
+
+            void AssertFull(IMessage msg) => Assert.AreEqual(fullSize, msg.CalculateSize());
+
+            // Test the behavior of the parsers with and without discarding, both generic and non-generic.
+            MessageParser<TestEmptyMessage> retainingParser1 = TestEmptyMessage.Parser;
+            MessageParser retainingParser2 = retainingParser1;
+            MessageParser<TestEmptyMessage> discardingParser1 = retainingParser1.WithDiscardUnknownFields(true);
+            MessageParser discardingParser2 = retainingParser2.WithDiscardUnknownFields(true);
+
+            // Test parse from byte[]
+            MessageParsingHelpers.AssertReadingMessage(retainingParser1, data, m => AssertFull(m));
+            MessageParsingHelpers.AssertReadingMessage(retainingParser2, data, m => AssertFull(m));
+            MessageParsingHelpers.AssertReadingMessage(discardingParser1, data, m => AssertEmpty(m));
+            MessageParsingHelpers.AssertReadingMessage(discardingParser2, data, m => AssertEmpty(m));
+
+            // Test parse from byte[] with offset
+            AssertFull(retainingParser1.ParseFrom(data, 0, data.Length));
+            AssertFull(retainingParser2.ParseFrom(data, 0, data.Length));
+            AssertEmpty(discardingParser1.ParseFrom(data, 0, data.Length));
+            AssertEmpty(discardingParser2.ParseFrom(data, 0, data.Length));
+
+            // Test parse from CodedInputStream
+            AssertFull(retainingParser1.ParseFrom(new CodedInputStream(data)));
+            AssertFull(retainingParser2.ParseFrom(new CodedInputStream(data)));
+            AssertEmpty(discardingParser1.ParseFrom(new CodedInputStream(data)));
+            AssertEmpty(discardingParser2.ParseFrom(new CodedInputStream(data)));
+
+            // Test parse from Stream
+            AssertFull(retainingParser1.ParseFrom(new MemoryStream(data)));
+            AssertFull(retainingParser2.ParseFrom(new MemoryStream(data)));
+            AssertEmpty(discardingParser1.ParseFrom(new MemoryStream(data)));
+            AssertEmpty(discardingParser2.ParseFrom(new MemoryStream(data)));
+        }
+
+        [Test]
+        public void TestReadInvalidWireTypeThrowsInvalidProtocolBufferException()
+        {
+            MemoryStream ms = new MemoryStream();
+            CodedOutputStream output = new CodedOutputStream(ms);
+
+            uint tag = WireFormat.MakeTag(1, (WireFormat.WireType)6);
+            output.WriteRawVarint32(tag);
+            output.WriteLength(-1);
+            output.Flush();
+            ms.Position = 0;
+
+            CodedInputStream input = new CodedInputStream(ms);
+            Assert.AreEqual(tag, input.ReadTag());
+
+            Assert.Throws<InvalidProtocolBufferException>(() => UnknownFieldSet.MergeFieldFrom(null, input));
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/WellKnownTypes/AnyTest.cs

@@ -0,0 +1,183 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using Google.Protobuf.Reflection;
+using Google.Protobuf.TestProtos;
+using NUnit.Framework;
+using System.Linq;
+using UnitTest.Issues.TestProtos;
+
+namespace Google.Protobuf.WellKnownTypes
+{
+    public class AnyTest
+    {
+        [Test]
+        public void Pack()
+        {
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var any = Any.Pack(message);
+            Assert.AreEqual("type.googleapis.com/protobuf_unittest3.TestAllTypes", any.TypeUrl);
+            Assert.AreEqual(message.CalculateSize(), any.Value.Length);
+        }
+
+        [Test]
+        public void Pack_WithCustomPrefix()
+        {
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var any = Any.Pack(message, "foo.bar/baz");
+            Assert.AreEqual("foo.bar/baz/protobuf_unittest3.TestAllTypes", any.TypeUrl);
+            Assert.AreEqual(message.CalculateSize(), any.Value.Length);
+        }
+
+        [Test]
+        public void Pack_WithCustomPrefixTrailingSlash()
+        {
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var any = Any.Pack(message, "foo.bar/baz/");
+            Assert.AreEqual("foo.bar/baz/protobuf_unittest3.TestAllTypes", any.TypeUrl);
+            Assert.AreEqual(message.CalculateSize(), any.Value.Length);
+        }
+
+        [Test]
+        public void Unpack_WrongType()
+        {
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var any = Any.Pack(message);
+            Assert.Throws<InvalidProtocolBufferException>(() => any.Unpack<TestOneof>());
+        }
+
+        [Test]
+        public void Unpack_Success()
+        {
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var any = Any.Pack(message);
+            var unpacked = any.Unpack<TestAllTypes>();
+            Assert.AreEqual(message, unpacked);
+        }
+
+        [Test]
+        public void Unpack_CustomPrefix_Success()
+        {
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var any = Any.Pack(message, "foo.bar/baz");
+            var unpacked = any.Unpack<TestAllTypes>();
+            Assert.AreEqual(message, unpacked);
+        }
+
+        [Test]
+        public void TryUnpack_WrongType()
+        {
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var any = Any.Pack(message);
+            Assert.False(any.TryUnpack(out TestOneof unpacked));
+            Assert.Null(unpacked);
+        }
+
+        [Test]
+        public void TryUnpack_RightType()
+        {
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var any = Any.Pack(message);
+            Assert.IsTrue(any.TryUnpack(out TestAllTypes unpacked));
+            Assert.AreEqual(message, unpacked);
+        }
+
+        [Test]
+        public void ToString_WithValues()
+        {
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var any = Any.Pack(message);
+            var text = any.ToString();
+            Assert.That(text, Does.Contain("\"@value\": \"" + message.ToByteString().ToBase64() + "\""));
+        }
+
+        [Test]
+        [TestCase("proto://foo.bar", "foo.bar")]
+        [TestCase("/foo/bar/baz", "baz")]
+        [TestCase("foobar", "")]
+        public void GetTypeName(string typeUrl, string expectedTypeName)
+        {
+            Assert.AreEqual(expectedTypeName, Any.GetTypeName(typeUrl));
+        }
+
+        [Test]
+        public void ToString_Empty()
+        {
+            var any = new Any();
+            Assert.AreEqual("{ \"@type\": \"\", \"@value\": \"\" }", any.ToString());
+        }
+
+        [Test]
+        public void ToString_MessageContainingAny()
+        {
+            var message = new TestWellKnownTypes { AnyField = new Any() };
+            Assert.AreEqual("{ \"anyField\": { \"@type\": \"\", \"@value\": \"\" } }", message.ToString());
+        }
+
+        [Test]
+        public void IsWrongType()
+        {
+            var any = Any.Pack(SampleMessages.CreateFullTestAllTypes());
+            Assert.False(any.Is(TestOneof.Descriptor));
+        }
+
+        [Test]
+        public void IsRightType()
+        {
+            var any = Any.Pack(SampleMessages.CreateFullTestAllTypes());
+            Assert.True(any.Is(TestAllTypes.Descriptor));
+        }
+
+        [Test]
+        public void Unpack_TypeRegistry()
+        {
+            var messages = new IMessage[]
+            {
+                SampleMessages.CreateFullTestAllTypes(),
+                new TestWellKnownTypes { BoolField = true },
+                new MoreString { Data = { "x" } },
+                new MoreBytes { Data = ByteString.CopyFromUtf8("xyz") },
+                new ReservedNames { Descriptor_ = 10 }
+            };
+            var anyMessages = messages.Select(Any.Pack);
+
+            // The type registry handles the first four of the packed messages, but not the final one.
+            var registry = TypeRegistry.FromFiles(
+                UnittestWellKnownTypesReflection.Descriptor,
+                UnittestProto3Reflection.Descriptor);
+            var unpacked = anyMessages.Select(any => any.Unpack(registry)).ToList();
+            var expected = (IMessage[]) messages.Clone();
+            expected[4] = null;
+            Assert.AreEqual(expected, unpacked);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/WellKnownTypes/DurationTest.cs

@@ -0,0 +1,165 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using NUnit.Framework;
+using System;
+
+namespace Google.Protobuf.WellKnownTypes
+{
+    public class DurationTest
+    {
+        [Test]
+        public void ToTimeSpan()
+        {
+            Assert.AreEqual(TimeSpan.FromSeconds(1), new Duration { Seconds = 1 }.ToTimeSpan());
+            Assert.AreEqual(TimeSpan.FromSeconds(-1), new Duration { Seconds = -1 }.ToTimeSpan());
+            Assert.AreEqual(TimeSpan.FromMilliseconds(1), new Duration { Nanos = 1000000 }.ToTimeSpan());
+            Assert.AreEqual(TimeSpan.FromMilliseconds(-1), new Duration { Nanos = -1000000 }.ToTimeSpan());
+            Assert.AreEqual(TimeSpan.FromTicks(1), new Duration { Nanos = 100 }.ToTimeSpan());
+            Assert.AreEqual(TimeSpan.FromTicks(-1), new Duration { Nanos = -100 }.ToTimeSpan());
+
+            // Rounding is towards 0
+            Assert.AreEqual(TimeSpan.FromTicks(2), new Duration { Nanos = 250 }.ToTimeSpan());
+            Assert.AreEqual(TimeSpan.FromTicks(-2), new Duration { Nanos = -250 }.ToTimeSpan());
+        }
+
+        [Test]
+        public void Addition()
+        {
+            Assert.AreEqual(new Duration { Seconds = 2, Nanos = 100000000 },
+                new Duration { Seconds = 1, Nanos = 600000000 } + new Duration { Nanos = 500000000 });
+            Assert.AreEqual(new Duration { Seconds = -2, Nanos = -100000000 },
+                new Duration { Seconds = -1, Nanos = -600000000 } + new Duration { Nanos = -500000000 });
+            Assert.AreEqual(new Duration { Seconds = 1, Nanos = 100000000 },
+                new Duration { Seconds = 1, Nanos = 600000000 } + new Duration { Nanos = -500000000 });
+
+            // Non-normalized durations, or non-normalized intermediate results
+            Assert.AreEqual(new Duration { Seconds = 1 },
+                new Duration { Seconds = 1, Nanos = -500000000 } + new Duration { Nanos = 500000000 });
+
+            Assert.AreEqual(new Duration { Nanos = -900000000 },
+                new Duration { Seconds = -1, Nanos = -100000000 } + new Duration { Nanos = 200000000 });
+            Assert.AreEqual(new Duration { Nanos = 900000000 },
+                new Duration { Seconds = 1, Nanos = 100000000 } + new Duration { Nanos = -200000000 });
+        }
+
+        [Test]
+        public void Subtraction()
+        {
+            Assert.AreEqual(new Duration { Seconds = 1, Nanos = 100000000 },
+                new Duration { Seconds = 1, Nanos = 600000000 } - new Duration { Nanos = 500000000 });
+            Assert.AreEqual(new Duration { Seconds = -1, Nanos = -100000000 },
+                new Duration { Seconds = -1, Nanos = -600000000 } - new Duration { Nanos = -500000000 });
+            Assert.AreEqual(new Duration { Seconds = 2, Nanos = 100000000 },
+                new Duration { Seconds = 1, Nanos = 600000000 } - new Duration { Nanos = -500000000 });
+
+            // Non-normalized durations
+            Assert.AreEqual(new Duration(),
+                new Duration { Seconds = 1, Nanos = -500000000 } - new Duration { Nanos = 500000000 });
+            Assert.AreEqual(new Duration { Seconds = 1 },
+                new Duration { Nanos = 2000000000 } - new Duration { Nanos = 1000000000 });
+        }
+
+        [Test]
+        public void FromTimeSpan()
+        {
+            Assert.AreEqual(new Duration { Seconds = 1 }, Duration.FromTimeSpan(TimeSpan.FromSeconds(1)));
+            Assert.AreEqual(new Duration { Nanos = Duration.NanosecondsPerTick }, Duration.FromTimeSpan(TimeSpan.FromTicks(1)));
+        }
+
+        [Test]
+        [TestCase(0, Duration.MaxNanoseconds + 1)]
+        [TestCase(0, Duration.MinNanoseconds - 1)]
+        [TestCase(Duration.MinSeconds - 1, 0)]
+        [TestCase(Duration.MaxSeconds + 1, 0)]
+        [TestCase(1, -1)]
+        [TestCase(-1, 1)]
+        public void ToTimeSpan_Invalid(long seconds, int nanoseconds)
+        {
+            var duration = new Duration { Seconds = seconds, Nanos = nanoseconds };
+            Assert.Throws<InvalidOperationException>(() => duration.ToTimeSpan());
+        }
+
+        [Test]
+        [TestCase(0, Duration.MaxNanoseconds)]
+        [TestCase(0, Duration.MinNanoseconds)]
+        [TestCase(Duration.MinSeconds, Duration.MinNanoseconds)]
+        [TestCase(Duration.MaxSeconds, Duration.MaxNanoseconds)]
+        public void ToTimeSpan_Valid(long seconds, int nanoseconds)
+        {
+            // Only testing that these values don't throw, unlike their similar tests in ToTimeSpan_Invalid
+            var duration = new Duration { Seconds = seconds, Nanos = nanoseconds };
+            duration.ToTimeSpan();
+        }
+
+        [Test]
+        public void ToString_NonNormalized()
+        {
+            // Just a single example should be sufficient...
+            var duration = new Duration { Seconds = 1, Nanos = -1 };
+            Assert.AreEqual("{ \"@warning\": \"Invalid Duration\", \"seconds\": \"1\", \"nanos\": -1 }", duration.ToString());
+        }
+
+        [Test]
+        public void Comparability()
+        {
+            Duration[] durationsInExpectedSortOrder =
+            {
+                null,
+                new Duration { Seconds = -10, Nanos = -10 },
+                new Duration { Seconds = -10, Nanos = -1 },
+                new Duration { Seconds = -1, Nanos = -10 },
+                new Duration { Seconds = -1, Nanos = -1 },
+                new Duration(),
+                new Duration { Seconds = 1, Nanos = 1 },
+                new Duration { Seconds = 1, Nanos = 10 },
+                new Duration { Seconds = 10, Nanos = 1 },
+                new Duration { Seconds = 10, Nanos = 10 }
+            };
+
+            for (int i = 0; i < durationsInExpectedSortOrder.Length; i++)
+            {
+                var target = durationsInExpectedSortOrder[i];
+                if (target is null)
+                {
+                    continue;
+                }
+                for (int j = 0; j < durationsInExpectedSortOrder.Length; j++)
+                {
+                    var expectedResult = Math.Sign(i - j);
+                    var actualResult = target.CompareTo(durationsInExpectedSortOrder[j]);
+                    Assert.AreEqual(expectedResult, actualResult);
+                }
+            }
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/WellKnownTypes/FieldMaskTest.cs

@@ -0,0 +1,245 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2016 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using Google.Protobuf.TestProtos;
+using NUnit.Framework;
+
+namespace Google.Protobuf.WellKnownTypes
+{
+    public class FieldMaskTest
+    {
+        [Test]
+        [TestCase("foo__bar")]
+        [TestCase("foo_3_ar")]
+        [TestCase("fooBar")]
+        public void ToString_Invalid(string input)
+        {
+            var mask = new FieldMask { Paths = { input } };
+            var text = mask.ToString();
+            // More specific test below
+            Assert.That(text, Does.Contain("@warning"));
+            Assert.That(text, Does.Contain(input));
+        }
+
+        [Test]
+        public void ToString_Invalid_Precise()
+        {
+            var mask = new FieldMask { Paths = { "x", "foo__bar", @"x\y" } };
+            Assert.AreEqual(
+                "{ \"@warning\": \"Invalid FieldMask\", \"paths\": [ \"x\", \"foo__bar\", \"x\\\\y\" ] }",
+                mask.ToString());
+        }
+
+        [Test]
+        public void IsValid()
+        {
+            Assert.IsTrue(FieldMask.IsValid<NestedTestAllTypes>("payload"));
+            Assert.IsFalse(FieldMask.IsValid<NestedTestAllTypes>("nonexist"));
+            Assert.IsTrue(FieldMask.IsValid<NestedTestAllTypes>("payload.single_int32"));
+            Assert.IsTrue(FieldMask.IsValid<NestedTestAllTypes>("payload.repeated_int32"));
+            Assert.IsTrue(FieldMask.IsValid<NestedTestAllTypes>("payload.single_nested_message"));
+            Assert.IsTrue(FieldMask.IsValid<NestedTestAllTypes>("payload.repeated_nested_message"));
+            Assert.IsFalse(FieldMask.IsValid<NestedTestAllTypes>("payload.nonexist"));
+
+            Assert.IsTrue(FieldMask.IsValid<NestedTestAllTypes>(FieldMask.FromString("payload")));
+            Assert.IsFalse(FieldMask.IsValid<NestedTestAllTypes>(FieldMask.FromString("nonexist")));
+            Assert.IsFalse(FieldMask.IsValid<NestedTestAllTypes>(FieldMask.FromString("payload,nonexist")));
+
+            Assert.IsTrue(FieldMask.IsValid(NestedTestAllTypes.Descriptor, "payload"));
+            Assert.IsFalse(FieldMask.IsValid(NestedTestAllTypes.Descriptor, "nonexist"));
+
+            Assert.IsTrue(FieldMask.IsValid(NestedTestAllTypes.Descriptor, FieldMask.FromString("payload")));
+            Assert.IsFalse(FieldMask.IsValid(NestedTestAllTypes.Descriptor, FieldMask.FromString("nonexist")));
+
+            Assert.IsTrue(FieldMask.IsValid<NestedTestAllTypes>("payload.single_nested_message.bb"));
+
+            // Repeated fields cannot have sub-paths.
+            Assert.IsFalse(FieldMask.IsValid<NestedTestAllTypes>("payload.repeated_nested_message.bb"));
+
+            // Non-message fields cannot have sub-paths.
+            Assert.IsFalse(FieldMask.IsValid<NestedTestAllTypes>("payload.single_int32.bb"));
+        }
+
+        [Test]
+        [TestCase(new string[] { }, "\"\"")]
+        [TestCase(new string[] { "foo" }, "\"foo\"")]
+        [TestCase(new string[] { "foo", "bar" }, "\"foo,bar\"")]
+        [TestCase(new string[] { "", "foo", "", "bar", "" }, "\",foo,,bar,\"")]
+        public void ToString(string[] input, string expectedOutput)
+        {
+            FieldMask mask = new FieldMask();
+            mask.Paths.AddRange(input);
+            Assert.AreEqual(expectedOutput, mask.ToString());
+        }
+
+        [Test]
+        [TestCase("", new string[] { })]
+        [TestCase("foo", new string[] { "foo" })]
+        [TestCase("foo,bar.baz", new string[] { "foo", "bar.baz" })]
+        [TestCase(",foo,,bar,", new string[] { "foo", "bar" })]
+        public void FromString(string input, string[] expectedOutput)
+        {
+            FieldMask mask = FieldMask.FromString(input);
+            Assert.AreEqual(expectedOutput.Length, mask.Paths.Count);
+            for (int i = 0; i < expectedOutput.Length; i++)
+            {
+                Assert.AreEqual(expectedOutput[i], mask.Paths[i]);
+            }
+        }
+
+        [Test]
+        public void FromString_Validated()
+        {
+            // Check whether the field paths are valid if a class parameter is provided.
+            Assert.DoesNotThrow(() => FieldMask.FromString<NestedTestAllTypes>(",payload"));
+            Assert.Throws<InvalidProtocolBufferException>(() => FieldMask.FromString<NestedTestAllTypes>("payload,nonexist"));
+        }
+
+        [Test]
+        [TestCase(new int[] { }, new string[] { })]
+        [TestCase(new int[] { TestAllTypes.SingleInt32FieldNumber }, new string[] { "single_int32" })]
+        [TestCase(new int[] { TestAllTypes.SingleInt32FieldNumber, TestAllTypes.SingleInt64FieldNumber }, new string[] { "single_int32", "single_int64" })]
+        public void FromFieldNumbers(int[] input, string[] expectedOutput)
+        {
+            FieldMask mask = FieldMask.FromFieldNumbers<TestAllTypes>(input);
+            Assert.AreEqual(expectedOutput.Length, mask.Paths.Count);
+            for (int i = 0; i < expectedOutput.Length; i++)
+            {
+                Assert.AreEqual(expectedOutput[i], mask.Paths[i]);
+            }
+        }
+
+        [Test]
+        public void FromFieldNumbers_Invalid()
+        {
+            Assert.Throws<ArgumentNullException>(() =>
+            {
+                int invalidFieldNumber = 1000;
+                FieldMask.FromFieldNumbers<TestAllTypes>(invalidFieldNumber);
+            });
+        }
+
+        [Test]
+        [TestCase(new string[] { }, "\"\"")]
+        [TestCase(new string[] { "foo" }, "\"foo\"")]
+        [TestCase(new string[] { "foo", "bar" }, "\"foo,bar\"")]
+        [TestCase(new string[] { "", "foo", "", "bar", "" }, "\",foo,bar\"")]
+        public void Normalize(string[] input, string expectedOutput)
+        {
+            FieldMask mask = new FieldMask();
+            mask.Paths.AddRange(input);
+            FieldMask result = mask.Normalize();
+            Assert.AreEqual(expectedOutput, result.ToString());
+        }
+
+        [Test]
+        public void Union()
+        {
+            // Only test a simple case here and expect
+            // {@link FieldMaskTreeTest#AddFieldPath} to cover all scenarios.
+            FieldMask mask1 = FieldMask.FromString("foo,bar.baz,bar.quz");
+            FieldMask mask2 = FieldMask.FromString("foo.bar,bar");
+            FieldMask result = mask1.Union(mask2);
+            Assert.AreEqual(2, result.Paths.Count);
+            Assert.Contains("bar", result.Paths);
+            Assert.Contains("foo", result.Paths);
+            Assert.That(result.Paths, Has.No.Member("bar.baz"));
+            Assert.That(result.Paths, Has.No.Member("bar.quz"));
+            Assert.That(result.Paths, Has.No.Member("foo.bar"));
+        }
+
+        [Test]
+        public void Union_UsingVarArgs()
+        {
+            FieldMask mask1 = FieldMask.FromString("foo");
+            FieldMask mask2 = FieldMask.FromString("foo.bar,bar.quz");
+            FieldMask mask3 = FieldMask.FromString("bar.quz");
+            FieldMask mask4 = FieldMask.FromString("bar");
+            FieldMask result = mask1.Union(mask2, mask3, mask4);
+            Assert.AreEqual(2, result.Paths.Count);
+            Assert.Contains("bar", result.Paths);
+            Assert.Contains("foo", result.Paths);
+            Assert.That(result.Paths, Has.No.Member("foo.bar"));
+            Assert.That(result.Paths, Has.No.Member("bar.quz"));
+        }
+
+        [Test]
+        public void Intersection()
+        {
+            // Only test a simple case here and expect
+            // {@link FieldMaskTreeTest#IntersectFieldPath} to cover all scenarios.
+            FieldMask mask1 = FieldMask.FromString("foo,bar.baz,bar.quz");
+            FieldMask mask2 = FieldMask.FromString("foo.bar,bar");
+            FieldMask result = mask1.Intersection(mask2);
+            Assert.AreEqual(3, result.Paths.Count);
+            Assert.Contains("foo.bar", result.Paths);
+            Assert.Contains("bar.baz", result.Paths);
+            Assert.Contains("bar.quz", result.Paths);
+            Assert.That(result.Paths, Has.No.Member("foo"));
+            Assert.That(result.Paths, Has.No.Member("bar"));
+        }
+
+        [Test]
+        public void Merge()
+        {
+            // Only test a simple case here and expect
+            // {@link FieldMaskTreeTest#Merge} to cover all scenarios.
+            FieldMask fieldMask = FieldMask.FromString("payload");
+            NestedTestAllTypes source = new NestedTestAllTypes
+            {
+                Payload = new TestAllTypes
+                {
+                    SingleInt32 = 1234,
+                    SingleFixed64 = 4321
+                }
+            };
+            NestedTestAllTypes destination = new NestedTestAllTypes();
+            fieldMask.Merge(source, destination);
+            Assert.AreEqual(1234, destination.Payload.SingleInt32);
+            Assert.AreEqual(4321, destination.Payload.SingleFixed64);
+
+            destination = new NestedTestAllTypes
+            {
+                Payload = new TestAllTypes
+                {
+                    SingleInt32 = 4321,
+                    SingleInt64 = 5678
+                }
+            };
+            fieldMask.Merge(source, destination);
+            Assert.AreEqual(1234, destination.Payload.SingleInt32);
+            Assert.AreEqual(5678, destination.Payload.SingleInt64);
+            Assert.AreEqual(4321, destination.Payload.SingleFixed64);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/WellKnownTypes/TimestampTest.cs

@@ -0,0 +1,216 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using NUnit.Framework;
+using System;
+
+namespace Google.Protobuf.WellKnownTypes
+{
+    public class TimestampTest
+    {
+        [Test]
+        public void FromAndToDateTime()
+        {
+            DateTime utcMin = DateTime.SpecifyKind(DateTime.MinValue, DateTimeKind.Utc);
+            DateTime utcMax = DateTime.SpecifyKind(DateTime.MaxValue, DateTimeKind.Utc);
+            AssertRoundtrip(new Timestamp { Seconds = -62135596800 }, utcMin);
+            AssertRoundtrip(new Timestamp { Seconds = 253402300799, Nanos = 999999900 }, utcMax);
+            AssertRoundtrip(new Timestamp(), new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc));
+            AssertRoundtrip(new Timestamp { Nanos = 1000000}, new DateTime(1970, 1, 1, 0, 0, 0, 1, DateTimeKind.Utc));
+            AssertRoundtrip(new Timestamp { Seconds = -1, Nanos = 999000000 }, new DateTime(1969, 12, 31, 23, 59, 59, 999, DateTimeKind.Utc));
+            AssertRoundtrip(new Timestamp { Seconds = 3600 }, new DateTime(1970, 1, 1, 1, 0, 0, DateTimeKind.Utc));
+            AssertRoundtrip(new Timestamp { Seconds = -3600 }, new DateTime(1969, 12, 31, 23, 0, 0, DateTimeKind.Utc));
+        }
+
+        [Test]
+        public void ToDateTimeTruncation()
+        {
+            var t1 = new Timestamp { Seconds = 1, Nanos = 1000000 + Duration.NanosecondsPerTick - 1 };
+            Assert.AreEqual(new DateTime(1970, 1, 1, 0, 0, 1, DateTimeKind.Utc).AddMilliseconds(1), t1.ToDateTime());
+
+            var t2 = new Timestamp { Seconds = -1, Nanos = 1000000 + Duration.NanosecondsPerTick - 1 };
+            Assert.AreEqual(new DateTime(1969, 12, 31, 23, 59, 59).AddMilliseconds(1), t2.ToDateTime());
+        }
+
+        [Test]
+        [TestCase(Timestamp.UnixSecondsAtBclMinValue - 1, Timestamp.MaxNanos)]
+        [TestCase(Timestamp.UnixSecondsAtBclMaxValue + 1, 0)]
+        [TestCase(0, -1)]
+        [TestCase(0, Timestamp.MaxNanos + 1)]
+        public void ToDateTime_OutOfRange(long seconds, int nanoseconds)
+        {
+            var value = new Timestamp { Seconds = seconds, Nanos = nanoseconds };
+            Assert.Throws<InvalidOperationException>(() => value.ToDateTime());
+        }
+
+        // 1ns larger or smaller than the above values
+        [Test]
+        [TestCase(Timestamp.UnixSecondsAtBclMinValue, 0)]
+        [TestCase(Timestamp.UnixSecondsAtBclMaxValue, Timestamp.MaxNanos)]
+        [TestCase(0, 0)]
+        [TestCase(0, Timestamp.MaxNanos)]
+        public void ToDateTime_ValidBoundaries(long seconds, int nanoseconds)
+        {
+            var value = new Timestamp { Seconds = seconds, Nanos = nanoseconds };
+            value.ToDateTime();
+        }
+
+        private static void AssertRoundtrip(Timestamp timestamp, DateTime dateTime)
+        {
+            Assert.AreEqual(timestamp, Timestamp.FromDateTime(dateTime));
+            Assert.AreEqual(dateTime, timestamp.ToDateTime());
+            Assert.AreEqual(DateTimeKind.Utc, timestamp.ToDateTime().Kind);
+        }
+
+        [Test]
+        public void Arithmetic()
+        {
+            Timestamp t1 = new Timestamp { Seconds = 10000, Nanos = 5000 };
+            Timestamp t2 = new Timestamp { Seconds = 8000, Nanos = 10000 };
+            Duration difference = new Duration { Seconds = 1999, Nanos = Duration.NanosecondsPerSecond - 5000 };
+            Assert.AreEqual(difference, t1 - t2);
+            Assert.AreEqual(-difference, t2 - t1);
+
+            Assert.AreEqual(t1, t2 + difference);
+            Assert.AreEqual(t2, t1 - difference);
+        }
+
+        [Test]
+        public void ToString_NonNormalized()
+        {
+            // Just a single example should be sufficient...
+            var duration = new Timestamp { Seconds = 1, Nanos = -1 };
+            Assert.AreEqual("{ \"@warning\": \"Invalid Timestamp\", \"seconds\": \"1\", \"nanos\": -1 }", duration.ToString());
+        }
+
+        [Test]
+        public void Comparability()
+        {
+            Timestamp
+                a = null,
+                b = new Timestamp { Seconds = 1, Nanos = 1 },
+                c = new Timestamp { Seconds = 1, Nanos = 10 },
+                d = new Timestamp { Seconds = 10, Nanos = 1 },
+                e = new Timestamp { Seconds = 10, Nanos = 10 };
+
+            Assert.IsTrue(b.CompareTo(a) > 0); // null is always first (according to default behavior of Array.Sort)
+            Assert.IsTrue(b.CompareTo(b) == 0);
+            Assert.IsTrue(b.CompareTo(b.Clone()) == 0);
+            Assert.IsTrue(b.CompareTo(c) < 0);
+            Assert.IsTrue(b.CompareTo(d) < 0);
+            Assert.IsTrue(b.CompareTo(e) < 0);
+
+            Assert.IsTrue(c.CompareTo(a) > 0);
+            Assert.IsTrue(c.CompareTo(b) > 0);
+            Assert.IsTrue(c.CompareTo(c) == 0);
+            Assert.IsTrue(c.CompareTo(c.Clone()) == 0);
+            Assert.IsTrue(c.CompareTo(d) < 0);
+            Assert.IsTrue(c.CompareTo(e) < 0);
+
+            Assert.IsTrue(d.CompareTo(a) > 0);
+            Assert.IsTrue(d.CompareTo(b) > 0);
+            Assert.IsTrue(d.CompareTo(c) > 0);
+            Assert.IsTrue(d.CompareTo(d) == 0);
+            Assert.IsTrue(d.CompareTo(d.Clone()) == 0);
+            Assert.IsTrue(d.CompareTo(e) < 0);
+
+            Assert.IsTrue(e.CompareTo(a) > 0);
+            Assert.IsTrue(e.CompareTo(b) > 0);
+            Assert.IsTrue(e.CompareTo(c) > 0);
+            Assert.IsTrue(e.CompareTo(d) > 0);
+            Assert.IsTrue(e.CompareTo(e) == 0);
+            Assert.IsTrue(e.CompareTo(e.Clone()) == 0);
+        }
+
+
+        [Test]
+        public void ComparabilityOperators()
+        {
+            Timestamp
+                a = null,
+                b = new Timestamp { Seconds = 1, Nanos = 1 },
+                c = new Timestamp { Seconds = 1, Nanos = 10 },
+                d = new Timestamp { Seconds = 10, Nanos = 1 },
+                e = new Timestamp { Seconds = 10, Nanos = 10 };
+
+#pragma warning disable CS1718 // Comparison made to same variable
+            Assert.IsTrue(b > a);
+            Assert.IsTrue(b == b);
+            Assert.IsTrue(b == b.Clone());
+            Assert.IsTrue(b < c);
+            Assert.IsTrue(b < d);
+            Assert.IsTrue(b < e);
+
+            Assert.IsTrue(c > a);
+            Assert.IsTrue(c > b);
+            Assert.IsTrue(c == c);
+            Assert.IsTrue(c == c.Clone());
+            Assert.IsTrue(c < d);
+            Assert.IsTrue(c < e);
+
+            Assert.IsTrue(d > a);
+            Assert.IsTrue(d > b);
+            Assert.IsTrue(d > c);
+            Assert.IsTrue(d == d);
+            Assert.IsTrue(d == d.Clone());
+            Assert.IsTrue(d < e);
+
+            Assert.IsTrue(e > a);
+            Assert.IsTrue(e > b);
+            Assert.IsTrue(e > c);
+            Assert.IsTrue(e > d);
+            Assert.IsTrue(e == e);
+            Assert.IsTrue(e == e.Clone());
+
+            Assert.IsTrue(b >= a);
+            Assert.IsTrue(b <= c);
+            Assert.IsTrue(b <= d);
+            Assert.IsTrue(b <= e);
+
+            Assert.IsTrue(c >= a);
+            Assert.IsTrue(c >= b);
+            Assert.IsTrue(c <= d);
+            Assert.IsTrue(c <= e);
+
+            Assert.IsTrue(d >= a);
+            Assert.IsTrue(d >= b);
+            Assert.IsTrue(d >= c);
+            Assert.IsTrue(d <= e);
+
+            Assert.IsTrue(e >= a);
+            Assert.IsTrue(e >= b);
+            Assert.IsTrue(e >= c);
+            Assert.IsTrue(e >= d);
+#pragma warning restore CS1718 // Comparison made to same variable
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/WellKnownTypes/WrappersTest.cs

@@ -0,0 +1,546 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using Google.Protobuf.TestProtos;
+using NUnit.Framework;
+using System.Collections;
+using System.IO;
+
+namespace Google.Protobuf.WellKnownTypes
+{
+    public class WrappersTest
+    {
+        [Test]
+        public void NullIsDefault()
+        {
+            var message = new TestWellKnownTypes();
+            Assert.IsNull(message.StringField);
+            Assert.IsNull(message.BytesField);
+            Assert.IsNull(message.BoolField);
+            Assert.IsNull(message.FloatField);
+            Assert.IsNull(message.DoubleField);
+            Assert.IsNull(message.Int32Field);
+            Assert.IsNull(message.Int64Field);
+            Assert.IsNull(message.Uint32Field);
+            Assert.IsNull(message.Uint64Field);
+        }
+
+        [Test]
+        public void NonDefaultSingleValues()
+        {
+            var message = new TestWellKnownTypes
+            {
+                StringField = "x",
+                BytesField = ByteString.CopyFrom(1, 2, 3),
+                BoolField = true,
+                FloatField = 12.5f,
+                DoubleField = 12.25d,
+                Int32Field = 1,
+                Int64Field = 2,
+                Uint32Field = 3,
+                Uint64Field = 4
+            };
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertRoundtrip(TestWellKnownTypes.Parser, message, parsed =>
+            {
+                Assert.AreEqual("x", parsed.StringField);
+                Assert.AreEqual(ByteString.CopyFrom(1, 2, 3), parsed.BytesField);
+                Assert.AreEqual(true, parsed.BoolField);
+                Assert.AreEqual(12.5f, parsed.FloatField);
+                Assert.AreEqual(12.25d, parsed.DoubleField);
+                Assert.AreEqual(1, parsed.Int32Field);
+                Assert.AreEqual(2L, parsed.Int64Field);
+                Assert.AreEqual(3U, parsed.Uint32Field);
+                Assert.AreEqual(4UL, parsed.Uint64Field);
+            });
+        }
+
+        [Test]
+        public void NegativeSingleValues()
+        {
+            var message = new TestWellKnownTypes
+            {
+                FloatField = -12.5f,
+                DoubleField = -12.25d,
+                Int32Field = -1,
+                Int64Field = -2
+            };
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertRoundtrip(TestWellKnownTypes.Parser, message, parsed =>
+            {
+                Assert.AreEqual(-12.5f, parsed.FloatField);
+                Assert.AreEqual(-12.25d, parsed.DoubleField);
+                Assert.AreEqual(-1, parsed.Int32Field);
+                Assert.AreEqual(-2L, parsed.Int64Field);
+            });
+        }
+
+        [Test]
+        public void NonNullDefaultIsPreservedThroughSerialization()
+        {
+            var message = new TestWellKnownTypes
+            {
+                StringField = "",
+                BytesField = ByteString.Empty,
+                BoolField = false,
+                FloatField = 0f,
+                DoubleField = 0d,
+                Int32Field = 0,
+                Int64Field = 0,
+                Uint32Field = 0,
+                Uint64Field = 0
+            };
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertRoundtrip(TestWellKnownTypes.Parser, message, parsed =>
+            {
+                Assert.AreEqual("", parsed.StringField);
+                Assert.AreEqual(ByteString.Empty, parsed.BytesField);
+                Assert.AreEqual(false, parsed.BoolField);
+                Assert.AreEqual(0f, parsed.FloatField);
+                Assert.AreEqual(0d, parsed.DoubleField);
+                Assert.AreEqual(0, parsed.Int32Field);
+                Assert.AreEqual(0L, parsed.Int64Field);
+                Assert.AreEqual(0U, parsed.Uint32Field);
+                Assert.AreEqual(0UL, parsed.Uint64Field);
+            });
+        }
+
+        [Test]
+        public void RepeatedWrappersProhibitNullItems()
+        {
+            var message = new RepeatedWellKnownTypes();
+            Assert.Throws<ArgumentNullException>(() => message.BoolField.Add((bool?) null));
+            Assert.Throws<ArgumentNullException>(() => message.Int32Field.Add((int?) null));
+            Assert.Throws<ArgumentNullException>(() => message.StringField.Add((string) null));
+            Assert.Throws<ArgumentNullException>(() => message.BytesField.Add((ByteString) null));
+        }
+
+        [Test]
+        public void RepeatedWrappersSerializeDeserialize()
+        {
+            var message = new RepeatedWellKnownTypes
+            {
+                BoolField = { true, false },
+                BytesField = { ByteString.CopyFrom(1, 2, 3), ByteString.CopyFrom(4, 5, 6), ByteString.Empty },
+                DoubleField = { 12.5, -1.5, 0d },
+                FloatField = { 123.25f, -20f, 0f },
+                Int32Field = { int.MaxValue, int.MinValue, 0 },
+                Int64Field = { long.MaxValue, long.MinValue, 0L },
+                StringField = { "First", "Second", "" },
+                Uint32Field = { uint.MaxValue, uint.MinValue, 0U },
+                Uint64Field = { ulong.MaxValue, ulong.MinValue, 0UL },
+            };
+
+            // Just to test a single value for sanity...
+            Assert.AreEqual("Second", message.StringField[1]);
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertRoundtrip(RepeatedWellKnownTypes.Parser, message);
+        }
+
+        [Test]
+        public void RepeatedWrappersBinaryFormat()
+        {
+            // At one point we accidentally used a packed format for repeated wrappers, which is wrong (and weird).
+            // This test is just to prove that we use the right format.
+
+            var rawOutput = new MemoryStream();
+            var output = new CodedOutputStream(rawOutput);
+            // Write a value of 5
+            output.WriteTag(RepeatedWellKnownTypes.Int32FieldFieldNumber, WireFormat.WireType.LengthDelimited);
+            output.WriteLength(2);
+            output.WriteTag(WrappersReflection.WrapperValueFieldNumber, WireFormat.WireType.Varint);
+            output.WriteInt32(5);
+            // Write a value of 0 (empty message)
+            output.WriteTag(RepeatedWellKnownTypes.Int32FieldFieldNumber, WireFormat.WireType.LengthDelimited);
+            output.WriteLength(0);
+            output.Flush();
+            var expectedBytes = rawOutput.ToArray();
+
+            var message = new RepeatedWellKnownTypes { Int32Field = { 5, 0 } };
+            var actualBytes = message.ToByteArray();
+            Assert.AreEqual(expectedBytes, actualBytes);
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+        }
+
+        [Test]
+        public void MapWrappersSerializeDeserialize()
+        {
+            // Note: no null values here, as they are prohibited in map fields
+            // (despite being representable).
+            var message = new MapWellKnownTypes
+            {
+                BoolField = { { 10, false }, { 20, true } },
+                BytesField = {
+                    { -1, ByteString.CopyFrom(1, 2, 3) },
+                    { 10, ByteString.CopyFrom(4, 5, 6) },
+                    { 1000, ByteString.Empty },
+                },
+                DoubleField = { { 1, 12.5 }, { 10, -1.5 }, { 20, 0d } },
+                FloatField = { { 2, 123.25f }, { 3, -20f }, { 4, 0f } },
+                Int32Field = { { 5, int.MaxValue }, { 6, int.MinValue }, { 7, 0 } },
+                Int64Field = { { 8, long.MaxValue }, { 9, long.MinValue }, { 10, 0L } },
+                StringField = { { 11, "First" }, { 12, "Second" }, { 13, "" } },
+                Uint32Field = { { 15, uint.MaxValue }, { 16, uint.MinValue }, { 17, 0U } },
+                Uint64Field = { { 18, ulong.MaxValue }, { 19, ulong.MinValue }, { 20, 0UL } },
+            };
+
+            // Just to test a single value for sanity...
+            Assert.AreEqual("Second", message.StringField[12]);
+
+            MessageParsingHelpers.AssertWritingMessage(message);
+
+            MessageParsingHelpers.AssertRoundtrip(MapWellKnownTypes.Parser, message);
+        }
+
+        [Test]
+        public void Reflection_SingleValues()
+        {
+            var message = new TestWellKnownTypes
+            {
+                StringField = "x",
+                BytesField = ByteString.CopyFrom(1, 2, 3),
+                BoolField = true,
+                FloatField = 12.5f,
+                DoubleField = 12.25d,
+                Int32Field = 1,
+                Int64Field = 2,
+                Uint32Field = 3,
+                Uint64Field = 4
+            };
+            var fields = TestWellKnownTypes.Descriptor.Fields;
+
+            Assert.AreEqual("x", fields[TestWellKnownTypes.StringFieldFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(ByteString.CopyFrom(1, 2, 3), fields[TestWellKnownTypes.BytesFieldFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(true, fields[TestWellKnownTypes.BoolFieldFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(12.5f, fields[TestWellKnownTypes.FloatFieldFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(12.25d, fields[TestWellKnownTypes.DoubleFieldFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(1, fields[TestWellKnownTypes.Int32FieldFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(2L, fields[TestWellKnownTypes.Int64FieldFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(3U, fields[TestWellKnownTypes.Uint32FieldFieldNumber].Accessor.GetValue(message));
+            Assert.AreEqual(4UL, fields[TestWellKnownTypes.Uint64FieldFieldNumber].Accessor.GetValue(message));
+
+            // And a couple of null fields...
+            message.StringField = null;
+            message.FloatField = null;
+            Assert.IsNull(fields[TestWellKnownTypes.StringFieldFieldNumber].Accessor.GetValue(message));
+            Assert.IsNull(fields[TestWellKnownTypes.FloatFieldFieldNumber].Accessor.GetValue(message));
+        }
+
+        [Test]
+        public void Reflection_RepeatedFields()
+        {
+            // Just a single example... note that we can't have a null value here
+            var message = new RepeatedWellKnownTypes { Int32Field = { 1, 2 } };
+            var fields = RepeatedWellKnownTypes.Descriptor.Fields;
+            var list = (IList) fields[RepeatedWellKnownTypes.Int32FieldFieldNumber].Accessor.GetValue(message);
+            CollectionAssert.AreEqual(new[] { 1, 2 }, list);
+        }
+
+        [Test]
+        public void Reflection_MapFields()
+        {
+            // Just a single example... note that we can't have a null value here despite the value type being int?
+            var message = new MapWellKnownTypes { Int32Field = { { 1, 2 } } };
+            var fields = MapWellKnownTypes.Descriptor.Fields;
+            var dictionary = (IDictionary) fields[MapWellKnownTypes.Int32FieldFieldNumber].Accessor.GetValue(message);
+            Assert.AreEqual(2, dictionary[1]);
+        }
+
+        [Test]
+        public void Oneof()
+        {
+            var message = new OneofWellKnownTypes { EmptyField = new Empty() };
+            // Start off with a non-wrapper
+            Assert.AreEqual(OneofWellKnownTypes.OneofFieldOneofCase.EmptyField, message.OneofFieldCase);
+            AssertOneofRoundTrip(message);
+
+            message.StringField = "foo";
+            Assert.AreEqual(OneofWellKnownTypes.OneofFieldOneofCase.StringField, message.OneofFieldCase);
+            AssertOneofRoundTrip(message);
+
+            message.StringField = "foo";
+            Assert.AreEqual(OneofWellKnownTypes.OneofFieldOneofCase.StringField, message.OneofFieldCase);
+            AssertOneofRoundTrip(message);
+
+            message.DoubleField = 0.0f;
+            Assert.AreEqual(OneofWellKnownTypes.OneofFieldOneofCase.DoubleField, message.OneofFieldCase);
+            AssertOneofRoundTrip(message);
+
+            message.DoubleField = 1.0f;
+            Assert.AreEqual(OneofWellKnownTypes.OneofFieldOneofCase.DoubleField, message.OneofFieldCase);
+            AssertOneofRoundTrip(message);
+
+            message.ClearOneofField();
+            Assert.AreEqual(OneofWellKnownTypes.OneofFieldOneofCase.None, message.OneofFieldCase);
+            AssertOneofRoundTrip(message);
+        }
+
+        private void AssertOneofRoundTrip(OneofWellKnownTypes message)
+        {
+            // Normal roundtrip, but explicitly checking the case...
+            MessageParsingHelpers.AssertRoundtrip(OneofWellKnownTypes.Parser, message, parsed =>
+            {
+                Assert.AreEqual(message.OneofFieldCase, parsed.OneofFieldCase);
+            });
+        }
+
+        [Test]
+        [TestCase("x", "y", "y")]
+        [TestCase("x", "", "x")]
+        [TestCase("x", null, "x")]
+        [TestCase("", "y", "y")]
+        [TestCase("", "", "")]
+        [TestCase("", null, "")]
+        [TestCase(null, "y", "y")]
+        [TestCase(null, "", "")]
+        [TestCase(null, null, null)]
+        public void Merging(string original, string merged, string expected)
+        {
+            var originalMessage = new TestWellKnownTypes { StringField = original };
+            var mergingMessage = new TestWellKnownTypes { StringField = merged };
+            originalMessage.MergeFrom(mergingMessage);
+            Assert.AreEqual(expected, originalMessage.StringField);
+
+            // Try it using MergeFrom(CodedInputStream) too...
+            originalMessage = new TestWellKnownTypes { StringField = original };
+            originalMessage.MergeFrom(mergingMessage.ToByteArray());
+            Assert.AreEqual(expected, originalMessage.StringField);
+        }
+
+        // Merging is odd with wrapper types, due to the way that default values aren't emitted in
+        // the binary stream. In fact we cheat a little bit - a message with an explicitly present default
+        // value will have that default value ignored. See issue 615. Fixing this would require significant upheaval to
+        // the FieldCodec side of things.
+        [Test]
+        public void MergingStreamExplicitValue()
+        {
+            var message = new TestWellKnownTypes { Int32Field = 5 };
+
+            // Create a byte array which has the data of an Int32Value explicitly containing a value of 0.
+            // This wouldn't normally happen.
+            byte[] bytes;
+            var wrapperTag = WireFormat.MakeTag(TestWellKnownTypes.Int32FieldFieldNumber, WireFormat.WireType.LengthDelimited);
+            var valueTag = WireFormat.MakeTag(Int32Value.ValueFieldNumber, WireFormat.WireType.Varint);
+            using (var stream = new MemoryStream())
+            {
+                var coded = new CodedOutputStream(stream);
+                coded.WriteTag(wrapperTag);
+                coded.WriteLength(2); // valueTag + a value 0, each one byte
+                coded.WriteTag(valueTag);
+                coded.WriteInt32(0);
+                coded.Flush();
+                bytes = stream.ToArray();
+            }
+
+            message.MergeFrom(bytes);
+            // A normal implementation would have 0 now, as the explicit default would have been overwritten the 5.
+            // With the FieldCodec for Nullable<int>, we can't tell the difference between an implicit 0 and an explicit 0.
+            Assert.AreEqual(5, message.Int32Field);
+        }
+
+        [Test]
+        public void MergingStreamNoValue()
+        {
+            var message = new TestWellKnownTypes { Int32Field = 5 };
+
+            // Create a byte array which an Int32 field, but with no value.
+            var bytes = new TestWellKnownTypes { Int32Field = 0 }.ToByteArray();
+            Assert.AreEqual(2, bytes.Length); // The tag for Int32Field is a single byte, then a byte indicating a 0-length message.
+            message.MergeFrom(bytes);
+
+            // The "implicit" 0 did *not* overwrite the value.
+            // (This is the correct behaviour.)
+            Assert.AreEqual(5, message.Int32Field);
+        }
+
+        // All permutations of origin/merging value being null, zero (default) or non-default.
+        // As this is the in-memory version, we don't need to worry about the difference between implicit and explicit 0.
+        [Test]
+        [TestCase(null, null, null)]
+        [TestCase(null, 0, 0)]
+        [TestCase(null, 5, 5)]
+        [TestCase(0, null, 0)]
+        [TestCase(0, 0, 0)]
+        [TestCase(0, 5, 5)]
+        [TestCase(5, null, 5)]
+        [TestCase(5, 0, 5)]
+        [TestCase(5, 10, 10)]
+        public void MergingMessageWithZero(int? originValue, int? mergingValue, int? expectedResult)
+        {
+            // This differs from the MergingStreamCornerCase because when we merge message *objects*,
+            // we ignore default values from the "source".
+            var message1 = new TestWellKnownTypes { Int32Field = originValue };
+            var message2 = new TestWellKnownTypes { Int32Field = mergingValue };
+            message1.MergeFrom(message2);
+            Assert.AreEqual(expectedResult, message1.Int32Field);
+        }
+
+        [Test]
+        public void UnknownFieldInWrapperInt32FastPath()
+        {
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            var wrapperTag = WireFormat.MakeTag(TestWellKnownTypes.Int32FieldFieldNumber, WireFormat.WireType.LengthDelimited);
+            var unknownTag = WireFormat.MakeTag(15, WireFormat.WireType.Varint);
+            var valueTag = WireFormat.MakeTag(Int32Value.ValueFieldNumber, WireFormat.WireType.Varint);
+
+            output.WriteTag(wrapperTag);
+            // Wrapper message is just long enough - 6 bytes - to use the wrapper fast-path.
+            output.WriteLength(6); // unknownTag + value 5 + valueType, each 1 byte, + value 65536, 3 bytes
+            output.WriteTag(unknownTag);
+            output.WriteInt32((int) valueTag); // Sneakily "pretend" it's a tag when it's really a value
+            output.WriteTag(valueTag);
+            output.WriteInt32(65536);
+            
+            output.Flush();
+            Assert.AreEqual(8, stream.Length); // tag (1 byte) + length (1 byte) + message (6 bytes)
+            stream.Position = 0;
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestWellKnownTypes.Parser,
+                stream.ToArray(),
+                message => Assert.AreEqual(65536, message.Int32Field));
+        }
+
+        [Test]
+        public void UnknownFieldInWrapperInt32SlowPath()
+        {
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            var wrapperTag = WireFormat.MakeTag(TestWellKnownTypes.Int32FieldFieldNumber, WireFormat.WireType.LengthDelimited);
+            var unknownTag = WireFormat.MakeTag(15, WireFormat.WireType.Varint);
+            var valueTag = WireFormat.MakeTag(Int32Value.ValueFieldNumber, WireFormat.WireType.Varint);
+
+            output.WriteTag(wrapperTag);
+            // Wrapper message is too short to be used on the wrapper fast-path.
+            output.WriteLength(4); // unknownTag + value 5 + valueType + value 6, each 1 byte
+            output.WriteTag(unknownTag);
+            output.WriteInt32((int)valueTag); // Sneakily "pretend" it's a tag when it's really a value
+            output.WriteTag(valueTag);
+            output.WriteInt32(6);
+
+            output.Flush();
+            Assert.Less(stream.Length, 8); // tag (1 byte) + length (1 byte) + message
+            stream.Position = 0;
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestWellKnownTypes.Parser,
+                stream.ToArray(),
+                message => Assert.AreEqual(6, message.Int32Field));
+        }
+
+        [Test]
+        public void UnknownFieldInWrapperInt64FastPath()
+        {
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            var wrapperTag = WireFormat.MakeTag(TestWellKnownTypes.Int64FieldFieldNumber, WireFormat.WireType.LengthDelimited);
+            var unknownTag = WireFormat.MakeTag(15, WireFormat.WireType.Varint);
+            var valueTag = WireFormat.MakeTag(Int64Value.ValueFieldNumber, WireFormat.WireType.Varint);
+
+            output.WriteTag(wrapperTag);
+            // Wrapper message is just long enough - 10 bytes - to use the wrapper fast-path.
+            output.WriteLength(11); // unknownTag + value 5 + valueType, each 1 byte, + value 0xfffffffffffff, 8 bytes
+            output.WriteTag(unknownTag);
+            output.WriteInt64((int)valueTag); // Sneakily "pretend" it's a tag when it's really a value
+            output.WriteTag(valueTag);
+            output.WriteInt64(0xfffffffffffffL);
+
+            output.Flush();
+            Assert.AreEqual(13, stream.Length); // tag (1 byte) + length (1 byte) + message (11 bytes)
+            stream.Position = 0;
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestWellKnownTypes.Parser,
+                stream.ToArray(),
+                message => Assert.AreEqual(0xfffffffffffffL, message.Int64Field));
+        }
+
+        [Test]
+        public void UnknownFieldInWrapperInt64SlowPath()
+        {
+            var stream = new MemoryStream();
+            var output = new CodedOutputStream(stream);
+            var wrapperTag = WireFormat.MakeTag(TestWellKnownTypes.Int64FieldFieldNumber, WireFormat.WireType.LengthDelimited);
+            var unknownTag = WireFormat.MakeTag(15, WireFormat.WireType.Varint);
+            var valueTag = WireFormat.MakeTag(Int64Value.ValueFieldNumber, WireFormat.WireType.Varint);
+
+            output.WriteTag(wrapperTag);
+            // Wrapper message is too short to be used on the wrapper fast-path.
+            output.WriteLength(4); // unknownTag + value 5 + valueType + value 6, each 1 byte
+            output.WriteTag(unknownTag);
+            output.WriteInt64((int)valueTag); // Sneakily "pretend" it's a tag when it's really a value
+            output.WriteTag(valueTag);
+            output.WriteInt64(6);
+
+            output.Flush();
+            Assert.Less(stream.Length, 12); // tag (1 byte) + length (1 byte) + message
+            stream.Position = 0;
+
+            MessageParsingHelpers.AssertReadingMessage(
+                TestWellKnownTypes.Parser,
+                stream.ToArray(),
+                message => Assert.AreEqual(6L, message.Int64Field));
+        }
+
+        [Test]
+        public void ClearWithReflection()
+        {
+            // String and Bytes are the tricky ones here, as the CLR type of the property
+            // is the same between the wrapper and non-wrapper types.
+            var message = new TestWellKnownTypes { StringField = "foo" };
+            TestWellKnownTypes.Descriptor.Fields[TestWellKnownTypes.StringFieldFieldNumber].Accessor.Clear(message);
+            Assert.IsNull(message.StringField);
+        }
+
+        [Test]
+        public void NaNComparisons()
+        {
+            var message1 = new TestWellKnownTypes { DoubleField = SampleNaNs.Regular };
+            var message2 = new TestWellKnownTypes { DoubleField = SampleNaNs.PayloadFlipped };
+            var message3 = new TestWellKnownTypes { DoubleField = SampleNaNs.Regular };
+
+            EqualityTester.AssertInequality(message1, message2);
+            EqualityTester.AssertEquality(message1, message3);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.Test/WritingPrimitivesTest.cs

@@ -0,0 +1,61 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2022 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Google.Protobuf.Test;
+
+internal class WritingPrimitivesTest
+{
+    [Test]
+    public void WriteRawString_IllFormedUnicodeString()
+    {
+        // See https://codeblog.jonskeet.uk/2014/11/07/when-is-a-string-not-a-string/
+        char c1 = '\u0058';
+        char c2 = '\ud800';
+        char c3 = '\u0059';
+        string text = new string(new[] { c1, c2, c3 });
+        Span<byte> buffer = new byte[10];
+        WriteContext.Initialize(ref buffer, out var context);
+        WritingPrimitives.WriteString(ref context.buffer, ref context.state, text);
+
+        // The high surrogate is written out in a "raw" form, surrounded by the ASCII
+        // characters.
+        byte[] expectedBytes = { 0x5, 0x58, 0xef, 0xbf, 0xbd, 0x59 };
+        Assert.AreEqual(expectedBytes, buffer.Slice(0, context.state.position).ToArray());
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf.sln

@@ -0,0 +1,54 @@
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 15
+VisualStudioVersion = 15.0.26114.2
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "AddressBook", "AddressBook\AddressBook.csproj", "{AFB63919-1E05-43B4-802A-8FB8C9B2F463}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Google.Protobuf", "Google.Protobuf\Google.Protobuf.csproj", "{9B576380-726D-4142-8238-60A43AB0E35A}"
+EndProject
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+EndProject
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+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Google.Protobuf.JsonDump", "Google.Protobuf.JsonDump\Google.Protobuf.JsonDump.csproj", "{9695E08F-9829-497D-B95C-B38F28D48690}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Google.Protobuf.Test.TestProtos", "Google.Protobuf.Test.TestProtos\Google.Protobuf.Test.TestProtos.csproj", "{ADF24BEB-A318-4530-8448-356B72B820EA}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{AFB63919-1E05-43B4-802A-8FB8C9B2F463}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
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+		{9B576380-726D-4142-8238-60A43AB0E35A}.Debug|Any CPU.Build.0 = Debug|Any CPU
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+		{9B576380-726D-4142-8238-60A43AB0E35A}.Release|Any CPU.Build.0 = Release|Any CPU
+		{580EB013-D3C7-4578-B845-015F4A3B0591}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
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+		{580EB013-D3C7-4578-B845-015F4A3B0591}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{580EB013-D3C7-4578-B845-015F4A3B0591}.Release|Any CPU.Build.0 = Release|Any CPU
+		{DDDC055B-E185-4181-BAB0-072F0F984569}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{DDDC055B-E185-4181-BAB0-072F0F984569}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{DDDC055B-E185-4181-BAB0-072F0F984569}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{DDDC055B-E185-4181-BAB0-072F0F984569}.Release|Any CPU.Build.0 = Release|Any CPU
+		{9695E08F-9829-497D-B95C-B38F28D48690}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{9695E08F-9829-497D-B95C-B38F28D48690}.Debug|Any CPU.Build.0 = Debug|Any CPU
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+		{ADF24BEB-A318-4530-8448-356B72B820EA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{ADF24BEB-A318-4530-8448-356B72B820EA}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{ADF24BEB-A318-4530-8448-356B72B820EA}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{ADF24BEB-A318-4530-8448-356B72B820EA}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {7B06C87B-83E1-4F5F-A0DD-6E9AFAC03DAC}
+	EndGlobalSection
+EndGlobal

libs/protobuf/csharp/src/Google.Protobuf/ByteArray.cs

@@ -0,0 +1,79 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Provides a utility routine to copy small arrays much more quickly than Buffer.BlockCopy
+    /// </summary>
+    internal static class ByteArray
+    {
+        /// <summary>
+        /// The threshold above which you should use Buffer.BlockCopy rather than ByteArray.Copy
+        /// </summary>
+        private const int CopyThreshold = 12;
+
+        /// <summary>
+        /// Determines which copy routine to use based on the number of bytes to be copied.
+        /// </summary>
+        internal static void Copy(byte[] src, int srcOffset, byte[] dst, int dstOffset, int count)
+        {
+            if (count > CopyThreshold)
+            {
+                Buffer.BlockCopy(src, srcOffset, dst, dstOffset, count);
+            }
+            else
+            {
+                int stop = srcOffset + count;
+                for (int i = srcOffset; i < stop; i++)
+                {
+                    dst[dstOffset++] = src[i];
+                }
+            }
+        }
+
+        /// <summary>
+        /// Reverses the order of bytes in the array
+        /// </summary>
+        internal static void Reverse(byte[] bytes)
+        {
+            for (int first = 0, last = bytes.Length - 1; first < last; first++, last--)
+            {
+                byte temp = bytes[first];
+                bytes[first] = bytes[last];
+                bytes[last] = temp;
+            }
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf/ByteString.cs

@@ -0,0 +1,427 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.IO;
+using System.Runtime.InteropServices;
+using System.Security;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Immutable array of bytes.
+    /// </summary>
+    [SecuritySafeCritical]
+    public sealed class ByteString : IEnumerable<byte>, IEquatable<ByteString>
+    {
+        private static readonly ByteString empty = new ByteString(new byte[0]);
+
+        private readonly ReadOnlyMemory<byte> bytes;
+
+        /// <summary>
+        /// Internal use only. Ensure that the provided memory is not mutated and belongs to this instance.
+        /// </summary>
+        internal static ByteString AttachBytes(ReadOnlyMemory<byte> bytes)
+        {
+            return new ByteString(bytes);
+        }
+
+        /// <summary>
+        /// Internal use only. Ensure that the provided memory is not mutated and belongs to this instance.
+        /// This method encapsulates converting array to memory. Reduces need for SecuritySafeCritical
+        /// in .NET Framework.
+        /// </summary>
+        internal static ByteString AttachBytes(byte[] bytes)
+        {
+            return AttachBytes(bytes.AsMemory());
+        }
+
+        /// <summary>
+        /// Constructs a new ByteString from the given memory. The memory is
+        /// *not* copied, and must not be modified after this constructor is called.
+        /// </summary>
+        private ByteString(ReadOnlyMemory<byte> bytes)
+        {
+            this.bytes = bytes;
+        }
+
+        /// <summary>
+        /// Returns an empty ByteString.
+        /// </summary>
+        public static ByteString Empty
+        {
+            get { return empty; }
+        }
+
+        /// <summary>
+        /// Returns the length of this ByteString in bytes.
+        /// </summary>
+        public int Length
+        {
+            get { return bytes.Length; }
+        }
+
+        /// <summary>
+        /// Returns <c>true</c> if this byte string is empty, <c>false</c> otherwise.
+        /// </summary>
+        public bool IsEmpty
+        {
+            get { return Length == 0; }
+        }
+
+        /// <summary>
+        /// Provides read-only access to the data of this <see cref="ByteString"/>.
+        /// No data is copied so this is the most efficient way of accessing.
+        /// </summary>
+        public ReadOnlySpan<byte> Span
+        {
+            get { return bytes.Span; }
+        }
+
+        /// <summary>
+        /// Provides read-only access to the data of this <see cref="ByteString"/>.
+        /// No data is copied so this is the most efficient way of accessing.
+        /// </summary>
+        public ReadOnlyMemory<byte> Memory
+        {
+            get { return bytes; }
+        }
+
+        /// <summary>
+        /// Converts this <see cref="ByteString"/> into a byte array.
+        /// </summary>
+        /// <remarks>The data is copied - changes to the returned array will not be reflected in this <c>ByteString</c>.</remarks>
+        /// <returns>A byte array with the same data as this <c>ByteString</c>.</returns>
+        public byte[] ToByteArray()
+        {
+            return bytes.ToArray();
+        }
+
+        /// <summary>
+        /// Converts this <see cref="ByteString"/> into a standard base64 representation.
+        /// </summary>
+        /// <returns>A base64 representation of this <c>ByteString</c>.</returns>
+        public string ToBase64()
+        {
+            if (MemoryMarshal.TryGetArray(bytes, out ArraySegment<byte> segment))
+            {
+                // Fast path. ByteString was created with an array, so pass the underlying array.
+                return Convert.ToBase64String(segment.Array, segment.Offset, segment.Count);
+            }
+            else
+            {
+                // Slow path. BytesString is not an array. Convert memory and pass result to ToBase64String.
+                return Convert.ToBase64String(bytes.ToArray());
+            }
+        }
+
+        /// <summary>
+        /// Constructs a <see cref="ByteString" /> from the Base64 Encoded String.
+        /// </summary>
+        public static ByteString FromBase64(string bytes)
+        {
+            // By handling the empty string explicitly, we not only optimize but we fix a
+            // problem on CF 2.0. See issue 61 for details.
+            return bytes == "" ? Empty : new ByteString(Convert.FromBase64String(bytes));
+        }
+
+        /// <summary>
+        /// Constructs a <see cref="ByteString"/> from data in the given stream, synchronously.
+        /// </summary>
+        /// <remarks>If successful, <paramref name="stream"/> will be read completely, from the position
+        /// at the start of the call.</remarks>
+        /// <param name="stream">The stream to copy into a ByteString.</param>
+        /// <returns>A ByteString with content read from the given stream.</returns>
+        public static ByteString FromStream(Stream stream)
+        {
+            ProtoPreconditions.CheckNotNull(stream, nameof(stream));
+            int capacity = stream.CanSeek ? checked((int) (stream.Length - stream.Position)) : 0;
+            var memoryStream = new MemoryStream(capacity);
+            stream.CopyTo(memoryStream);
+#if NETSTANDARD1_1 || NETSTANDARD2_0
+            byte[] bytes = memoryStream.ToArray();
+#else
+            // Avoid an extra copy if we can.
+            byte[] bytes = memoryStream.Length == memoryStream.Capacity ? memoryStream.GetBuffer() : memoryStream.ToArray();
+#endif
+            return AttachBytes(bytes);
+        }
+
+        /// <summary>
+        /// Constructs a <see cref="ByteString"/> from data in the given stream, asynchronously.
+        /// </summary>
+        /// <remarks>If successful, <paramref name="stream"/> will be read completely, from the position
+        /// at the start of the call.</remarks>
+        /// <param name="stream">The stream to copy into a ByteString.</param>
+        /// <param name="cancellationToken">The cancellation token to use when reading from the stream, if any.</param>
+        /// <returns>A ByteString with content read from the given stream.</returns>
+        public static Task<ByteString> FromStreamAsync(Stream stream, CancellationToken cancellationToken = default)
+        {
+            ProtoPreconditions.CheckNotNull(stream, nameof(stream));
+            return ByteStringAsync.FromStreamAsyncCore(stream, cancellationToken);
+        }
+
+        /// <summary>
+        /// Constructs a <see cref="ByteString" /> from the given array. The contents
+        /// are copied, so further modifications to the array will not
+        /// be reflected in the returned ByteString.
+        /// This method can also be invoked in <c>ByteString.CopyFrom(0xaa, 0xbb, ...)</c> form
+        /// which is primarily useful for testing.
+        /// </summary>
+        public static ByteString CopyFrom(params byte[] bytes)
+        {
+            return new ByteString((byte[]) bytes.Clone());
+        }
+
+        /// <summary>
+        /// Constructs a <see cref="ByteString" /> from a portion of a byte array.
+        /// </summary>
+        public static ByteString CopyFrom(byte[] bytes, int offset, int count)
+        {
+            byte[] portion = new byte[count];
+            ByteArray.Copy(bytes, offset, portion, 0, count);
+            return new ByteString(portion);
+        }
+
+        /// <summary>
+        /// Constructs a <see cref="ByteString" /> from a read only span. The contents
+        /// are copied, so further modifications to the span will not
+        /// be reflected in the returned <see cref="ByteString" />.
+        /// </summary>
+        public static ByteString CopyFrom(ReadOnlySpan<byte> bytes)
+        {
+            return new ByteString(bytes.ToArray());
+        }
+
+        /// <summary>
+        /// Creates a new <see cref="ByteString" /> by encoding the specified text with
+        /// the given encoding.
+        /// </summary>
+        public static ByteString CopyFrom(string text, Encoding encoding)
+        {
+            return new ByteString(encoding.GetBytes(text));
+        }
+
+        /// <summary>
+        /// Creates a new <see cref="ByteString" /> by encoding the specified text in UTF-8.
+        /// </summary>
+        public static ByteString CopyFromUtf8(string text)
+        {
+            return CopyFrom(text, Encoding.UTF8);
+        }
+
+        /// <summary>
+        /// Returns the byte at the given index.
+        /// </summary>
+        public byte this[int index]
+        {
+            get { return bytes.Span[index]; }
+        }
+
+        /// <summary>
+        /// Converts this <see cref="ByteString"/> into a string by applying the given encoding.
+        /// </summary>
+        /// <remarks>
+        /// This method should only be used to convert binary data which was the result of encoding
+        /// text with the given encoding.
+        /// </remarks>
+        /// <param name="encoding">The encoding to use to decode the binary data into text.</param>
+        /// <returns>The result of decoding the binary data with the given decoding.</returns>
+        public string ToString(Encoding encoding)
+        {
+            if (MemoryMarshal.TryGetArray(bytes, out ArraySegment<byte> segment))
+            {
+                // Fast path. ByteString was created with an array.
+                return encoding.GetString(segment.Array, segment.Offset, segment.Count);
+            }
+            else
+            {
+                // Slow path. BytesString is not an array. Convert memory and pass result to GetString.
+                // TODO: Consider using GetString overload that takes a pointer.
+                byte[] array = bytes.ToArray();
+                return encoding.GetString(array, 0, array.Length);
+            }
+        }
+
+        /// <summary>
+        /// Converts this <see cref="ByteString"/> into a string by applying the UTF-8 encoding.
+        /// </summary>
+        /// <remarks>
+        /// This method should only be used to convert binary data which was the result of encoding
+        /// text with UTF-8.
+        /// </remarks>
+        /// <returns>The result of decoding the binary data with the given decoding.</returns>
+        public string ToStringUtf8()
+        {
+            return ToString(Encoding.UTF8);
+        }
+
+        /// <summary>
+        /// Returns an iterator over the bytes in this <see cref="ByteString"/>.
+        /// </summary>
+        /// <returns>An iterator over the bytes in this object.</returns>
+        [SecuritySafeCritical]
+        public IEnumerator<byte> GetEnumerator()
+        {
+            return MemoryMarshal.ToEnumerable(bytes).GetEnumerator();
+        }
+
+        /// <summary>
+        /// Returns an iterator over the bytes in this <see cref="ByteString"/>.
+        /// </summary>
+        /// <returns>An iterator over the bytes in this object.</returns>
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
+
+        /// <summary>
+        /// Creates a CodedInputStream from this ByteString's data.
+        /// </summary>
+        public CodedInputStream CreateCodedInput()
+        {
+            // We trust CodedInputStream not to reveal the provided byte array or modify it
+            if (MemoryMarshal.TryGetArray(bytes, out ArraySegment<byte> segment) && segment.Count == bytes.Length)
+            {
+                // Fast path. ByteString was created with a complete array.
+                return new CodedInputStream(segment.Array, segment.Offset, segment.Count);
+            }
+            else
+            {
+                // Slow path. BytesString is not an array, or is a slice of an array.
+                // Convert memory and pass result to WriteRawBytes.
+                return new CodedInputStream(bytes.ToArray());
+            }
+        }
+
+        /// <summary>
+        /// Compares two byte strings for equality.
+        /// </summary>
+        /// <param name="lhs">The first byte string to compare.</param>
+        /// <param name="rhs">The second byte string to compare.</param>
+        /// <returns><c>true</c> if the byte strings are equal; false otherwise.</returns>
+        public static bool operator ==(ByteString lhs, ByteString rhs)
+        {
+            if (ReferenceEquals(lhs, rhs))
+            {
+                return true;
+            }
+            if (lhs is null || rhs is null)
+            {
+                return false;
+            }
+
+            return lhs.bytes.Span.SequenceEqual(rhs.bytes.Span);
+        }
+
+        /// <summary>
+        /// Compares two byte strings for inequality.
+        /// </summary>
+        /// <param name="lhs">The first byte string to compare.</param>
+        /// <param name="rhs">The second byte string to compare.</param>
+        /// <returns><c>false</c> if the byte strings are equal; true otherwise.</returns>
+        public static bool operator !=(ByteString lhs, ByteString rhs)
+        {
+            return !(lhs == rhs);
+        }
+
+        /// <summary>
+        /// Compares this byte string with another object.
+        /// </summary>
+        /// <param name="obj">The object to compare this with.</param>
+        /// <returns><c>true</c> if <paramref name="obj"/> refers to an equal <see cref="ByteString"/>; <c>false</c> otherwise.</returns>
+        [SecuritySafeCritical]
+        public override bool Equals(object obj)
+        {
+            return this == (obj as ByteString);
+        }
+
+        /// <summary>
+        /// Returns a hash code for this object. Two equal byte strings
+        /// will return the same hash code.
+        /// </summary>
+        /// <returns>A hash code for this object.</returns>
+        [SecuritySafeCritical]
+        public override int GetHashCode()
+        {
+            ReadOnlySpan<byte> b = bytes.Span;
+
+            int ret = 23;
+            for (int i = 0; i < b.Length; i++)
+            {
+                ret = (ret * 31) + b[i];
+            }
+            return ret;
+        }
+
+        /// <summary>
+        /// Compares this byte string with another.
+        /// </summary>
+        /// <param name="other">The <see cref="ByteString"/> to compare this with.</param>
+        /// <returns><c>true</c> if <paramref name="other"/> refers to an equal byte string; <c>false</c> otherwise.</returns>
+        public bool Equals(ByteString other)
+        {
+            return this == other;
+        }
+
+        /// <summary>
+        /// Copies the entire byte array to the destination array provided at the offset specified.
+        /// </summary>
+        public void CopyTo(byte[] array, int position)
+        {
+            bytes.CopyTo(array.AsMemory(position));
+        }
+
+        /// <summary>
+        /// Writes the entire byte array to the provided stream
+        /// </summary>
+        public void WriteTo(Stream outputStream)
+        {
+            if (MemoryMarshal.TryGetArray(bytes, out ArraySegment<byte> segment))
+            {
+                // Fast path. ByteString was created with an array, so pass the underlying array.
+                outputStream.Write(segment.Array, segment.Offset, segment.Count);
+            }
+            else
+            {
+                // Slow path. BytesString is not an array. Convert memory and pass result to WriteRawBytes.
+                var array = bytes.ToArray();
+                outputStream.Write(array, 0, array.Length);
+            }
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf/ByteStringAsync.cs

@@ -0,0 +1,62 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// SecuritySafeCritical attribute can not be placed on types with async methods.
+    /// This class has ByteString's async methods so it can be marked with SecuritySafeCritical.
+    /// </summary>
+    internal static class ByteStringAsync
+    {
+        internal static async Task<ByteString> FromStreamAsyncCore(Stream stream, CancellationToken cancellationToken)
+        {
+            int capacity = stream.CanSeek ? checked((int)(stream.Length - stream.Position)) : 0;
+            var memoryStream = new MemoryStream(capacity);
+            // We have to specify the buffer size here, as there's no overload accepting the cancellation token
+            // alone. But it's documented to use 81920 by default if not specified.
+            await stream.CopyToAsync(memoryStream, 81920, cancellationToken);
+#if NETSTANDARD1_1
+            byte[] bytes = memoryStream.ToArray();
+#else
+            // Avoid an extra copy if we can.
+            byte[] bytes = memoryStream.Length == memoryStream.Capacity ? memoryStream.GetBuffer() : memoryStream.ToArray();
+#endif
+            return ByteString.AttachBytes(bytes);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf/CodedInputStream.cs

@@ -0,0 +1,680 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using Google.Protobuf.Collections;
+using System;
+using System.IO;
+using System.Security;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Reads and decodes protocol message fields.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// This class is generally used by generated code to read appropriate
+    /// primitives from the stream. It effectively encapsulates the lowest
+    /// levels of protocol buffer format.
+    /// </para>
+    /// <para>
+    /// Repeated fields and map fields are not handled by this class; use <see cref="RepeatedField{T}"/>
+    /// and <see cref="MapField{TKey, TValue}"/> to serialize such fields.
+    /// </para>
+    /// </remarks>
+    [SecuritySafeCritical]
+    public sealed class CodedInputStream : IDisposable
+    {
+        /// <summary>
+        /// Whether to leave the underlying stream open when disposing of this stream.
+        /// This is always true when there's no stream.
+        /// </summary>
+        private readonly bool leaveOpen;
+
+        /// <summary>
+        /// Buffer of data read from the stream or provided at construction time.
+        /// </summary>
+        private readonly byte[] buffer;
+
+        /// <summary>
+        /// The stream to read further input from, or null if the byte array buffer was provided
+        /// directly on construction, with no further data available.
+        /// </summary>
+        private readonly Stream input;
+
+        /// <summary>
+        /// The parser state is kept separately so that other parse implementations can reuse the same
+        /// parsing primitives.
+        /// </summary>
+        private ParserInternalState state;
+
+        internal const int DefaultRecursionLimit = 100;
+        internal const int DefaultSizeLimit = Int32.MaxValue;
+        internal const int BufferSize = 4096;
+
+        #region Construction
+        // Note that the checks are performed such that we don't end up checking obviously-valid things
+        // like non-null references for arrays we've just created.
+
+        /// <summary>
+        /// Creates a new CodedInputStream reading data from the given byte array.
+        /// </summary>
+        public CodedInputStream(byte[] buffer) : this(null, ProtoPreconditions.CheckNotNull(buffer, "buffer"), 0, buffer.Length, true)
+        {            
+        }
+
+        /// <summary>
+        /// Creates a new <see cref="CodedInputStream"/> that reads from the given byte array slice.
+        /// </summary>
+        public CodedInputStream(byte[] buffer, int offset, int length)
+            : this(null, ProtoPreconditions.CheckNotNull(buffer, "buffer"), offset, offset + length, true)
+        {            
+            if (offset < 0 || offset > buffer.Length)
+            {
+                throw new ArgumentOutOfRangeException("offset", "Offset must be within the buffer");
+            }
+            if (length < 0 || offset + length > buffer.Length)
+            {
+                throw new ArgumentOutOfRangeException("length", "Length must be non-negative and within the buffer");
+            }
+        }
+
+        /// <summary>
+        /// Creates a new <see cref="CodedInputStream"/> reading data from the given stream, which will be disposed
+        /// when the returned object is disposed.
+        /// </summary>
+        /// <param name="input">The stream to read from.</param>
+        public CodedInputStream(Stream input) : this(input, false)
+        {
+        }
+
+        /// <summary>
+        /// Creates a new <see cref="CodedInputStream"/> reading data from the given stream.
+        /// </summary>
+        /// <param name="input">The stream to read from.</param>
+        /// <param name="leaveOpen"><c>true</c> to leave <paramref name="input"/> open when the returned
+        /// <c cref="CodedInputStream"/> is disposed; <c>false</c> to dispose of the given stream when the
+        /// returned object is disposed.</param>
+        public CodedInputStream(Stream input, bool leaveOpen)
+            : this(ProtoPreconditions.CheckNotNull(input, "input"), new byte[BufferSize], 0, 0, leaveOpen)
+        {
+        }
+        
+        /// <summary>
+        /// Creates a new CodedInputStream reading data from the given
+        /// stream and buffer, using the default limits.
+        /// </summary>
+        internal CodedInputStream(Stream input, byte[] buffer, int bufferPos, int bufferSize, bool leaveOpen)
+        {
+            this.input = input;
+            this.buffer = buffer;
+            this.state.bufferPos = bufferPos;
+            this.state.bufferSize = bufferSize;
+            this.state.sizeLimit = DefaultSizeLimit;
+            this.state.recursionLimit = DefaultRecursionLimit;
+            SegmentedBufferHelper.Initialize(this, out this.state.segmentedBufferHelper);
+            this.leaveOpen = leaveOpen;
+
+            this.state.currentLimit = int.MaxValue;
+        }
+
+        /// <summary>
+        /// Creates a new CodedInputStream reading data from the given
+        /// stream and buffer, using the specified limits.
+        /// </summary>
+        /// <remarks>
+        /// This chains to the version with the default limits instead of vice versa to avoid
+        /// having to check that the default values are valid every time.
+        /// </remarks>
+        internal CodedInputStream(Stream input, byte[] buffer, int bufferPos, int bufferSize, int sizeLimit, int recursionLimit, bool leaveOpen)
+            : this(input, buffer, bufferPos, bufferSize, leaveOpen)
+        {
+            if (sizeLimit <= 0)
+            {
+                throw new ArgumentOutOfRangeException("sizeLimit", "Size limit must be positive");
+            }
+            if (recursionLimit <= 0)
+            {
+                throw new ArgumentOutOfRangeException("recursionLimit!", "Recursion limit must be positive");
+            }
+            this.state.sizeLimit = sizeLimit;
+            this.state.recursionLimit = recursionLimit;
+        }
+        #endregion
+
+        /// <summary>
+        /// Creates a <see cref="CodedInputStream"/> with the specified size and recursion limits, reading
+        /// from an input stream.
+        /// </summary>
+        /// <remarks>
+        /// This method exists separately from the constructor to reduce the number of constructor overloads.
+        /// It is likely to be used considerably less frequently than the constructors, as the default limits
+        /// are suitable for most use cases.
+        /// </remarks>
+        /// <param name="input">The input stream to read from</param>
+        /// <param name="sizeLimit">The total limit of data to read from the stream.</param>
+        /// <param name="recursionLimit">The maximum recursion depth to allow while reading.</param>
+        /// <returns>A <c>CodedInputStream</c> reading from <paramref name="input"/> with the specified size
+        /// and recursion limits.</returns>
+        public static CodedInputStream CreateWithLimits(Stream input, int sizeLimit, int recursionLimit)
+        {
+            // Note: we may want an overload accepting leaveOpen
+            return new CodedInputStream(input, new byte[BufferSize], 0, 0, sizeLimit, recursionLimit, false);
+        }
+
+        /// <summary>
+        /// Returns the current position in the input stream, or the position in the input buffer
+        /// </summary>
+        public long Position 
+        {
+            get
+            {
+                if (input != null)
+                {
+                    return input.Position - ((state.bufferSize + state.bufferSizeAfterLimit) - state.bufferPos);
+                }
+                return state.bufferPos;
+            }
+        }
+
+        /// <summary>
+        /// Returns the last tag read, or 0 if no tags have been read or we've read beyond
+        /// the end of the stream.
+        /// </summary>
+        internal uint LastTag { get { return state.lastTag; } }
+
+        /// <summary>
+        /// Returns the size limit for this stream.
+        /// </summary>
+        /// <remarks>
+        /// This limit is applied when reading from the underlying stream, as a sanity check. It is
+        /// not applied when reading from a byte array data source without an underlying stream.
+        /// The default value is Int32.MaxValue.
+        /// </remarks>
+        /// <value>
+        /// The size limit.
+        /// </value>
+        public int SizeLimit { get { return state.sizeLimit; } }
+
+        /// <summary>
+        /// Returns the recursion limit for this stream. This limit is applied whilst reading messages,
+        /// to avoid maliciously-recursive data.
+        /// </summary>
+        /// <remarks>
+        /// The default limit is 100.
+        /// </remarks>
+        /// <value>
+        /// The recursion limit for this stream.
+        /// </value>
+        public int RecursionLimit { get { return state.recursionLimit; } }
+
+        /// <summary>
+        /// Internal-only property; when set to true, unknown fields will be discarded while parsing.
+        /// </summary>
+        internal bool DiscardUnknownFields
+        {
+            get { return state.DiscardUnknownFields; }
+            set { state.DiscardUnknownFields = value; }
+        }
+
+        /// <summary>
+        /// Internal-only property; provides extension identifiers to compatible messages while parsing.
+        /// </summary>
+        internal ExtensionRegistry ExtensionRegistry
+        {
+            get { return state.ExtensionRegistry; }
+            set { state.ExtensionRegistry = value; }
+        }
+
+        internal byte[] InternalBuffer => buffer;
+
+        internal Stream InternalInputStream => input;
+
+        internal ref ParserInternalState InternalState => ref state;
+
+        /// <summary>
+        /// Disposes of this instance, potentially closing any underlying stream.
+        /// </summary>
+        /// <remarks>
+        /// As there is no flushing to perform here, disposing of a <see cref="CodedInputStream"/> which
+        /// was constructed with the <c>leaveOpen</c> option parameter set to <c>true</c> (or one which
+        /// was constructed to read from a byte array) has no effect.
+        /// </remarks>
+        public void Dispose()
+        {
+            if (!leaveOpen)
+            {
+                input.Dispose();
+            }
+        }
+
+        #region Validation
+        /// <summary>
+        /// Verifies that the last call to ReadTag() returned tag 0 - in other words,
+        /// we've reached the end of the stream when we expected to.
+        /// </summary>
+        /// <exception cref="InvalidProtocolBufferException">The 
+        /// tag read was not the one specified</exception>
+        internal void CheckReadEndOfStreamTag()
+        {
+            ParsingPrimitivesMessages.CheckReadEndOfStreamTag(ref state);
+        }
+        #endregion
+
+        #region Reading of tags etc
+
+        /// <summary>
+        /// Peeks at the next field tag. This is like calling <see cref="ReadTag"/>, but the
+        /// tag is not consumed. (So a subsequent call to <see cref="ReadTag"/> will return the
+        /// same value.)
+        /// </summary>
+        public uint PeekTag()
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            return ParsingPrimitives.PeekTag(ref span, ref state);
+        }
+
+        /// <summary>
+        /// Reads a field tag, returning the tag of 0 for "end of stream".
+        /// </summary>
+        /// <remarks>
+        /// If this method returns 0, it doesn't necessarily mean the end of all
+        /// the data in this CodedInputStream; it may be the end of the logical stream
+        /// for an embedded message, for example.
+        /// </remarks>
+        /// <returns>The next field tag, or 0 for end of stream. (0 is never a valid tag.)</returns>
+        public uint ReadTag()
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            return ParsingPrimitives.ParseTag(ref span, ref state);
+        }
+
+        /// <summary>
+        /// Skips the data for the field with the tag we've just read.
+        /// This should be called directly after <see cref="ReadTag"/>, when
+        /// the caller wishes to skip an unknown field.
+        /// </summary>
+        /// <remarks>
+        /// This method throws <see cref="InvalidProtocolBufferException"/> if the last-read tag was an end-group tag.
+        /// If a caller wishes to skip a group, they should skip the whole group, by calling this method after reading the
+        /// start-group tag. This behavior allows callers to call this method on any field they don't understand, correctly
+        /// resulting in an error if an end-group tag has not been paired with an earlier start-group tag.
+        /// </remarks>
+        /// <exception cref="InvalidProtocolBufferException">The last tag was an end-group tag</exception>
+        /// <exception cref="InvalidOperationException">The last read operation read to the end of the logical stream</exception>
+        public void SkipLastField()
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            ParsingPrimitivesMessages.SkipLastField(ref span, ref state);
+        }
+
+        /// <summary>
+        /// Skip a group.
+        /// </summary>
+        internal void SkipGroup(uint startGroupTag)
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            ParsingPrimitivesMessages.SkipGroup(ref span, ref state, startGroupTag);
+        }
+
+        /// <summary>
+        /// Reads a double field from the stream.
+        /// </summary>
+        public double ReadDouble()
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            return ParsingPrimitives.ParseDouble(ref span, ref state);
+        }
+
+        /// <summary>
+        /// Reads a float field from the stream.
+        /// </summary>
+        public float ReadFloat()
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            return ParsingPrimitives.ParseFloat(ref span, ref state);
+        }
+
+        /// <summary>
+        /// Reads a uint64 field from the stream.
+        /// </summary>
+        public ulong ReadUInt64()
+        {
+            return ReadRawVarint64();
+        }
+
+        /// <summary>
+        /// Reads an int64 field from the stream.
+        /// </summary>
+        public long ReadInt64()
+        {
+            return (long) ReadRawVarint64();
+        }
+
+        /// <summary>
+        /// Reads an int32 field from the stream.
+        /// </summary>
+        public int ReadInt32()
+        {
+            return (int) ReadRawVarint32();
+        }
+
+        /// <summary>
+        /// Reads a fixed64 field from the stream.
+        /// </summary>
+        public ulong ReadFixed64()
+        {
+            return ReadRawLittleEndian64();
+        }
+
+        /// <summary>
+        /// Reads a fixed32 field from the stream.
+        /// </summary>
+        public uint ReadFixed32()
+        {
+            return ReadRawLittleEndian32();
+        }
+
+        /// <summary>
+        /// Reads a bool field from the stream.
+        /// </summary>
+        public bool ReadBool()
+        {
+            return ReadRawVarint64() != 0;
+        }
+
+        /// <summary>
+        /// Reads a string field from the stream.
+        /// </summary>
+        public string ReadString()
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            return ParsingPrimitives.ReadString(ref span, ref state);
+        }
+
+        /// <summary>
+        /// Reads an embedded message field value from the stream.
+        /// </summary>
+        public void ReadMessage(IMessage builder)
+        {
+            // TODO(jtattermusch): if the message doesn't implement IBufferMessage (and thus does not provide the InternalMergeFrom method),
+            // what we're doing here works fine, but could be more efficient.
+            // What happens is that we first initialize a ParseContext from the current coded input stream only to parse the length of the message, at which point
+            // we will need to switch back again to CodedInputStream-based parsing (which involves copying and storing the state) to be able to
+            // invoke the legacy MergeFrom(CodedInputStream) method.
+            // For now, this inefficiency is fine, considering this is only a backward-compatibility scenario (and regenerating the code fixes it).
+            ParseContext.Initialize(buffer.AsSpan(), ref state, out ParseContext ctx);
+            try
+            {
+                ParsingPrimitivesMessages.ReadMessage(ref ctx, builder);
+            }
+            finally
+            {
+                ctx.CopyStateTo(this);
+            }
+        }
+
+        /// <summary>
+        /// Reads an embedded group field from the stream.
+        /// </summary>
+        public void ReadGroup(IMessage builder)
+        {
+            ParseContext.Initialize(this, out ParseContext ctx);
+            try
+            {
+                ParsingPrimitivesMessages.ReadGroup(ref ctx, builder);
+            }
+            finally
+            {
+                ctx.CopyStateTo(this);
+            }
+        }
+
+        /// <summary>
+        /// Reads a bytes field value from the stream.
+        /// </summary>   
+        public ByteString ReadBytes()
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            return ParsingPrimitives.ReadBytes(ref span, ref state);
+        }
+
+        /// <summary>
+        /// Reads a uint32 field value from the stream.
+        /// </summary>   
+        public uint ReadUInt32()
+        {
+            return ReadRawVarint32();
+        }
+
+        /// <summary>
+        /// Reads an enum field value from the stream.
+        /// </summary>   
+        public int ReadEnum()
+        {
+            // Currently just a pass-through, but it's nice to separate it logically from WriteInt32.
+            return (int) ReadRawVarint32();
+        }
+
+        /// <summary>
+        /// Reads an sfixed32 field value from the stream.
+        /// </summary>   
+        public int ReadSFixed32()
+        {
+            return (int) ReadRawLittleEndian32();
+        }
+
+        /// <summary>
+        /// Reads an sfixed64 field value from the stream.
+        /// </summary>   
+        public long ReadSFixed64()
+        {
+            return (long) ReadRawLittleEndian64();
+        }
+
+        /// <summary>
+        /// Reads an sint32 field value from the stream.
+        /// </summary>   
+        public int ReadSInt32()
+        {
+            return ParsingPrimitives.DecodeZigZag32(ReadRawVarint32());
+        }
+
+        /// <summary>
+        /// Reads an sint64 field value from the stream.
+        /// </summary>   
+        public long ReadSInt64()
+        {
+            return ParsingPrimitives.DecodeZigZag64(ReadRawVarint64());
+        }
+
+        /// <summary>
+        /// Reads a length for length-delimited data.
+        /// </summary>
+        /// <remarks>
+        /// This is internally just reading a varint, but this method exists
+        /// to make the calling code clearer.
+        /// </remarks>
+        public int ReadLength()
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            return ParsingPrimitives.ParseLength(ref span, ref state);
+        }
+
+        /// <summary>
+        /// Peeks at the next tag in the stream. If it matches <paramref name="tag"/>,
+        /// the tag is consumed and the method returns <c>true</c>; otherwise, the
+        /// stream is left in the original position and the method returns <c>false</c>.
+        /// </summary>
+        public bool MaybeConsumeTag(uint tag)
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            return ParsingPrimitives.MaybeConsumeTag(ref span, ref state, tag);
+        }
+
+#endregion
+
+        #region Underlying reading primitives
+
+        /// <summary>
+        /// Reads a raw Varint from the stream.  If larger than 32 bits, discard the upper bits.
+        /// This method is optimised for the case where we've got lots of data in the buffer.
+        /// That means we can check the size just once, then just read directly from the buffer
+        /// without constant rechecking of the buffer length.
+        /// </summary>
+        internal uint ReadRawVarint32()
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            return ParsingPrimitives.ParseRawVarint32(ref span, ref state);
+        }
+
+        /// <summary>
+        /// Reads a varint from the input one byte at a time, so that it does not
+        /// read any bytes after the end of the varint. If you simply wrapped the
+        /// stream in a CodedInputStream and used ReadRawVarint32(Stream)
+        /// then you would probably end up reading past the end of the varint since
+        /// CodedInputStream buffers its input.
+        /// </summary>
+        /// <param name="input"></param>
+        /// <returns></returns>
+        internal static uint ReadRawVarint32(Stream input)
+        {
+            return ParsingPrimitives.ReadRawVarint32(input);
+        }
+
+        /// <summary>
+        /// Reads a raw varint from the stream.
+        /// </summary>
+        internal ulong ReadRawVarint64()
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            return ParsingPrimitives.ParseRawVarint64(ref span, ref state);
+        }
+
+        /// <summary>
+        /// Reads a 32-bit little-endian integer from the stream.
+        /// </summary>
+        internal uint ReadRawLittleEndian32()
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            return ParsingPrimitives.ParseRawLittleEndian32(ref span, ref state);
+        }
+
+        /// <summary>
+        /// Reads a 64-bit little-endian integer from the stream.
+        /// </summary>
+        internal ulong ReadRawLittleEndian64()
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            return ParsingPrimitives.ParseRawLittleEndian64(ref span, ref state);
+        }
+        #endregion
+
+        #region Internal reading and buffer management
+
+        /// <summary>
+        /// Sets currentLimit to (current position) + byteLimit. This is called
+        /// when descending into a length-delimited embedded message. The previous
+        /// limit is returned.
+        /// </summary>
+        /// <returns>The old limit.</returns>
+        internal int PushLimit(int byteLimit)
+        {
+            return SegmentedBufferHelper.PushLimit(ref state, byteLimit);
+        }
+
+        /// <summary>
+        /// Discards the current limit, returning the previous limit.
+        /// </summary>
+        internal void PopLimit(int oldLimit)
+        {
+            SegmentedBufferHelper.PopLimit(ref state, oldLimit);
+        }
+
+        /// <summary>
+        /// Returns whether or not all the data before the limit has been read.
+        /// </summary>
+        /// <returns></returns>
+        internal bool ReachedLimit
+        {
+            get
+            {
+                return SegmentedBufferHelper.IsReachedLimit(ref state);
+            }
+        }
+
+        /// <summary>
+        /// Returns true if the stream has reached the end of the input. This is the
+        /// case if either the end of the underlying input source has been reached or
+        /// the stream has reached a limit created using PushLimit.
+        /// </summary>
+        public bool IsAtEnd
+        {
+            get
+            {
+                var span = new ReadOnlySpan<byte>(buffer);
+                return SegmentedBufferHelper.IsAtEnd(ref span, ref state);
+            }
+        }
+
+        /// <summary>
+        /// Reads a fixed size of bytes from the input.
+        /// </summary>
+        /// <exception cref="InvalidProtocolBufferException">
+        /// the end of the stream or the current limit was reached
+        /// </exception>
+        internal byte[] ReadRawBytes(int size)
+        {
+            var span = new ReadOnlySpan<byte>(buffer);
+            return ParsingPrimitives.ReadRawBytes(ref span, ref state, size);
+        }
+
+        /// <summary>
+        /// Reads a top-level message or a nested message after the limits for this message have been pushed.
+        /// (parser will proceed until the end of the current limit)
+        /// NOTE: this method needs to be public because it's invoked by the generated code - e.g. msg.MergeFrom(CodedInputStream input) method
+        /// </summary>
+        public void ReadRawMessage(IMessage message)
+        {
+            ParseContext.Initialize(this, out ParseContext ctx);
+            try
+            {
+                ParsingPrimitivesMessages.ReadRawMessage(ref ctx, message);
+            }
+            finally
+            {
+                ctx.CopyStateTo(this);
+            }
+        }
+#endregion
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf/CodedOutputStream.ComputeSize.cs

@@ -0,0 +1,308 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+
+namespace Google.Protobuf
+{
+    // This part of CodedOutputStream provides all the static entry points that are used
+    // by generated code and internally to compute the size of messages prior to being
+    // written to an instance of CodedOutputStream.
+    public sealed partial class CodedOutputStream
+    {
+        private const int LittleEndian64Size = 8;
+        private const int LittleEndian32Size = 4;        
+
+        internal const int DoubleSize = LittleEndian64Size;
+        internal const int FloatSize = LittleEndian32Size;
+        internal const int BoolSize = 1;
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a
+        /// double field, including the tag.
+        /// </summary>
+        public static int ComputeDoubleSize(double value)
+        {
+            return DoubleSize;
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a
+        /// float field, including the tag.
+        /// </summary>
+        public static int ComputeFloatSize(float value)
+        {
+            return FloatSize;
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a
+        /// uint64 field, including the tag.
+        /// </summary>
+        public static int ComputeUInt64Size(ulong value)
+        {
+            return ComputeRawVarint64Size(value);
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode an
+        /// int64 field, including the tag.
+        /// </summary>
+        public static int ComputeInt64Size(long value)
+        {
+            return ComputeRawVarint64Size((ulong) value);
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode an
+        /// int32 field, including the tag.
+        /// </summary>
+        public static int ComputeInt32Size(int value)
+        {
+            if (value >= 0)
+            {
+                return ComputeRawVarint32Size((uint) value);
+            }
+            else
+            {
+                // Must sign-extend.
+                return 10;
+            }
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a
+        /// fixed64 field, including the tag.
+        /// </summary>
+        public static int ComputeFixed64Size(ulong value)
+        {
+            return LittleEndian64Size;
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a
+        /// fixed32 field, including the tag.
+        /// </summary>
+        public static int ComputeFixed32Size(uint value)
+        {
+            return LittleEndian32Size;
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a
+        /// bool field, including the tag.
+        /// </summary>
+        public static int ComputeBoolSize(bool value)
+        {
+            return BoolSize;
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a
+        /// string field, including the tag.
+        /// </summary>
+        public static int ComputeStringSize(String value)
+        {
+            int byteArraySize = WritingPrimitives.Utf8Encoding.GetByteCount(value);
+            return ComputeLengthSize(byteArraySize) + byteArraySize;
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a
+        /// group field, including the tag.
+        /// </summary>
+        public static int ComputeGroupSize(IMessage value)
+        {
+            return value.CalculateSize();
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode an
+        /// embedded message field, including the tag.
+        /// </summary>
+        public static int ComputeMessageSize(IMessage value)
+        {
+            int size = value.CalculateSize();
+            return ComputeLengthSize(size) + size;
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a
+        /// bytes field, including the tag.
+        /// </summary>
+        public static int ComputeBytesSize(ByteString value)
+        {
+            return ComputeLengthSize(value.Length) + value.Length;
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a
+        /// uint32 field, including the tag.
+        /// </summary>
+        public static int ComputeUInt32Size(uint value)
+        {
+            return ComputeRawVarint32Size(value);
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a
+        /// enum field, including the tag. The caller is responsible for
+        /// converting the enum value to its numeric value.
+        /// </summary>
+        public static int ComputeEnumSize(int value)
+        {
+            // Currently just a pass-through, but it's nice to separate it logically.
+            return ComputeInt32Size(value);
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode an
+        /// sfixed32 field, including the tag.
+        /// </summary>
+        public static int ComputeSFixed32Size(int value)
+        {
+            return LittleEndian32Size;
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode an
+        /// sfixed64 field, including the tag.
+        /// </summary>
+        public static int ComputeSFixed64Size(long value)
+        {
+            return LittleEndian64Size;
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode an
+        /// sint32 field, including the tag.
+        /// </summary>
+        public static int ComputeSInt32Size(int value)
+        {
+            return ComputeRawVarint32Size(WritingPrimitives.EncodeZigZag32(value));
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode an
+        /// sint64 field, including the tag.
+        /// </summary>
+        public static int ComputeSInt64Size(long value)
+        {
+            return ComputeRawVarint64Size(WritingPrimitives.EncodeZigZag64(value));
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a length,
+        /// as written by <see cref="WriteLength"/>.
+        /// </summary>
+        public static int ComputeLengthSize(int length)
+        {
+            return ComputeRawVarint32Size((uint) length);
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a varint.
+        /// </summary>
+        public static int ComputeRawVarint32Size(uint value)
+        {
+            if ((value & (0xffffffff << 7)) == 0)
+            {
+                return 1;
+            }
+            if ((value & (0xffffffff << 14)) == 0)
+            {
+                return 2;
+            }
+            if ((value & (0xffffffff << 21)) == 0)
+            {
+                return 3;
+            }
+            if ((value & (0xffffffff << 28)) == 0)
+            {
+                return 4;
+            }
+            return 5;
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a varint.
+        /// </summary>
+        public static int ComputeRawVarint64Size(ulong value)
+        {
+            if ((value & (0xffffffffffffffffL << 7)) == 0)
+            {
+                return 1;
+            }
+            if ((value & (0xffffffffffffffffL << 14)) == 0)
+            {
+                return 2;
+            }
+            if ((value & (0xffffffffffffffffL << 21)) == 0)
+            {
+                return 3;
+            }
+            if ((value & (0xffffffffffffffffL << 28)) == 0)
+            {
+                return 4;
+            }
+            if ((value & (0xffffffffffffffffL << 35)) == 0)
+            {
+                return 5;
+            }
+            if ((value & (0xffffffffffffffffL << 42)) == 0)
+            {
+                return 6;
+            }
+            if ((value & (0xffffffffffffffffL << 49)) == 0)
+            {
+                return 7;
+            }
+            if ((value & (0xffffffffffffffffL << 56)) == 0)
+            {
+                return 8;
+            }
+            if ((value & (0xffffffffffffffffL << 63)) == 0)
+            {
+                return 9;
+            }
+            return 10;
+        }
+
+        /// <summary>
+        /// Computes the number of bytes that would be needed to encode a tag.
+        /// </summary>
+        public static int ComputeTagSize(int fieldNumber)
+        {
+            return ComputeRawVarint32Size(WireFormat.MakeTag(fieldNumber, 0));
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf/CodedOutputStream.cs

@@ -0,0 +1,605 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.IO;
+using System.Security;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Encodes and writes protocol message fields.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// This class is generally used by generated code to write appropriate
+    /// primitives to the stream. It effectively encapsulates the lowest
+    /// levels of protocol buffer format. Unlike some other implementations,
+    /// this does not include combined "write tag and value" methods. Generated
+    /// code knows the exact byte representations of the tags they're going to write,
+    /// so there's no need to re-encode them each time. Manually-written code calling
+    /// this class should just call one of the <c>WriteTag</c> overloads before each value.
+    /// </para>
+    /// <para>
+    /// Repeated fields and map fields are not handled by this class; use <c>RepeatedField&lt;T&gt;</c>
+    /// and <c>MapField&lt;TKey, TValue&gt;</c> to serialize such fields.
+    /// </para>
+    /// </remarks>
+    [SecuritySafeCritical]
+    public sealed partial class CodedOutputStream : IDisposable
+    {
+        /// <summary>
+        /// The buffer size used by CreateInstance(Stream).
+        /// </summary>
+        public static readonly int DefaultBufferSize = 4096;
+
+        private readonly bool leaveOpen;
+        private readonly byte[] buffer;
+        private WriterInternalState state;
+
+        private readonly Stream output;
+
+        #region Construction
+        /// <summary>
+        /// Creates a new CodedOutputStream that writes directly to the given
+        /// byte array. If more bytes are written than fit in the array,
+        /// OutOfSpaceException will be thrown.
+        /// </summary>
+        public CodedOutputStream(byte[] flatArray) : this(flatArray, 0, flatArray.Length)
+        {
+        }
+
+        /// <summary>
+        /// Creates a new CodedOutputStream that writes directly to the given
+        /// byte array slice. If more bytes are written than fit in the array,
+        /// OutOfSpaceException will be thrown.
+        /// </summary>
+        private CodedOutputStream(byte[] buffer, int offset, int length)
+        {
+            this.output = null;
+            this.buffer = ProtoPreconditions.CheckNotNull(buffer, nameof(buffer));
+            this.state.position = offset;
+            this.state.limit = offset + length;
+            WriteBufferHelper.Initialize(this, out this.state.writeBufferHelper);
+            leaveOpen = true; // Simple way of avoiding trying to dispose of a null reference
+        }
+
+        private CodedOutputStream(Stream output, byte[] buffer, bool leaveOpen)
+        {
+            this.output = ProtoPreconditions.CheckNotNull(output, nameof(output));
+            this.buffer = buffer;
+            this.state.position = 0;
+            this.state.limit = buffer.Length;
+            WriteBufferHelper.Initialize(this, out this.state.writeBufferHelper);
+            this.leaveOpen = leaveOpen;
+        }
+
+        /// <summary>
+        /// Creates a new <see cref="CodedOutputStream" /> which write to the given stream, and disposes of that
+        /// stream when the returned <c>CodedOutputStream</c> is disposed.
+        /// </summary>
+        /// <param name="output">The stream to write to. It will be disposed when the returned <c>CodedOutputStream is disposed.</c></param>
+        public CodedOutputStream(Stream output) : this(output, DefaultBufferSize, false)
+        {
+        }
+
+        /// <summary>
+        /// Creates a new CodedOutputStream which write to the given stream and uses
+        /// the specified buffer size.
+        /// </summary>
+        /// <param name="output">The stream to write to. It will be disposed when the returned <c>CodedOutputStream is disposed.</c></param>
+        /// <param name="bufferSize">The size of buffer to use internally.</param>
+        public CodedOutputStream(Stream output, int bufferSize) : this(output, new byte[bufferSize], false)
+        {
+        }
+
+        /// <summary>
+        /// Creates a new CodedOutputStream which write to the given stream.
+        /// </summary>
+        /// <param name="output">The stream to write to.</param>
+        /// <param name="leaveOpen">If <c>true</c>, <paramref name="output"/> is left open when the returned <c>CodedOutputStream</c> is disposed;
+        /// if <c>false</c>, the provided stream is disposed as well.</param>
+        public CodedOutputStream(Stream output, bool leaveOpen) : this(output, DefaultBufferSize, leaveOpen)
+        {
+        }
+
+        /// <summary>
+        /// Creates a new CodedOutputStream which write to the given stream and uses
+        /// the specified buffer size.
+        /// </summary>
+        /// <param name="output">The stream to write to.</param>
+        /// <param name="bufferSize">The size of buffer to use internally.</param>
+        /// <param name="leaveOpen">If <c>true</c>, <paramref name="output"/> is left open when the returned <c>CodedOutputStream</c> is disposed;
+        /// if <c>false</c>, the provided stream is disposed as well.</param>
+        public CodedOutputStream(Stream output, int bufferSize, bool leaveOpen) : this(output, new byte[bufferSize], leaveOpen)
+        {
+        }
+        #endregion
+
+        /// <summary>
+        /// Returns the current position in the stream, or the position in the output buffer
+        /// </summary>
+        public long Position
+        {
+            get
+            {
+                if (output != null)
+                {
+                    return output.Position + state.position;
+                }
+                return state.position;
+            }
+        }
+
+        #region Writing of values (not including tags)
+
+        /// <summary>
+        /// Writes a double field value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteDouble(double value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteDouble(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes a float field value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteFloat(float value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteFloat(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes a uint64 field value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteUInt64(ulong value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteUInt64(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes an int64 field value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteInt64(long value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteInt64(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes an int32 field value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteInt32(int value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteInt32(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes a fixed64 field value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteFixed64(ulong value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteFixed64(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes a fixed32 field value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteFixed32(uint value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteFixed32(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes a bool field value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteBool(bool value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteBool(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes a string field value, without a tag, to the stream.
+        /// The data is length-prefixed.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteString(string value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteString(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes a message, without a tag, to the stream.
+        /// The data is length-prefixed.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteMessage(IMessage value)
+        {
+            // TODO(jtattermusch): if the message doesn't implement IBufferMessage (and thus does not provide the InternalWriteTo method),
+            // what we're doing here works fine, but could be more efficient.
+            // For now, this inefficiency is fine, considering this is only a backward-compatibility scenario (and regenerating the code fixes it).
+            var span = new Span<byte>(buffer);
+            WriteContext.Initialize(ref span, ref state, out WriteContext ctx);
+            try
+            {
+                WritingPrimitivesMessages.WriteMessage(ref ctx, value);
+            }
+            finally
+            {
+                ctx.CopyStateTo(this);
+            }
+        }
+
+        /// <summary>
+        /// Writes a message, without a tag, to the stream.
+        /// Only the message data is written, without a length-delimiter.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteRawMessage(IMessage value)
+        {
+            // TODO(jtattermusch): if the message doesn't implement IBufferMessage (and thus does not provide the InternalWriteTo method),
+            // what we're doing here works fine, but could be more efficient.
+            // For now, this inefficiency is fine, considering this is only a backward-compatibility scenario (and regenerating the code fixes it).
+            var span = new Span<byte>(buffer);
+            WriteContext.Initialize(ref span, ref state, out WriteContext ctx);
+            try
+            {
+                WritingPrimitivesMessages.WriteRawMessage(ref ctx, value);
+            }
+            finally
+            {
+                ctx.CopyStateTo(this);
+            }
+        }
+
+        /// <summary>
+        /// Writes a group, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteGroup(IMessage value)
+        {
+            var span = new Span<byte>(buffer);
+            WriteContext.Initialize(ref span, ref state, out WriteContext ctx);
+            try
+            {
+                WritingPrimitivesMessages.WriteGroup(ref ctx, value);
+            }
+            finally
+            {
+                ctx.CopyStateTo(this);
+            }
+        }
+
+        /// <summary>
+        /// Write a byte string, without a tag, to the stream.
+        /// The data is length-prefixed.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteBytes(ByteString value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteBytes(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes a uint32 value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteUInt32(uint value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteUInt32(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes an enum value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteEnum(int value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteEnum(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes an sfixed32 value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write.</param>
+        public void WriteSFixed32(int value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteSFixed32(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes an sfixed64 value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteSFixed64(long value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteSFixed64(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes an sint32 value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteSInt32(int value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteSInt32(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes an sint64 value, without a tag, to the stream.
+        /// </summary>
+        /// <param name="value">The value to write</param>
+        public void WriteSInt64(long value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteSInt64(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes a length (in bytes) for length-delimited data.
+        /// </summary>
+        /// <remarks>
+        /// This method simply writes a rawint, but exists for clarity in calling code.
+        /// </remarks>
+        /// <param name="length">Length value, in bytes.</param>
+        public void WriteLength(int length)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteLength(ref span, ref state, length);
+        }
+
+        #endregion
+
+        #region Raw tag writing
+        /// <summary>
+        /// Encodes and writes a tag.
+        /// </summary>
+        /// <param name="fieldNumber">The number of the field to write the tag for</param>
+        /// <param name="type">The wire format type of the tag to write</param>
+        public void WriteTag(int fieldNumber, WireFormat.WireType type)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteTag(ref span, ref state, fieldNumber, type);
+        }
+
+        /// <summary>
+        /// Writes an already-encoded tag.
+        /// </summary>
+        /// <param name="tag">The encoded tag</param>
+        public void WriteTag(uint tag)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteTag(ref span, ref state, tag);
+        }
+
+        /// <summary>
+        /// Writes the given single-byte tag directly to the stream.
+        /// </summary>
+        /// <param name="b1">The encoded tag</param>
+        public void WriteRawTag(byte b1)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteRawTag(ref span, ref state, b1);
+        }
+
+        /// <summary>
+        /// Writes the given two-byte tag directly to the stream.
+        /// </summary>
+        /// <param name="b1">The first byte of the encoded tag</param>
+        /// <param name="b2">The second byte of the encoded tag</param>
+        public void WriteRawTag(byte b1, byte b2)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteRawTag(ref span, ref state, b1, b2);
+        }
+
+        /// <summary>
+        /// Writes the given three-byte tag directly to the stream.
+        /// </summary>
+        /// <param name="b1">The first byte of the encoded tag</param>
+        /// <param name="b2">The second byte of the encoded tag</param>
+        /// <param name="b3">The third byte of the encoded tag</param>
+        public void WriteRawTag(byte b1, byte b2, byte b3)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteRawTag(ref span, ref state, b1, b2, b3);
+        }
+
+        /// <summary>
+        /// Writes the given four-byte tag directly to the stream.
+        /// </summary>
+        /// <param name="b1">The first byte of the encoded tag</param>
+        /// <param name="b2">The second byte of the encoded tag</param>
+        /// <param name="b3">The third byte of the encoded tag</param>
+        /// <param name="b4">The fourth byte of the encoded tag</param>
+        public void WriteRawTag(byte b1, byte b2, byte b3, byte b4)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteRawTag(ref span, ref state, b1, b2, b3, b4);
+        }
+
+        /// <summary>
+        /// Writes the given five-byte tag directly to the stream.
+        /// </summary>
+        /// <param name="b1">The first byte of the encoded tag</param>
+        /// <param name="b2">The second byte of the encoded tag</param>
+        /// <param name="b3">The third byte of the encoded tag</param>
+        /// <param name="b4">The fourth byte of the encoded tag</param>
+        /// <param name="b5">The fifth byte of the encoded tag</param>
+        public void WriteRawTag(byte b1, byte b2, byte b3, byte b4, byte b5)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteRawTag(ref span, ref state, b1, b2, b3, b4, b5);
+        }
+        #endregion
+
+        #region Underlying writing primitives
+        
+        /// <summary>
+        /// Writes a 32 bit value as a varint. The fast route is taken when
+        /// there's enough buffer space left to whizz through without checking
+        /// for each byte; otherwise, we resort to calling WriteRawByte each time.
+        /// </summary>
+        internal void WriteRawVarint32(uint value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteRawVarint32(ref span, ref state, value);
+        }
+
+        internal void WriteRawVarint64(ulong value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteRawVarint64(ref span, ref state, value);
+        }
+
+        internal void WriteRawLittleEndian32(uint value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteRawLittleEndian32(ref span, ref state, value);
+        }
+
+        internal void WriteRawLittleEndian64(ulong value)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteRawLittleEndian64(ref span, ref state, value);
+        }
+
+        /// <summary>
+        /// Writes out an array of bytes.
+        /// </summary>
+        internal void WriteRawBytes(byte[] value)
+        {
+            WriteRawBytes(value, 0, value.Length);
+        }
+
+        /// <summary>
+        /// Writes out part of an array of bytes.
+        /// </summary>
+        internal void WriteRawBytes(byte[] value, int offset, int length)
+        {
+            var span = new Span<byte>(buffer);
+            WritingPrimitives.WriteRawBytes(ref span, ref state, value, offset, length);
+        }
+
+        #endregion
+
+        /// <summary>
+        /// Indicates that a CodedOutputStream wrapping a flat byte array
+        /// ran out of space.
+        /// </summary>
+        public sealed class OutOfSpaceException : IOException
+        {
+            internal OutOfSpaceException()
+                : base("CodedOutputStream was writing to a flat byte array and ran out of space.")
+            {
+            }
+        }
+
+        /// <summary>
+        /// Flushes any buffered data and optionally closes the underlying stream, if any.
+        /// </summary>
+        /// <remarks>
+        /// <para>
+        /// By default, any underlying stream is closed by this method. To configure this behaviour,
+        /// use a constructor overload with a <c>leaveOpen</c> parameter. If this instance does not
+        /// have an underlying stream, this method does nothing.
+        /// </para>
+        /// <para>
+        /// For the sake of efficiency, calling this method does not prevent future write calls - but
+        /// if a later write ends up writing to a stream which has been disposed, that is likely to
+        /// fail. It is recommend that you not call any other methods after this.
+        /// </para>
+        /// </remarks>
+        public void Dispose()
+        {
+            Flush();
+            if (!leaveOpen)
+            {
+                output.Dispose();
+            }
+        }
+
+        /// <summary>
+        /// Flushes any buffered data to the underlying stream (if there is one).
+        /// </summary>
+        public void Flush()
+        {
+            var span = new Span<byte>(buffer);
+            WriteBufferHelper.Flush(ref span, ref state);
+        }
+
+        /// <summary>
+        /// Verifies that SpaceLeft returns zero. It's common to create a byte array
+        /// that is exactly big enough to hold a message, then write to it with
+        /// a CodedOutputStream. Calling CheckNoSpaceLeft after writing verifies that
+        /// the message was actually as big as expected, which can help finding bugs.
+        /// </summary>
+        public void CheckNoSpaceLeft()
+        {
+            WriteBufferHelper.CheckNoSpaceLeft(ref state);
+        }
+
+        /// <summary>
+        /// If writing to a flat array, returns the space left in the array. Otherwise,
+        /// throws an InvalidOperationException.
+        /// </summary>
+        public int SpaceLeft => WriteBufferHelper.GetSpaceLeft(ref state);
+
+        internal byte[] InternalBuffer => buffer;
+
+        internal Stream InternalOutputStream => output;
+
+        internal ref WriterInternalState InternalState => ref state;
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf/Collections/Lists.cs

@@ -0,0 +1,88 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2017 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System.Collections.Generic;
+
+namespace Google.Protobuf.Collections
+{
+    /// <summary>
+    /// Utility to compare if two Lists are the same, and the hash code
+    /// of a List.
+    /// </summary>
+    public static class Lists
+    {
+        /// <summary>
+        /// Checks if two lists are equal.
+        /// </summary>
+        public static bool Equals<T>(List<T> left, List<T> right)
+        {
+            if (left == right)
+            {
+                return true;
+            }
+            if (left == null || right == null)
+            {
+                return false;
+            }
+            if (left.Count != right.Count)
+            {
+                return false;
+            }
+            IEqualityComparer<T> comparer = EqualityComparer<T>.Default;
+            for (int i = 0; i < left.Count; i++)
+            {
+                if (!comparer.Equals(left[i], right[i]))
+                {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        /// <summary>
+        /// Gets the list's hash code.
+        /// </summary>
+        public static int GetHashCode<T>(List<T> list)
+        {
+            if (list == null)
+            {
+                return 0;
+            }
+            int hash = 31;
+            foreach (T element in list)
+            {
+                hash = hash * 29 + element.GetHashCode();
+            }
+            return hash;
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf/Collections/MapField.cs

@@ -0,0 +1,710 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using Google.Protobuf.Compatibility;
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Security;
+
+namespace Google.Protobuf.Collections
+{
+    /// <summary>
+    /// Representation of a map field in a Protocol Buffer message.
+    /// </summary>
+    /// <typeparam name="TKey">Key type in the map. Must be a type supported by Protocol Buffer map keys.</typeparam>
+    /// <typeparam name="TValue">Value type in the map. Must be a type supported by Protocol Buffers.</typeparam>
+    /// <remarks>
+    /// <para>
+    /// For string keys, the equality comparison is provided by <see cref="StringComparer.Ordinal" />.
+    /// </para>
+    /// <para>
+    /// Null values are not permitted in the map, either for wrapper types or regular messages.
+    /// If a map is deserialized from a data stream and the value is missing from an entry, a default value
+    /// is created instead. For primitive types, that is the regular default value (0, the empty string and so
+    /// on); for message types, an empty instance of the message is created, as if the map entry contained a 0-length
+    /// encoded value for the field.
+    /// </para>
+    /// <para>
+    /// This implementation does not generally prohibit the use of key/value types which are not
+    /// supported by Protocol Buffers (e.g. using a key type of <code>byte</code>) but nor does it guarantee
+    /// that all operations will work in such cases.
+    /// </para>
+    /// <para>
+    /// The order in which entries are returned when iterating over this object is undefined, and may change
+    /// in future versions.
+    /// </para>
+    /// </remarks>
+    public sealed class MapField<TKey, TValue> : IDeepCloneable<MapField<TKey, TValue>>, IDictionary<TKey, TValue>, IEquatable<MapField<TKey, TValue>>, IDictionary, IReadOnlyDictionary<TKey, TValue>
+    {
+        private static readonly EqualityComparer<TValue> ValueEqualityComparer = ProtobufEqualityComparers.GetEqualityComparer<TValue>();
+        private static readonly EqualityComparer<TKey> KeyEqualityComparer = ProtobufEqualityComparers.GetEqualityComparer<TKey>();
+
+        // TODO: Don't create the map/list until we have an entry. (Assume many maps will be empty.)
+        private readonly Dictionary<TKey, LinkedListNode<KeyValuePair<TKey, TValue>>> map = new(KeyEqualityComparer);
+        private readonly LinkedList<KeyValuePair<TKey, TValue>> list = new();
+
+        /// <summary>
+        /// Creates a deep clone of this object.
+        /// </summary>
+        /// <returns>
+        /// A deep clone of this object.
+        /// </returns>
+        public MapField<TKey, TValue> Clone()
+        {
+            var clone = new MapField<TKey, TValue>();
+            // Keys are never cloneable. Values might be.
+            if (typeof(IDeepCloneable<TValue>).IsAssignableFrom(typeof(TValue)))
+            {
+                foreach (var pair in list)
+                {
+                    clone.Add(pair.Key, ((IDeepCloneable<TValue>)pair.Value).Clone());
+                }
+            }
+            else
+            {
+                // Nothing is cloneable, so we don't need to worry.
+                clone.Add(this);
+            }
+            return clone;
+        }
+
+        /// <summary>
+        /// Adds the specified key/value pair to the map.
+        /// </summary>
+        /// <remarks>
+        /// This operation fails if the key already exists in the map. To replace an existing entry, use the indexer.
+        /// </remarks>
+        /// <param name="key">The key to add</param>
+        /// <param name="value">The value to add.</param>
+        /// <exception cref="System.ArgumentException">The given key already exists in map.</exception>
+        public void Add(TKey key, TValue value)
+        {
+            // Validation of arguments happens in ContainsKey and the indexer
+            if (ContainsKey(key))
+            {
+                throw new ArgumentException("Key already exists in map", nameof(key));
+            }
+            this[key] = value;
+        }
+
+        /// <summary>
+        /// Determines whether the specified key is present in the map.
+        /// </summary>
+        /// <param name="key">The key to check.</param>
+        /// <returns><c>true</c> if the map contains the given key; <c>false</c> otherwise.</returns>
+        public bool ContainsKey(TKey key)
+        {
+            ProtoPreconditions.CheckNotNullUnconstrained(key, nameof(key));
+            return map.ContainsKey(key);
+        }
+
+        private bool ContainsValue(TValue value) =>
+            list.Any(pair => ValueEqualityComparer.Equals(pair.Value, value));
+
+        /// <summary>
+        /// Removes the entry identified by the given key from the map.
+        /// </summary>
+        /// <param name="key">The key indicating the entry to remove from the map.</param>
+        /// <returns><c>true</c> if the map contained the given key before the entry was removed; <c>false</c> otherwise.</returns>
+        public bool Remove(TKey key)
+        {
+            ProtoPreconditions.CheckNotNullUnconstrained(key, nameof(key));
+            if (map.TryGetValue(key, out LinkedListNode<KeyValuePair<TKey, TValue>> node))
+            {
+                map.Remove(key);
+                node.List.Remove(node);
+                return true;
+            }
+            else
+            {
+                return false;
+            }
+        }
+
+        /// <summary>
+        /// Gets the value associated with the specified key.
+        /// </summary>
+        /// <param name="key">The key whose value to get.</param>
+        /// <param name="value">When this method returns, the value associated with the specified key, if the key is found;
+        /// otherwise, the default value for the type of the <paramref name="value"/> parameter.
+        /// This parameter is passed uninitialized.</param>
+        /// <returns><c>true</c> if the map contains an element with the specified key; otherwise, <c>false</c>.</returns>
+        public bool TryGetValue(TKey key, out TValue value)
+        {
+            if (map.TryGetValue(key, out LinkedListNode<KeyValuePair<TKey, TValue>> node))
+            {
+                value = node.Value.Value;
+                return true;
+            }
+            else
+            {
+                value = default;
+                return false;
+            }
+        }
+
+        /// <summary>
+        /// Gets or sets the value associated with the specified key.
+        /// </summary>
+        /// <param name="key">The key of the value to get or set.</param>
+        /// <exception cref="KeyNotFoundException">The property is retrieved and key does not exist in the collection.</exception>
+        /// <returns>The value associated with the specified key. If the specified key is not found,
+        /// a get operation throws a <see cref="KeyNotFoundException"/>, and a set operation creates a new element with the specified key.</returns>
+        public TValue this[TKey key]
+        {
+            get
+            {
+                ProtoPreconditions.CheckNotNullUnconstrained(key, nameof(key));
+                if (TryGetValue(key, out TValue value))
+                {
+                    return value;
+                }
+                throw new KeyNotFoundException();
+            }
+            set
+            {
+                ProtoPreconditions.CheckNotNullUnconstrained(key, nameof(key));
+                // value == null check here is redundant, but avoids boxing.
+                if (value == null)
+                {
+                    ProtoPreconditions.CheckNotNullUnconstrained(value, nameof(value));
+                }
+                var pair = new KeyValuePair<TKey, TValue>(key, value);
+                if (map.TryGetValue(key, out LinkedListNode<KeyValuePair<TKey, TValue>> node))
+                {
+                    node.Value = pair;
+                }
+                else
+                {
+                    node = list.AddLast(pair);
+                    map[key] = node;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Gets a collection containing the keys in the map.
+        /// </summary>
+        public ICollection<TKey> Keys => new MapView<TKey>(this, pair => pair.Key, ContainsKey);
+
+        /// <summary>
+        /// Gets a collection containing the values in the map.
+        /// </summary>
+        public ICollection<TValue> Values => new MapView<TValue>(this, pair => pair.Value, ContainsValue);
+
+        /// <summary>
+        /// Adds the specified entries to the map. The keys and values are not automatically cloned.
+        /// </summary>
+        /// <param name="entries">The entries to add to the map.</param>
+        public void Add(IDictionary<TKey, TValue> entries)
+        {
+            ProtoPreconditions.CheckNotNull(entries, nameof(entries));
+            foreach (var pair in entries)
+            {
+                Add(pair.Key, pair.Value);
+            }
+        }
+
+        /// <summary>
+        /// Adds the specified entries to the map, replacing any existing entries with the same keys.
+        /// The keys and values are not automatically cloned.
+        /// </summary>
+        /// <remarks>This method primarily exists to be called from MergeFrom methods in generated classes for messages.</remarks>
+        /// <param name="entries">The entries to add to the map.</param>
+        public void MergeFrom(IDictionary<TKey, TValue> entries)
+        {
+            ProtoPreconditions.CheckNotNull(entries, nameof(entries));
+            foreach (var pair in entries)
+            {
+                this[pair.Key] = pair.Value;
+            }
+        }
+
+        /// <summary>
+        /// Returns an enumerator that iterates through the collection.
+        /// </summary>
+        /// <returns>
+        /// An enumerator that can be used to iterate through the collection.
+        /// </returns>
+        public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator() => list.GetEnumerator();
+
+        /// <summary>
+        /// Returns an enumerator that iterates through a collection.
+        /// </summary>
+        /// <returns>
+        /// An <see cref="T:System.Collections.IEnumerator" /> object that can be used to iterate through the collection.
+        /// </returns>
+        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+
+        /// <summary>
+        /// Adds the specified item to the map.
+        /// </summary>
+        /// <param name="item">The item to add to the map.</param>
+        void ICollection<KeyValuePair<TKey, TValue>>.Add(KeyValuePair<TKey, TValue> item) => Add(item.Key, item.Value);
+
+        /// <summary>
+        /// Removes all items from the map.
+        /// </summary>
+        public void Clear()
+        {
+            list.Clear();
+            map.Clear();
+        }
+
+        /// <summary>
+        /// Determines whether map contains an entry equivalent to the given key/value pair.
+        /// </summary>
+        /// <param name="item">The key/value pair to find.</param>
+        /// <returns></returns>
+        bool ICollection<KeyValuePair<TKey, TValue>>.Contains(KeyValuePair<TKey, TValue> item) =>
+            TryGetValue(item.Key, out TValue value) && ValueEqualityComparer.Equals(item.Value, value);
+
+        /// <summary>
+        /// Copies the key/value pairs in this map to an array.
+        /// </summary>
+        /// <param name="array">The array to copy the entries into.</param>
+        /// <param name="arrayIndex">The index of the array at which to start copying values.</param>
+        void ICollection<KeyValuePair<TKey, TValue>>.CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex) =>
+            list.CopyTo(array, arrayIndex);
+
+        /// <summary>
+        /// Removes the specified key/value pair from the map.
+        /// </summary>
+        /// <remarks>Both the key and the value must be found for the entry to be removed.</remarks>
+        /// <param name="item">The key/value pair to remove.</param>
+        /// <returns><c>true</c> if the key/value pair was found and removed; <c>false</c> otherwise.</returns>
+        bool ICollection<KeyValuePair<TKey, TValue>>.Remove(KeyValuePair<TKey, TValue> item)
+        {
+            if (item.Key == null)
+            {
+                throw new ArgumentException("Key is null", nameof(item));
+            }
+            if (map.TryGetValue(item.Key, out LinkedListNode<KeyValuePair<TKey, TValue>> node) &&
+                EqualityComparer<TValue>.Default.Equals(item.Value, node.Value.Value))
+            {
+                map.Remove(item.Key);
+                node.List.Remove(node);
+                return true;
+            }
+            else
+            {
+                return false;
+            }
+        }
+
+        /// <summary>
+        /// Gets the number of elements contained in the map.
+        /// </summary>
+        public int Count => list.Count;
+
+        /// <summary>
+        /// Gets a value indicating whether the map is read-only.
+        /// </summary>
+        public bool IsReadOnly => false;
+
+        /// <summary>
+        /// Determines whether the specified <see cref="System.Object" />, is equal to this instance.
+        /// </summary>
+        /// <param name="other">The <see cref="System.Object" /> to compare with this instance.</param>
+        /// <returns>
+        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
+        /// </returns>
+        public override bool Equals(object other) => Equals(other as MapField<TKey, TValue>);
+
+        /// <summary>
+        /// Returns a hash code for this instance.
+        /// </summary>
+        /// <returns>
+        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table. 
+        /// </returns>
+        public override int GetHashCode()
+        {
+            var keyComparer = KeyEqualityComparer;
+            var valueComparer = ValueEqualityComparer;
+            int hash = 0;
+            foreach (var pair in list)
+            {
+                hash ^= keyComparer.GetHashCode(pair.Key) * 31 + valueComparer.GetHashCode(pair.Value);
+            }
+            return hash;
+        }
+
+        /// <summary>
+        /// Compares this map with another for equality.
+        /// </summary>
+        /// <remarks>
+        /// The order of the key/value pairs in the maps is not deemed significant in this comparison.
+        /// </remarks>
+        /// <param name="other">The map to compare this with.</param>
+        /// <returns><c>true</c> if <paramref name="other"/> refers to an equal map; <c>false</c> otherwise.</returns>
+        public bool Equals(MapField<TKey, TValue> other)
+        {
+            if (other == null)
+            {
+                return false;
+            }
+            if (other == this)
+            {
+                return true;
+            }
+            if (other.Count != this.Count)
+            {
+                return false;
+            }
+            var valueComparer = ValueEqualityComparer;
+            foreach (var pair in this)
+            {
+                if (!other.TryGetValue(pair.Key, out TValue value))
+                {
+                    return false;
+                }
+                if (!valueComparer.Equals(value, pair.Value))
+                {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        /// <summary>
+        /// Adds entries to the map from the given stream.
+        /// </summary>
+        /// <remarks>
+        /// It is assumed that the stream is initially positioned after the tag specified by the codec.
+        /// This method will continue reading entries from the stream until the end is reached, or
+        /// a different tag is encountered.
+        /// </remarks>
+        /// <param name="input">Stream to read from</param>
+        /// <param name="codec">Codec describing how the key/value pairs are encoded</param>
+        public void AddEntriesFrom(CodedInputStream input, Codec codec)
+        {
+            ParseContext.Initialize(input, out ParseContext ctx);
+            try
+            {
+                AddEntriesFrom(ref ctx, codec);
+            }
+            finally
+            {
+                ctx.CopyStateTo(input);
+            }
+        }
+
+        /// <summary>
+        /// Adds entries to the map from the given parse context.
+        /// </summary>
+        /// <remarks>
+        /// It is assumed that the input is initially positioned after the tag specified by the codec.
+        /// This method will continue reading entries from the input until the end is reached, or
+        /// a different tag is encountered.
+        /// </remarks>
+        /// <param name="ctx">Input to read from</param>
+        /// <param name="codec">Codec describing how the key/value pairs are encoded</param>
+        [SecuritySafeCritical]
+        public void AddEntriesFrom(ref ParseContext ctx, Codec codec)
+        {
+            do
+            {
+                KeyValuePair<TKey, TValue> entry = ParsingPrimitivesMessages.ReadMapEntry(ref ctx, codec);
+                this[entry.Key] = entry.Value;
+            } while (ParsingPrimitives.MaybeConsumeTag(ref ctx.buffer, ref ctx.state, codec.MapTag));
+        }
+
+        /// <summary>
+        /// Writes the contents of this map to the given coded output stream, using the specified codec
+        /// to encode each entry.
+        /// </summary>
+        /// <param name="output">The output stream to write to.</param>
+        /// <param name="codec">The codec to use for each entry.</param>
+        public void WriteTo(CodedOutputStream output, Codec codec)
+        {
+            WriteContext.Initialize(output, out WriteContext ctx);
+            try
+            {
+                WriteTo(ref ctx, codec);
+            }
+            finally
+            {
+                ctx.CopyStateTo(output);
+            }
+        }
+
+        /// <summary>
+        /// Writes the contents of this map to the given write context, using the specified codec
+        /// to encode each entry.
+        /// </summary>
+        /// <param name="ctx">The write context to write to.</param>
+        /// <param name="codec">The codec to use for each entry.</param>
+        [SecuritySafeCritical]
+        public void WriteTo(ref WriteContext ctx, Codec codec)
+        {
+            foreach (var entry in list)
+            {
+                ctx.WriteTag(codec.MapTag);
+
+                WritingPrimitives.WriteLength(ref ctx.buffer, ref ctx.state, CalculateEntrySize(codec, entry));
+                codec.KeyCodec.WriteTagAndValue(ref ctx, entry.Key);
+                codec.ValueCodec.WriteTagAndValue(ref ctx, entry.Value);
+            }
+        }
+
+        /// <summary>
+        /// Calculates the size of this map based on the given entry codec.
+        /// </summary>
+        /// <param name="codec">The codec to use to encode each entry.</param>
+        /// <returns></returns>
+        public int CalculateSize(Codec codec)
+        {
+            if (Count == 0)
+            {
+                return 0;
+            }
+            int size = 0;
+            foreach (var entry in list)
+            {
+                int entrySize = CalculateEntrySize(codec, entry);
+
+                size += CodedOutputStream.ComputeRawVarint32Size(codec.MapTag);
+                size += CodedOutputStream.ComputeLengthSize(entrySize) + entrySize;
+            }
+            return size;
+        }
+
+        private static int CalculateEntrySize(Codec codec, KeyValuePair<TKey, TValue> entry)
+        {
+            return codec.KeyCodec.CalculateSizeWithTag(entry.Key) + codec.ValueCodec.CalculateSizeWithTag(entry.Value);
+        }
+
+        /// <summary>
+        /// Returns a string representation of this repeated field, in the same
+        /// way as it would be represented by the default JSON formatter.
+        /// </summary>
+        public override string ToString()
+        {
+            var writer = new StringWriter();
+            JsonFormatter.Default.WriteDictionary(writer, this);
+            return writer.ToString();
+        }
+
+        #region IDictionary explicit interface implementation
+
+        void IDictionary.Add(object key, object value) => Add((TKey)key, (TValue)value);
+
+        bool IDictionary.Contains(object key) => key is TKey k && ContainsKey(k);
+
+        IDictionaryEnumerator IDictionary.GetEnumerator() => new DictionaryEnumerator(GetEnumerator());
+
+        void IDictionary.Remove(object key)
+        {
+            ProtoPreconditions.CheckNotNull(key, nameof(key));
+            if (key is TKey k)
+            {
+                Remove(k);
+            }
+        }
+
+        void ICollection.CopyTo(Array array, int index)
+        {
+            // This is ugly and slow as heck, but with any luck it will never be used anyway.
+            ICollection temp = this.Select(pair => new DictionaryEntry(pair.Key, pair.Value)).ToList();
+            temp.CopyTo(array, index);
+        }
+
+        bool IDictionary.IsFixedSize => false;
+
+        ICollection IDictionary.Keys => (ICollection)Keys;
+
+        ICollection IDictionary.Values => (ICollection)Values;
+
+        bool ICollection.IsSynchronized => false;
+
+        object ICollection.SyncRoot => this;
+
+        object IDictionary.this[object key]
+        {
+            get
+            {
+                ProtoPreconditions.CheckNotNull(key, nameof(key));
+                if (key is TKey k)
+                {
+                    TryGetValue(k, out TValue value);
+                    return value;
+                }
+                return null;
+            }
+
+            set
+            {
+                this[(TKey)key] = (TValue)value;
+            }
+        }
+        #endregion
+
+        #region IReadOnlyDictionary explicit interface implementation
+        IEnumerable<TKey> IReadOnlyDictionary<TKey, TValue>.Keys => Keys;
+        IEnumerable<TValue> IReadOnlyDictionary<TKey, TValue>.Values => Values;
+        #endregion
+
+        private class DictionaryEnumerator : IDictionaryEnumerator
+        {
+            private readonly IEnumerator<KeyValuePair<TKey, TValue>> enumerator;
+
+            internal DictionaryEnumerator(IEnumerator<KeyValuePair<TKey, TValue>> enumerator)
+            {
+                this.enumerator = enumerator;
+            }
+
+            public bool MoveNext() => enumerator.MoveNext();
+
+            public void Reset() => enumerator.Reset();
+
+            public object Current => Entry;
+            public DictionaryEntry Entry => new DictionaryEntry(Key, Value);
+            public object Key => enumerator.Current.Key;
+            public object Value => enumerator.Current.Value;
+        }
+
+        /// <summary>
+        /// A codec for a specific map field. This contains all the information required to encode and
+        /// decode the nested messages.
+        /// </summary>
+        public sealed class Codec
+        {
+            private readonly FieldCodec<TKey> keyCodec;
+            private readonly FieldCodec<TValue> valueCodec;
+            private readonly uint mapTag;
+
+            /// <summary>
+            /// Creates a new entry codec based on a separate key codec and value codec,
+            /// and the tag to use for each map entry.
+            /// </summary>
+            /// <param name="keyCodec">The key codec.</param>
+            /// <param name="valueCodec">The value codec.</param>
+            /// <param name="mapTag">The map tag to use to introduce each map entry.</param>
+            public Codec(FieldCodec<TKey> keyCodec, FieldCodec<TValue> valueCodec, uint mapTag)
+            {
+                this.keyCodec = keyCodec;
+                this.valueCodec = valueCodec;
+                this.mapTag = mapTag;
+            }
+
+            /// <summary>
+            /// The key codec.
+            /// </summary>
+            internal FieldCodec<TKey> KeyCodec => keyCodec;
+
+            /// <summary>
+            /// The value codec.
+            /// </summary>
+            internal FieldCodec<TValue> ValueCodec => valueCodec;
+
+            /// <summary>
+            /// The tag used in the enclosing message to indicate map entries.
+            /// </summary>
+            internal uint MapTag => mapTag;
+        }
+
+        private class MapView<T> : ICollection<T>, ICollection
+        {
+            private readonly MapField<TKey, TValue> parent;
+            private readonly Func<KeyValuePair<TKey, TValue>, T> projection;
+            private readonly Func<T, bool> containsCheck;
+
+            internal MapView(
+                MapField<TKey, TValue> parent,
+                Func<KeyValuePair<TKey, TValue>, T> projection,
+                Func<T, bool> containsCheck)
+            {
+                this.parent = parent;
+                this.projection = projection;
+                this.containsCheck = containsCheck;
+            }
+
+            public int Count => parent.Count; 
+
+            public bool IsReadOnly => true;
+
+            public bool IsSynchronized => false;
+
+            public object SyncRoot => parent;
+
+            public void Add(T item) => throw new NotSupportedException();
+
+            public void Clear() => throw new NotSupportedException();
+
+            public bool Contains(T item) => containsCheck(item);
+
+            public void CopyTo(T[] array, int arrayIndex)
+            {
+                if (arrayIndex < 0)
+                {
+                    throw new ArgumentOutOfRangeException(nameof(arrayIndex));
+                }
+                if (arrayIndex + Count > array.Length)
+                {
+                    throw new ArgumentException("Not enough space in the array", nameof(array));
+                }
+                foreach (var item in this)
+                {
+                    array[arrayIndex++] = item;
+                }
+            }
+
+            public IEnumerator<T> GetEnumerator()
+            {
+                return parent.list.Select(projection).GetEnumerator();
+            }
+
+            public bool Remove(T item) => throw new NotSupportedException();
+
+            IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+
+            public void CopyTo(Array array, int index)
+            {
+                if (index < 0)
+                {
+                    throw new ArgumentOutOfRangeException(nameof(index));
+                }
+                if (index + Count > array.Length)
+                {
+                    throw new ArgumentException("Not enough space in the array", nameof(array));
+                }
+                foreach (var item in this)
+                {
+                    array.SetValue(item, index++);
+                }
+            }
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf/Collections/ProtobufEqualityComparers.cs

@@ -0,0 +1,130 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2017 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.Collections.Generic;
+
+namespace Google.Protobuf.Collections
+{
+    /// <summary>
+    /// Provides a central place to implement equality comparisons, primarily for bitwise float/double equality.
+    /// </summary>
+    public static class ProtobufEqualityComparers
+    {
+        /// <summary>
+        /// Returns an equality comparer for <typeparamref name="T"/> suitable for Protobuf equality comparisons.
+        /// This is usually just the default equality comparer for the type, but floating point numbers are compared
+        /// bitwise.
+        /// </summary>
+        /// <typeparam name="T">The type of equality comparer to return.</typeparam>
+        /// <returns>The equality comparer.</returns>
+        public static EqualityComparer<T> GetEqualityComparer<T>()
+        {
+            return typeof(T) == typeof(double) ? (EqualityComparer<T>) (object) BitwiseDoubleEqualityComparer
+                : typeof(T) == typeof(float) ? (EqualityComparer<T>) (object) BitwiseSingleEqualityComparer
+                : typeof(T) == typeof(double?) ? (EqualityComparer<T>) (object) BitwiseNullableDoubleEqualityComparer
+                : typeof(T) == typeof(float?) ? (EqualityComparer<T>) (object) BitwiseNullableSingleEqualityComparer
+                : EqualityComparer<T>.Default;
+        }
+
+        /// <summary>
+        /// Returns an equality comparer suitable for comparing 64-bit floating point values, by bitwise comparison.
+        /// (NaN values are considered equal, but only when they have the same representation.)
+        /// </summary>
+        public static EqualityComparer<double> BitwiseDoubleEqualityComparer { get; } = new BitwiseDoubleEqualityComparerImpl();
+
+        /// <summary>
+        /// Returns an equality comparer suitable for comparing 32-bit floating point values, by bitwise comparison.
+        /// (NaN values are considered equal, but only when they have the same representation.)
+        /// </summary>
+        public static EqualityComparer<float> BitwiseSingleEqualityComparer { get; } = new BitwiseSingleEqualityComparerImpl();
+
+        /// <summary>
+        /// Returns an equality comparer suitable for comparing nullable 64-bit floating point values, by bitwise comparison.
+        /// (NaN values are considered equal, but only when they have the same representation.)
+        /// </summary>
+        public static EqualityComparer<double?> BitwiseNullableDoubleEqualityComparer { get; } = new BitwiseNullableDoubleEqualityComparerImpl();
+
+        /// <summary>
+        /// Returns an equality comparer suitable for comparing nullable 32-bit floating point values, by bitwise comparison.
+        /// (NaN values are considered equal, but only when they have the same representation.)
+        /// </summary>
+        public static EqualityComparer<float?> BitwiseNullableSingleEqualityComparer { get; } = new BitwiseNullableSingleEqualityComparerImpl();
+
+        private class BitwiseDoubleEqualityComparerImpl : EqualityComparer<double>
+        {
+            public override bool Equals(double x, double y) =>
+                BitConverter.DoubleToInt64Bits(x) == BitConverter.DoubleToInt64Bits(y);
+
+            public override int GetHashCode(double obj) =>
+                BitConverter.DoubleToInt64Bits(obj).GetHashCode();
+        }
+
+        private class BitwiseSingleEqualityComparerImpl : EqualityComparer<float>
+        {
+            // Just promote values to double and use BitConverter.DoubleToInt64Bits,
+            // as there's no BitConverter.SingleToInt32Bits, unfortunately.
+
+            public override bool Equals(float x, float y) =>
+                BitConverter.DoubleToInt64Bits(x) == BitConverter.DoubleToInt64Bits(y);
+
+            public override int GetHashCode(float obj) =>
+                BitConverter.DoubleToInt64Bits(obj).GetHashCode();
+        }
+
+        private class BitwiseNullableDoubleEqualityComparerImpl : EqualityComparer<double?>
+        {
+            public override bool Equals(double? x, double? y) =>
+                x == null && y == null ? true
+                : x == null || y == null ? false
+                : BitwiseDoubleEqualityComparer.Equals(x.Value, y.Value);
+
+            // The hash code for null is just a constant which is at least *unlikely* to be used
+            // elsewhere. (Compared with 0, say.)
+            public override int GetHashCode(double? obj) =>
+                obj == null ? 293864 : BitwiseDoubleEqualityComparer.GetHashCode(obj.Value);
+        }
+
+        private class BitwiseNullableSingleEqualityComparerImpl : EqualityComparer<float?>
+        {
+            public override bool Equals(float? x, float? y) =>
+                x == null && y == null ? true
+                : x == null || y == null ? false
+                : BitwiseSingleEqualityComparer.Equals(x.Value, y.Value);
+
+            // The hash code for null is just a constant which is at least *unlikely* to be used
+            // elsewhere. (Compared with 0, say.)
+            public override int GetHashCode(float? obj) =>
+                obj == null ? 293864 : BitwiseSingleEqualityComparer.GetHashCode(obj.Value);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf/Collections/RepeatedField.cs

@@ -0,0 +1,669 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.IO;
+using System.Security;
+
+namespace Google.Protobuf.Collections
+{
+    /// <summary>
+    /// The contents of a repeated field: essentially, a collection with some extra
+    /// restrictions (no null values) and capabilities (deep cloning).
+    /// </summary>
+    /// <remarks>
+    /// This implementation does not generally prohibit the use of types which are not
+    /// supported by Protocol Buffers but nor does it guarantee that all operations will work in such cases.
+    /// </remarks>
+    /// <typeparam name="T">The element type of the repeated field.</typeparam>
+    public sealed class RepeatedField<T> : IList<T>, IList, IDeepCloneable<RepeatedField<T>>, IEquatable<RepeatedField<T>>, IReadOnlyList<T>
+    {
+        private static readonly EqualityComparer<T> EqualityComparer = ProtobufEqualityComparers.GetEqualityComparer<T>();
+        private static readonly T[] EmptyArray = new T[0];
+        private const int MinArraySize = 8;
+
+        private T[] array = EmptyArray;
+        private int count = 0;
+
+        /// <summary>
+        /// Creates a deep clone of this repeated field.
+        /// </summary>
+        /// <remarks>
+        /// If the field type is
+        /// a message type, each element is also cloned; otherwise, it is
+        /// assumed that the field type is primitive (including string and
+        /// bytes, both of which are immutable) and so a simple copy is
+        /// equivalent to a deep clone.
+        /// </remarks>
+        /// <returns>A deep clone of this repeated field.</returns>
+        public RepeatedField<T> Clone()
+        {
+            RepeatedField<T> clone = new RepeatedField<T>();
+            if (array != EmptyArray)
+            {
+                clone.array = (T[])array.Clone();
+                if (clone.array is IDeepCloneable<T>[] cloneableArray)
+                {
+                    for (int i = 0; i < count; i++)
+                    {
+                        clone.array[i] = cloneableArray[i].Clone();
+                    }
+                }
+            }
+            clone.count = count;
+            return clone;
+        }
+
+        /// <summary>
+        /// Adds the entries from the given input stream, decoding them with the specified codec.
+        /// </summary>
+        /// <param name="input">The input stream to read from.</param>
+        /// <param name="codec">The codec to use in order to read each entry.</param>
+        public void AddEntriesFrom(CodedInputStream input, FieldCodec<T> codec)
+        {
+            ParseContext.Initialize(input, out ParseContext ctx);
+            try
+            {
+                AddEntriesFrom(ref ctx, codec);
+            }
+            finally
+            {
+                ctx.CopyStateTo(input);
+            }
+        }
+
+        /// <summary>
+        /// Adds the entries from the given parse context, decoding them with the specified codec.
+        /// </summary>
+        /// <param name="ctx">The input to read from.</param>
+        /// <param name="codec">The codec to use in order to read each entry.</param>
+        [SecuritySafeCritical]
+        public void AddEntriesFrom(ref ParseContext ctx, FieldCodec<T> codec)
+        {
+            // TODO: Inline some of the Add code, so we can avoid checking the size on every
+            // iteration.
+            uint tag = ctx.state.lastTag;
+            var reader = codec.ValueReader;
+            // Non-nullable value types can be packed or not.
+            if (FieldCodec<T>.IsPackedRepeatedField(tag))
+            {
+                int length = ctx.ReadLength();
+                if (length > 0)
+                {
+                    int oldLimit = SegmentedBufferHelper.PushLimit(ref ctx.state, length);
+
+                    // If the content is fixed size then we can calculate the length
+                    // of the repeated field and pre-initialize the underlying collection.
+                    //
+                    // Check that the supplied length doesn't exceed the underlying buffer.
+                    // That prevents a malicious length from initializing a very large collection.
+                    if (codec.FixedSize > 0 && length % codec.FixedSize == 0 && ParsingPrimitives.IsDataAvailable(ref ctx.state, length))
+                    {
+                        EnsureSize(count + (length / codec.FixedSize));
+
+                        while (!SegmentedBufferHelper.IsReachedLimit(ref ctx.state))
+                        {
+                            // Only FieldCodecs with a fixed size can reach here, and they are all known
+                            // types that don't allow the user to specify a custom reader action.
+                            // reader action will never return null.
+                            array[count++] = reader(ref ctx);
+                        }
+                    }
+                    else
+                    {
+                        // Content is variable size so add until we reach the limit.
+                        while (!SegmentedBufferHelper.IsReachedLimit(ref ctx.state))
+                        {
+                            Add(reader(ref ctx));
+                        }
+                    }
+                    SegmentedBufferHelper.PopLimit(ref ctx.state, oldLimit);
+                }
+                // Empty packed field. Odd, but valid - just ignore.
+            }
+            else
+            {
+                // Not packed... (possibly not packable)
+                do
+                {
+                    Add(reader(ref ctx));
+                } while (ParsingPrimitives.MaybeConsumeTag(ref ctx.buffer, ref ctx.state, tag));
+            }
+        }
+
+        /// <summary>
+        /// Calculates the size of this collection based on the given codec.
+        /// </summary>
+        /// <param name="codec">The codec to use when encoding each field.</param>
+        /// <returns>The number of bytes that would be written to an output by one of the <c>WriteTo</c> methods,
+        /// using the same codec.</returns>
+        public int CalculateSize(FieldCodec<T> codec)
+        {
+            if (count == 0)
+            {
+                return 0;
+            }
+            uint tag = codec.Tag;
+            if (codec.PackedRepeatedField)
+            {
+                int dataSize = CalculatePackedDataSize(codec);
+                return CodedOutputStream.ComputeRawVarint32Size(tag) +
+                    CodedOutputStream.ComputeLengthSize(dataSize) +
+                    dataSize;
+            }
+            else
+            {
+                var sizeCalculator = codec.ValueSizeCalculator;
+                int size = count * CodedOutputStream.ComputeRawVarint32Size(tag);
+                if (codec.EndTag != 0)
+                {
+                    size += count * CodedOutputStream.ComputeRawVarint32Size(codec.EndTag);
+                }
+                for (int i = 0; i < count; i++)
+                {
+                    size += sizeCalculator(array[i]);
+                }
+                return size;
+            }
+        }
+
+        private int CalculatePackedDataSize(FieldCodec<T> codec)
+        {
+            int fixedSize = codec.FixedSize;
+            if (fixedSize == 0)
+            {
+                var calculator = codec.ValueSizeCalculator;
+                int tmp = 0;
+                for (int i = 0; i < count; i++)
+                {
+                    tmp += calculator(array[i]);
+                }
+                return tmp;
+            }
+            else
+            {
+                return fixedSize * Count;
+            }
+        }
+
+        /// <summary>
+        /// Writes the contents of this collection to the given <see cref="CodedOutputStream"/>,
+        /// encoding each value using the specified codec.
+        /// </summary>
+        /// <param name="output">The output stream to write to.</param>
+        /// <param name="codec">The codec to use when encoding each value.</param>
+        public void WriteTo(CodedOutputStream output, FieldCodec<T> codec)
+        {
+            WriteContext.Initialize(output, out WriteContext ctx);
+            try
+            {
+                WriteTo(ref ctx, codec);
+            }
+            finally
+            {
+                ctx.CopyStateTo(output);
+            }
+        }
+
+        /// <summary>
+        /// Writes the contents of this collection to the given write context,
+        /// encoding each value using the specified codec.
+        /// </summary>
+        /// <param name="ctx">The write context to write to.</param>
+        /// <param name="codec">The codec to use when encoding each value.</param>
+        [SecuritySafeCritical]
+        public void WriteTo(ref WriteContext ctx, FieldCodec<T> codec)
+        {
+            if (count == 0)
+            {
+                return;
+            }
+            var writer = codec.ValueWriter;
+            var tag = codec.Tag;
+            if (codec.PackedRepeatedField)
+            {
+                // Packed primitive type
+                int size = CalculatePackedDataSize(codec);
+                ctx.WriteTag(tag);
+                ctx.WriteLength(size);
+                for (int i = 0; i < count; i++)
+                {
+                    writer(ref ctx, array[i]);
+                }
+            }
+            else
+            {
+                // Not packed: a simple tag/value pair for each value.
+                // Can't use codec.WriteTagAndValue, as that omits default values.
+                for (int i = 0; i < count; i++)
+                {
+                    ctx.WriteTag(tag);
+                    writer(ref ctx, array[i]);
+                    if (codec.EndTag != 0)
+                    {
+                        ctx.WriteTag(codec.EndTag);
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// Gets and sets the capacity of the RepeatedField's internal array.
+        /// When set, the internal array is reallocated to the given capacity.
+        /// <exception cref="ArgumentOutOfRangeException">The new value is less than <see cref="Count"/>.</exception>
+        /// </summary>
+        public int Capacity
+        {
+            get { return array.Length; }
+            set
+            {
+                if (value < count)
+                {
+                    throw new ArgumentOutOfRangeException("Capacity", value,
+                        $"Cannot set Capacity to a value smaller than the current item count, {count}");
+                }
+
+                if (value >= 0 && value != array.Length)
+                {
+                    SetSize(value);
+                }
+            }
+        }
+
+        // May increase the size of the internal array, but will never shrink it.
+        private void EnsureSize(int size)
+        {
+            if (array.Length < size)
+            {
+                size = Math.Max(size, MinArraySize);
+                int newSize = Math.Max(array.Length * 2, size);
+                SetSize(newSize);
+            }
+        }
+
+        // Sets the internal array to an exact size.
+        private void SetSize(int size)
+        {
+            if (size != array.Length)
+            {
+                var tmp = new T[size];
+                Array.Copy(array, 0, tmp, 0, count);
+                array = tmp;
+            }
+        }
+
+        /// <summary>
+        /// Adds the specified item to the collection.
+        /// </summary>
+        /// <param name="item">The item to add.</param>
+        public void Add(T item)
+        {
+            ProtoPreconditions.CheckNotNullUnconstrained(item, nameof(item));
+            EnsureSize(count + 1);
+            array[count++] = item;
+        }
+
+        /// <summary>
+        /// Removes all items from the collection.
+        /// </summary>
+        public void Clear()
+        {
+            // Clear the content of the array (so that any objects it referred to can be garbage collected)
+            // but keep the capacity the same. This allows large repeated fields to be reused without
+            // array reallocation.
+            Array.Clear(array, 0, count);
+            count = 0;
+        }
+
+        /// <summary>
+        /// Determines whether this collection contains the given item.
+        /// </summary>
+        /// <param name="item">The item to find.</param>
+        /// <returns><c>true</c> if this collection contains the given item; <c>false</c> otherwise.</returns>
+        public bool Contains(T item) => IndexOf(item) != -1;
+
+        /// <summary>
+        /// Copies this collection to the given array.
+        /// </summary>
+        /// <param name="array">The array to copy to.</param>
+        /// <param name="arrayIndex">The first index of the array to copy to.</param>
+        public void CopyTo(T[] array, int arrayIndex)
+        {
+            Array.Copy(this.array, 0, array, arrayIndex, count);
+        }
+
+        /// <summary>
+        /// Removes the specified item from the collection
+        /// </summary>
+        /// <param name="item">The item to remove.</param>
+        /// <returns><c>true</c> if the item was found and removed; <c>false</c> otherwise.</returns>
+        public bool Remove(T item)
+        {
+            int index = IndexOf(item);
+            if (index == -1)
+            {
+                return false;
+            }            
+            Array.Copy(array, index + 1, array, index, count - index - 1);
+            count--;
+            array[count] = default;
+            return true;
+        }
+
+        /// <summary>
+        /// Gets the number of elements contained in the collection.
+        /// </summary>
+        public int Count => count;
+
+        /// <summary>
+        /// Gets a value indicating whether the collection is read-only.
+        /// </summary>
+        public bool IsReadOnly => false;
+
+        /// <summary>
+        /// Adds all of the specified values into this collection.
+        /// </summary>
+        /// <param name="values">The values to add to this collection.</param>
+        public void AddRange(IEnumerable<T> values)
+        {
+            ProtoPreconditions.CheckNotNull(values, nameof(values));
+
+            // Optimization 1: If the collection we're adding is already a RepeatedField<T>,
+            // we know the values are valid.
+            if (values is RepeatedField<T> otherRepeatedField)
+            {
+                EnsureSize(count + otherRepeatedField.count);
+                Array.Copy(otherRepeatedField.array, 0, array, count, otherRepeatedField.count);
+                count += otherRepeatedField.count;
+                return;
+            }
+
+            // Optimization 2: The collection is an ICollection, so we can expand
+            // just once and ask the collection to copy itself into the array.
+            if (values is ICollection collection)
+            {
+                var extraCount = collection.Count;
+                // For reference types and nullable value types, we need to check that there are no nulls
+                // present. (This isn't a thread-safe approach, but we don't advertise this is thread-safe.)
+                // We expect the JITter to optimize this test to true/false, so it's effectively conditional
+                // specialization.
+                if (default(T) == null)
+                {
+                    // TODO: Measure whether iterating once to check and then letting the collection copy
+                    // itself is faster or slower than iterating and adding as we go. For large
+                    // collections this will not be great in terms of cache usage... but the optimized
+                    // copy may be significantly faster than doing it one at a time.
+                    foreach (var item in collection)
+                    {
+                        if (item == null)
+                        {
+                            throw new ArgumentException("Sequence contained null element", nameof(values));
+                        }
+                    }
+                }
+                EnsureSize(count + extraCount);
+                collection.CopyTo(array, count);
+                count += extraCount;
+                return;
+            }
+
+            // We *could* check for ICollection<T> as well, but very very few collections implement
+            // ICollection<T> but not ICollection. (HashSet<T> does, for one...)
+
+            // Fall back to a slower path of adding items one at a time.
+            foreach (T item in values)
+            {
+                Add(item);
+            }
+        }
+
+        /// <summary>
+        /// Adds all of the specified values into this collection. This method is present to
+        /// allow repeated fields to be constructed from queries within collection initializers.
+        /// Within non-collection-initializer code, consider using the equivalent <see cref="AddRange"/>
+        /// method instead for clarity.
+        /// </summary>
+        /// <param name="values">The values to add to this collection.</param>
+        public void Add(IEnumerable<T> values)
+        {
+            AddRange(values);
+        }
+
+        /// <summary>
+        /// Returns an enumerator that iterates through the collection.
+        /// </summary>
+        /// <returns>
+        /// An enumerator that can be used to iterate through the collection.
+        /// </returns>
+        public IEnumerator<T> GetEnumerator()
+        {
+            for (int i = 0; i < count; i++)
+            {
+                yield return array[i];
+            }
+        }
+
+        /// <summary>
+        /// Determines whether the specified <see cref="System.Object" />, is equal to this instance.
+        /// </summary>
+        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
+        /// <returns>
+        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
+        /// </returns>
+        public override bool Equals(object obj) => Equals(obj as RepeatedField<T>);
+        
+        /// <summary>
+        /// Returns an enumerator that iterates through a collection.
+        /// </summary>
+        /// <returns>
+        /// An <see cref="T:System.Collections.IEnumerator" /> object that can be used to iterate through the collection.
+        /// </returns>
+        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+
+        /// <summary>
+        /// Returns a hash code for this instance.
+        /// </summary>
+        /// <returns>
+        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table. 
+        /// </returns>
+        public override int GetHashCode()
+        {
+            int hash = 0;
+            for (int i = 0; i < count; i++)
+            {
+                hash = hash * 31 + array[i].GetHashCode();
+            }
+            return hash;
+        }
+
+        /// <summary>
+        /// Compares this repeated field with another for equality.
+        /// </summary>
+        /// <param name="other">The repeated field to compare this with.</param>
+        /// <returns><c>true</c> if <paramref name="other"/> refers to an equal repeated field; <c>false</c> otherwise.</returns>
+        public bool Equals(RepeatedField<T> other)
+        {
+            if (other is null)
+            {
+                return false;
+            }
+            if (ReferenceEquals(other, this))
+            {
+                return true;
+            }
+            if (other.Count != this.Count)
+            {
+                return false;
+            }
+            EqualityComparer<T> comparer = EqualityComparer;
+            for (int i = 0; i < count; i++)
+            {
+                if (!comparer.Equals(array[i], other.array[i]))
+                {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        /// <summary>
+        /// Returns the index of the given item within the collection, or -1 if the item is not
+        /// present.
+        /// </summary>
+        /// <param name="item">The item to find in the collection.</param>
+        /// <returns>The zero-based index of the item, or -1 if it is not found.</returns>
+        public int IndexOf(T item)
+        {
+            ProtoPreconditions.CheckNotNullUnconstrained(item, nameof(item));
+            EqualityComparer<T> comparer = EqualityComparer;
+            for (int i = 0; i < count; i++)
+            {
+                if (comparer.Equals(array[i], item))
+                {
+                    return i;
+                }
+            }
+            return -1;
+        }
+
+        /// <summary>
+        /// Inserts the given item at the specified index.
+        /// </summary>
+        /// <param name="index">The index at which to insert the item.</param>
+        /// <param name="item">The item to insert.</param>
+        public void Insert(int index, T item)
+        {
+            ProtoPreconditions.CheckNotNullUnconstrained(item, nameof(item));
+            if (index < 0 || index > count)
+            {
+                throw new ArgumentOutOfRangeException(nameof(index));
+            }
+            EnsureSize(count + 1);
+            Array.Copy(array, index, array, index + 1, count - index);
+            array[index] = item;
+            count++;
+        }
+
+        /// <summary>
+        /// Removes the item at the given index.
+        /// </summary>
+        /// <param name="index">The zero-based index of the item to remove.</param>
+        public void RemoveAt(int index)
+        {
+            if (index < 0 || index >= count)
+            {
+                throw new ArgumentOutOfRangeException(nameof(index));
+            }
+            Array.Copy(array, index + 1, array, index, count - index - 1);
+            count--;
+            array[count] = default;
+        }
+
+        /// <summary>
+        /// Returns a string representation of this repeated field, in the same
+        /// way as it would be represented by the default JSON formatter.
+        /// </summary>
+        public override string ToString()
+        {
+            var writer = new StringWriter();
+            JsonFormatter.Default.WriteList(writer, this);
+            return writer.ToString();
+        }
+
+        /// <summary>
+        /// Gets or sets the item at the specified index.
+        /// </summary>
+        /// <value>
+        /// The element at the specified index.
+        /// </value>
+        /// <param name="index">The zero-based index of the element to get or set.</param>
+        /// <returns>The item at the specified index.</returns>
+        public T this[int index]
+        {
+            get
+            {
+                if (index < 0 || index >= count)
+                {
+                    throw new ArgumentOutOfRangeException(nameof(index));
+                }
+                return array[index];
+            }
+            set
+            {
+                if (index < 0 || index >= count)
+                {
+                    throw new ArgumentOutOfRangeException(nameof(index));
+                }
+                ProtoPreconditions.CheckNotNullUnconstrained(value, nameof(value));
+                array[index] = value;
+            }
+        }
+
+        #region Explicit interface implementation for IList and ICollection.
+        bool IList.IsFixedSize => false;
+
+        void ICollection.CopyTo(Array array, int index) => Array.Copy(this.array, 0, array, index, count);
+
+        bool ICollection.IsSynchronized => false;
+
+        object ICollection.SyncRoot => this;
+
+        object IList.this[int index]
+        {
+            get => this[index];
+            set => this[index] = (T)value;
+        }
+
+        int IList.Add(object value)
+        {
+            Add((T) value);
+            return count - 1;
+        }
+
+        bool IList.Contains(object value) => (value is T t && Contains(t));
+
+        int IList.IndexOf(object value) => (value is T t) ? IndexOf(t) : -1;
+
+        void IList.Insert(int index, object value) => Insert(index, (T) value);
+
+        void IList.Remove(object value)
+        {
+            if (value is T t)
+            {
+                Remove(t);
+            }
+        }
+        #endregion        
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf/Compatibility/DynamicallyAccessedMemberTypes.cs

@@ -0,0 +1,127 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+#if !NET5_0_OR_GREATER
+// Copied with permission from https://github.com/dotnet/runtime/tree/8fbf206d0e518b45ca855832e8bfb391afa85972/src/libraries/System.Private.CoreLib/src/System/Diagnostics/CodeAnalysis
+namespace System.Diagnostics.CodeAnalysis
+{
+    /// <summary>
+    /// Specifies the types of members that are dynamically accessed.
+    ///
+    /// This enumeration has a <see cref="FlagsAttribute"/> attribute that allows a
+    /// bitwise combination of its member values.
+    /// </summary>
+    [Flags]
+    internal enum DynamicallyAccessedMemberTypes
+    {
+        /// <summary>
+        /// Specifies no members.
+        /// </summary>
+        None = 0,
+
+        /// <summary>
+        /// Specifies the default, parameterless public constructor.
+        /// </summary>
+        PublicParameterlessConstructor = 0x0001,
+
+        /// <summary>
+        /// Specifies all public constructors.
+        /// </summary>
+        PublicConstructors = 0x0002 | PublicParameterlessConstructor,
+
+        /// <summary>
+        /// Specifies all non-public constructors.
+        /// </summary>
+        NonPublicConstructors = 0x0004,
+
+        /// <summary>
+        /// Specifies all public methods.
+        /// </summary>
+        PublicMethods = 0x0008,
+
+        /// <summary>
+        /// Specifies all non-public methods.
+        /// </summary>
+        NonPublicMethods = 0x0010,
+
+        /// <summary>
+        /// Specifies all public fields.
+        /// </summary>
+        PublicFields = 0x0020,
+
+        /// <summary>
+        /// Specifies all non-public fields.
+        /// </summary>
+        NonPublicFields = 0x0040,
+
+        /// <summary>
+        /// Specifies all public nested types.
+        /// </summary>
+        PublicNestedTypes = 0x0080,
+
+        /// <summary>
+        /// Specifies all non-public nested types.
+        /// </summary>
+        NonPublicNestedTypes = 0x0100,
+
+        /// <summary>
+        /// Specifies all public properties.
+        /// </summary>
+        PublicProperties = 0x0200,
+
+        /// <summary>
+        /// Specifies all non-public properties.
+        /// </summary>
+        NonPublicProperties = 0x0400,
+
+        /// <summary>
+        /// Specifies all public events.
+        /// </summary>
+        PublicEvents = 0x0800,
+
+        /// <summary>
+        /// Specifies all non-public events.
+        /// </summary>
+        NonPublicEvents = 0x1000,
+
+        /// <summary>
+        /// Specifies all interfaces implemented by the type.
+        /// </summary>
+        Interfaces = 0x2000,
+
+        /// <summary>
+        /// Specifies all members.
+        /// </summary>
+        All = ~None
+    }
+}
+#endif

libs/protobuf/csharp/src/Google.Protobuf/Compatibility/DynamicallyAccessedMembersAttribute.cs

@@ -0,0 +1,83 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+#if !NET5_0_OR_GREATER
+// Copied with permission from https://github.com/dotnet/runtime/tree/8fbf206d0e518b45ca855832e8bfb391afa85972/src/libraries/System.Private.CoreLib/src/System/Diagnostics/CodeAnalysis
+namespace System.Diagnostics.CodeAnalysis
+{
+    /// <summary>
+    /// Indicates that certain members on a specified <see cref="Type"/> are accessed dynamically,
+    /// for example through <see cref="System.Reflection"/>.
+    /// </summary>
+    /// <remarks>
+    /// This allows tools to understand which members are being accessed during the execution
+    /// of a program.
+    ///
+    /// This attribute is valid on members whose type is <see cref="Type"/> or <see cref="string"/>.
+    ///
+    /// When this attribute is applied to a location of type <see cref="string"/>, the assumption is
+    /// that the string represents a fully qualified type name.
+    ///
+    /// When this attribute is applied to a class, interface, or struct, the members specified
+    /// can be accessed dynamically on <see cref="Type"/> instances returned from calling
+    /// <see cref="object.GetType"/> on instances of that class, interface, or struct.
+    ///
+    /// If the attribute is applied to a method it's treated as a special case and it implies
+    /// the attribute should be applied to the "this" parameter of the method. As such the attribute
+    /// should only be used on instance methods of types assignable to System.Type (or string, but no methods
+    /// will use it there).
+    /// </remarks>
+    [AttributeUsage(
+        AttributeTargets.Field | AttributeTargets.ReturnValue | AttributeTargets.GenericParameter |
+        AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.Method |
+        AttributeTargets.Class | AttributeTargets.Interface | AttributeTargets.Struct,
+        Inherited = false)]
+    internal sealed class DynamicallyAccessedMembersAttribute : Attribute
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DynamicallyAccessedMembersAttribute"/> class
+        /// with the specified member types.
+        /// </summary>
+        /// <param name="memberTypes">The types of members dynamically accessed.</param>
+        public DynamicallyAccessedMembersAttribute(DynamicallyAccessedMemberTypes memberTypes)
+        {
+            MemberTypes = memberTypes;
+        }
+
+        /// <summary>
+        /// Gets the <see cref="DynamicallyAccessedMemberTypes"/> which specifies the type
+        /// of members dynamically accessed.
+        /// </summary>
+        public DynamicallyAccessedMemberTypes MemberTypes { get; }
+    }
+}
+#endif

libs/protobuf/csharp/src/Google.Protobuf/Compatibility/PropertyInfoExtensions.cs

@@ -0,0 +1,64 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System.Reflection;
+
+namespace Google.Protobuf.Compatibility
+{
+    /// <summary>
+    /// Extension methods for <see cref="PropertyInfo"/>, effectively providing
+    /// the familiar members from previous desktop framework versions while
+    /// targeting the newer releases, .NET Core etc.
+    /// </summary>
+    internal static class PropertyInfoExtensions
+    {
+        /// <summary>
+        /// Returns the public getter of a property, or null if there is no such getter
+        /// (either because it's read-only, or the getter isn't public).
+        /// </summary>
+        internal static MethodInfo GetGetMethod(this PropertyInfo target)
+        {
+            var method = target.GetMethod;
+            return method != null && method.IsPublic ? method : null;
+        }
+
+        /// <summary>
+        /// Returns the public setter of a property, or null if there is no such setter
+        /// (either because it's write-only, or the setter isn't public).
+        /// </summary>
+        internal static MethodInfo GetSetMethod(this PropertyInfo target)
+        {
+            var method = target.SetMethod;
+            return method != null && method.IsPublic ? method : null;
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf/Compatibility/RequiresUnreferencedCodeAttribute.cs

@@ -0,0 +1,72 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+#if !NET5_0_OR_GREATER
+// Copied with permission from https://github.com/dotnet/runtime/tree/8fbf206d0e518b45ca855832e8bfb391afa85972/src/libraries/System.Private.CoreLib/src/System/Diagnostics/CodeAnalysis
+namespace System.Diagnostics.CodeAnalysis
+{
+    /// <summary>
+    /// Indicates that the specified method requires dynamic access to code that is not referenced
+    /// statically, for example through <see cref="System.Reflection"/>.
+    /// </summary>
+    /// <remarks>
+    /// This allows tools to understand which methods are unsafe to call when removing unreferenced
+    /// code from an application.
+    /// </remarks>
+    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Constructor | AttributeTargets.Class, Inherited = false)]
+    internal sealed class RequiresUnreferencedCodeAttribute : Attribute
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="RequiresUnreferencedCodeAttribute"/> class
+        /// with the specified message.
+        /// </summary>
+        /// <param name="message">
+        /// A message that contains information about the usage of unreferenced code.
+        /// </param>
+        public RequiresUnreferencedCodeAttribute(string message)
+        {
+            Message = message;
+        }
+
+        /// <summary>
+        /// Gets a message that contains information about the usage of unreferenced code.
+        /// </summary>
+        public string Message { get; }
+
+        /// <summary>
+        /// Gets or sets an optional URL that contains more information about the method,
+        /// why it requires unreferenced code, and what options a consumer has to deal with it.
+        /// </summary>
+        public string Url { get; set; }
+    }
+}
+#endif

libs/protobuf/csharp/src/Google.Protobuf/Compatibility/TypeExtensions.cs

@@ -0,0 +1,113 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Reflection;
+
+namespace Google.Protobuf.Compatibility
+{
+    /// <summary>
+    /// Provides extension methods on Type that just proxy to TypeInfo.
+    /// These are used to support the new type system from .NET 4.5, without
+    /// having calls to GetTypeInfo all over the place. While the methods here are meant to be
+    /// broadly compatible with the desktop framework, there are some subtle differences in behaviour - but
+    /// they're not expected to affect our use cases. While the class is internal, that should be fine: we can
+    /// evaluate each new use appropriately.
+    /// </summary>
+    internal static class TypeExtensions
+    {
+        /// <summary>
+        /// See https://msdn.microsoft.com/en-us/library/system.type.isassignablefrom
+        /// </summary>
+        internal static bool IsAssignableFrom(this Type target, Type c)
+        {
+            return target.GetTypeInfo().IsAssignableFrom(c.GetTypeInfo());
+        }
+
+        /// <summary>
+        /// Returns a representation of the public property associated with the given name in the given type,
+        /// including inherited properties or null if there is no such public property.
+        /// Here, "public property" means a property where either the getter, or the setter, or both, is public.
+        /// </summary>
+        [UnconditionalSuppressMessage("Trimming", "IL2072",
+            Justification = "The BaseType of the target will have all properties because of the annotation.")]
+        internal static PropertyInfo GetProperty(
+            [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties | DynamicallyAccessedMemberTypes.NonPublicProperties)]
+            this Type target, string name)
+        {
+            // GetDeclaredProperty only returns properties declared in the given type, so we need to recurse.
+            while (target != null)
+            {
+                var typeInfo = target.GetTypeInfo();
+                var ret = typeInfo.GetDeclaredProperty(name);
+                if (ret != null && ((ret.CanRead && ret.GetMethod.IsPublic) || (ret.CanWrite && ret.SetMethod.IsPublic)))
+                {
+                    return ret;
+                }
+                target = typeInfo.BaseType;
+            }
+            return null;
+        }
+
+        /// <summary>
+        /// Returns a representation of the public method associated with the given name in the given type,
+        /// including inherited methods.
+        /// </summary>
+        /// <remarks>
+        /// This has a few differences compared with Type.GetMethod in the desktop framework. It will throw
+        /// if there is an ambiguous match even between a private method and a public one, but it *won't* throw
+        /// if there are two overloads at different levels in the type hierarchy (e.g. class Base declares public void Foo(int) and
+        /// class Child : Base declares public void Foo(long)).
+        /// </remarks>
+        /// <exception cref="AmbiguousMatchException">One type in the hierarchy declared more than one method with the same name</exception>
+        [UnconditionalSuppressMessage("Trimming", "IL2072",
+            Justification = "The BaseType of the target will have all properties because of the annotation.")]
+        internal static MethodInfo GetMethod(
+            [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods | DynamicallyAccessedMemberTypes.NonPublicMethods)]
+            this Type target, string name)
+        {
+            // GetDeclaredMethod only returns methods declared in the given type, so we need to recurse.
+            while (target != null)
+            {
+                var typeInfo = target.GetTypeInfo();
+                var ret = typeInfo.GetDeclaredMethod(name);
+                if (ret != null && ret.IsPublic)
+                {
+                    return ret;
+                }
+                target = typeInfo.BaseType;
+            }
+            return null;
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf/Compatibility/UnconditionalSuppressMessageAttribute.cs

@@ -0,0 +1,117 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+#if !NET5_0_OR_GREATER
+// Copied with permission from https://github.com/dotnet/runtime/tree/8fbf206d0e518b45ca855832e8bfb391afa85972/src/libraries/System.Private.CoreLib/src/System/Diagnostics/CodeAnalysis
+namespace System.Diagnostics.CodeAnalysis
+{
+    /// <summary>
+    /// Suppresses reporting of a specific rule violation, allowing multiple suppressions on a
+    /// single code artifact.
+    /// </summary>
+    /// <remarks>
+    /// <see cref="UnconditionalSuppressMessageAttribute"/> is different than
+    /// <see cref="SuppressMessageAttribute"/> in that it doesn't have a
+    /// <see cref="ConditionalAttribute"/>. So it is always preserved in the compiled assembly.
+    /// </remarks>
+    [AttributeUsage(AttributeTargets.All, Inherited = false, AllowMultiple = true)]
+    internal sealed class UnconditionalSuppressMessageAttribute : Attribute
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="UnconditionalSuppressMessageAttribute"/>
+        /// class, specifying the category of the tool and the identifier for an analysis rule.
+        /// </summary>
+        /// <param name="category">The category for the attribute.</param>
+        /// <param name="checkId">The identifier of the analysis rule the attribute applies to.</param>
+        public UnconditionalSuppressMessageAttribute(string category, string checkId)
+        {
+            Category = category;
+            CheckId = checkId;
+        }
+
+        /// <summary>
+        /// Gets the category identifying the classification of the attribute.
+        /// </summary>
+        /// <remarks>
+        /// The <see cref="Category"/> property describes the tool or tool analysis category
+        /// for which a message suppression attribute applies.
+        /// </remarks>
+        public string Category { get; }
+
+        /// <summary>
+        /// Gets the identifier of the analysis tool rule to be suppressed.
+        /// </summary>
+        /// <remarks>
+        /// Concatenated together, the <see cref="Category"/> and <see cref="CheckId"/>
+        /// properties form a unique check identifier.
+        /// </remarks>
+        public string CheckId { get; }
+
+        /// <summary>
+        /// Gets or sets the scope of the code that is relevant for the attribute.
+        /// </summary>
+        /// <remarks>
+        /// The Scope property is an optional argument that specifies the metadata scope for which
+        /// the attribute is relevant.
+        /// </remarks>
+        public string Scope { get; set; }
+
+        /// <summary>
+        /// Gets or sets a fully qualified path that represents the target of the attribute.
+        /// </summary>
+        /// <remarks>
+        /// The <see cref="Target"/> property is an optional argument identifying the analysis target
+        /// of the attribute. An example value is "System.IO.Stream.ctor():System.Void".
+        /// Because it is fully qualified, it can be long, particularly for targets such as parameters.
+        /// The analysis tool user interface should be capable of automatically formatting the parameter.
+        /// </remarks>
+        public string Target { get; set; }
+
+        /// <summary>
+        /// Gets or sets an optional argument expanding on exclusion criteria.
+        /// </summary>
+        /// <remarks>
+        /// The <see cref="MessageId "/> property is an optional argument that specifies additional
+        /// exclusion where the literal metadata target is not sufficiently precise. For example,
+        /// the <see cref="UnconditionalSuppressMessageAttribute"/> cannot be applied within a method,
+        /// and it may be desirable to suppress a violation against a statement in the method that will
+        /// give a rule violation, but not against all statements in the method.
+        /// </remarks>
+        public string MessageId { get; set; }
+
+        /// <summary>
+        /// Gets or sets the justification for suppressing the code analysis message.
+        /// </summary>
+        public string Justification { get; set; }
+    }
+}
+#endif

libs/protobuf/csharp/src/Google.Protobuf/Extension.cs

@@ -0,0 +1,119 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Represents a non-generic extension definition. This API is experimental and subject to change.
+    /// </summary>
+    public abstract class Extension
+    {
+        internal abstract Type TargetType { get; }
+
+        /// <summary>
+        /// Internal use. Creates a new extension with the specified field number.
+        /// </summary>
+        protected Extension(int fieldNumber)
+        {
+            FieldNumber = fieldNumber;
+        }
+
+        internal abstract IExtensionValue CreateValue();
+
+        /// <summary>
+        /// Gets the field number of this extension
+        /// </summary>
+        public int FieldNumber { get; }
+
+        internal abstract bool IsRepeated { get; }
+    }
+
+    /// <summary>
+    /// Represents a type-safe extension identifier used for getting and setting single extension values in <see cref="IExtendableMessage{T}"/> instances. 
+    /// This API is experimental and subject to change.
+    /// </summary>
+    /// <typeparam name="TTarget">The message type this field applies to</typeparam>
+    /// <typeparam name="TValue">The field value type of this extension</typeparam>
+    public sealed class Extension<TTarget, TValue> : Extension where TTarget : IExtendableMessage<TTarget>
+    {
+        private readonly FieldCodec<TValue> codec;
+
+        /// <summary>
+        /// Creates a new extension identifier with the specified field number and codec
+        /// </summary>
+        public Extension(int fieldNumber, FieldCodec<TValue> codec) : base(fieldNumber)
+        {
+            this.codec = codec;
+        }
+
+        internal TValue DefaultValue => codec != null ? codec.DefaultValue : default;
+
+        internal override Type TargetType => typeof(TTarget);
+
+        internal override bool IsRepeated => false;
+
+        internal override IExtensionValue CreateValue()
+        {
+            return new ExtensionValue<TValue>(codec);
+        }
+    }
+
+    /// <summary>
+    /// Represents a type-safe extension identifier used for getting repeated extension values in <see cref="IExtendableMessage{T}"/> instances.
+    /// This API is experimental and subject to change.
+    /// </summary>
+    /// <typeparam name="TTarget">The message type this field applies to</typeparam>
+    /// <typeparam name="TValue">The repeated field value type of this extension</typeparam>
+    public sealed class RepeatedExtension<TTarget, TValue> : Extension where TTarget : IExtendableMessage<TTarget>
+    {
+        private readonly FieldCodec<TValue> codec;
+
+        /// <summary>
+        /// Creates a new repeated extension identifier with the specified field number and codec
+        /// </summary>
+        public RepeatedExtension(int fieldNumber, FieldCodec<TValue> codec) : base(fieldNumber)
+        {
+            this.codec = codec;
+        }
+
+        internal override Type TargetType => typeof(TTarget);
+
+        internal override bool IsRepeated => true;
+
+        internal override IExtensionValue CreateValue()
+        {
+            return new RepeatedExtensionValue<TValue>(codec);
+        }
+    }
+}

libs/protobuf/csharp/src/Google.Protobuf/ExtensionRegistry.cs

@@ -0,0 +1,184 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Provides extensions to messages while parsing. This API is experimental and subject to change.
+    /// </summary>
+    public sealed class ExtensionRegistry : ICollection<Extension>, IDeepCloneable<ExtensionRegistry>
+    {
+        internal sealed class ExtensionComparer : IEqualityComparer<Extension>
+        {
+            public bool Equals(Extension a, Extension b)
+            {
+                return new ObjectIntPair<Type>(a.TargetType, a.FieldNumber).Equals(new ObjectIntPair<Type>(b.TargetType, b.FieldNumber));
+            }
+            public int GetHashCode(Extension a)
+            {
+                return new ObjectIntPair<Type>(a.TargetType, a.FieldNumber).GetHashCode();
+            }
+
+            internal static ExtensionComparer Instance = new ExtensionComparer();
+        }
+        private readonly IDictionary<ObjectIntPair<Type>, Extension> extensions;
+
+        /// <summary>
+        /// Creates a new empty extension registry
+        /// </summary>
+        public ExtensionRegistry()
+        {
+            extensions = new Dictionary<ObjectIntPair<Type>, Extension>();
+        }
+
+        private ExtensionRegistry(IDictionary<ObjectIntPair<Type>, Extension> collection)
+        {
+            extensions = collection.ToDictionary(k => k.Key, v => v.Value);
+        }
+
+        /// <summary>
+        /// Gets the total number of extensions in this extension registry
+        /// </summary>
+        public int Count => extensions.Count;
+
+        /// <summary>
+        /// Returns whether the registry is readonly
+        /// </summary>
+        bool ICollection<Extension>.IsReadOnly => false;
+
+        internal bool ContainsInputField(uint lastTag, Type target, out Extension extension)
+        {
+            return extensions.TryGetValue(new ObjectIntPair<Type>(target, WireFormat.GetTagFieldNumber(lastTag)), out extension);
+        }
+
+        /// <summary>
+        /// Adds the specified extension to the registry
+        /// </summary>
+        public void Add(Extension extension)
+        {
+            ProtoPreconditions.CheckNotNull(extension, nameof(extension));
+
+            extensions.Add(new ObjectIntPair<Type>(extension.TargetType, extension.FieldNumber), extension);
+        }
+
+        /// <summary>
+        /// Adds the specified extensions to the registry
+        /// </summary>
+        public void AddRange(IEnumerable<Extension> extensions)
+        {
+            ProtoPreconditions.CheckNotNull(extensions, nameof(extensions));
+
+            foreach (var extension in extensions)
+            {
+                Add(extension);
+            }
+        }
+
+        /// <summary>
+        /// Clears the registry of all values
+        /// </summary>
+        public void Clear()
+        {
+            extensions.Clear();
+        }
+
+        /// <summary>
+        /// Gets whether the extension registry contains the specified extension
+        /// </summary>
+        public bool Contains(Extension item)
+        {
+            ProtoPreconditions.CheckNotNull(item, nameof(item));
+
+            return extensions.ContainsKey(new ObjectIntPair<Type>(item.TargetType, item.FieldNumber));
+        }
+
+        /// <summary>
+        /// Copies the arrays in the registry set to the specified array at the specified index
+        /// </summary>
+        /// <param name="array">The array to copy to</param>
+        /// <param name="arrayIndex">The array index to start at</param>
+        void ICollection<Extension>.CopyTo(Extension[] array, int arrayIndex)
+        {
+            ProtoPreconditions.CheckNotNull(array, nameof(array));
+            if (arrayIndex < 0 || arrayIndex >= array.Length)
+            {
+                throw new ArgumentOutOfRangeException(nameof(arrayIndex));
+            }
+            if (array.Length - arrayIndex < Count)
+            {
+                throw new ArgumentException("The provided array is shorter than the number of elements in the registry");
+            }
+
+            for (int i = 0; i < array.Length; i++)
+            {
+                Extension extension = array[i];
+                extensions.Add(new ObjectIntPair<Type>(extension.TargetType, extension.FieldNumber), extension);
+            }
+        }
+
+        /// <summary>
+        /// Returns an enumerator to enumerate through the items in the registry
+        /// </summary>
+        /// <returns>Returns an enumerator for the extensions in this registry</returns>
+        public IEnumerator<Extension> GetEnumerator()
+        {
+            return extensions.Values.GetEnumerator();
+        }
+
+        /// <summary>
+        /// Removes the specified extension from the set
+        /// </summary>
+        /// <param name="item">The extension</param>
+        /// <returns><c>true</c> if the extension was removed, otherwise <c>false</c></returns>
+        public bool Remove(Extension item)
+        {
+            ProtoPreconditions.CheckNotNull(item, nameof(item));
+
+            return extensions.Remove(new ObjectIntPair<Type>(item.TargetType, item.FieldNumber));
+        }
+
+        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+
+        /// <summary>
+        /// Clones the registry into a new registry
+        /// </summary>
+        public ExtensionRegistry Clone()
+        {
+            return new ExtensionRegistry(extensions);
+        }
+    }
+}