Squashed 'libs/protobuf/' content from commit fcd3b9a85
git-subtree-dir: libs/protobuf git-subtree-split: fcd3b9a85ef36e46643dc30176cea1a7ad62e02b
This commit is contained in:
400
pkg/cc_dist_library.bzl
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400
pkg/cc_dist_library.bzl
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# Rules for distributable C++ libraries
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load("@rules_cc//cc:action_names.bzl", cc_action_names = "ACTION_NAMES")
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load("@rules_cc//cc:find_cc_toolchain.bzl", "find_cc_toolchain")
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################################################################################
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# Archive/linking support
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################################################################################
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def _collect_linker_input_objects(dep_label, cc_info, objs, pic_objs):
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"""Accumulate .o and .pic.o files into `objs` and `pic_objs`."""
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link_ctx = cc_info.linking_context
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if link_ctx == None:
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return
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linker_inputs = link_ctx.linker_inputs.to_list()
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for link_input in linker_inputs:
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if link_input.owner != dep_label:
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# This is a transitive dep: skip it.
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continue
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for lib in link_input.libraries:
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objs.extend(lib.objects or [])
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pic_objs.extend(lib.pic_objects or [])
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# Creates an action to build the `output_file` static library (archive)
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# using `object_files`.
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def _create_archive_action(
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ctx,
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feature_configuration,
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cc_toolchain_info,
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output_file,
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object_files):
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# Based on Bazel's src/main/starlark/builtins_bzl/common/cc/cc_import.bzl:
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# Build the command line and add args for all of the input files:
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archiver_variables = cc_common.create_link_variables(
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feature_configuration = feature_configuration,
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cc_toolchain = cc_toolchain_info,
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output_file = output_file.path,
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is_using_linker = False,
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)
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command_line = cc_common.get_memory_inefficient_command_line(
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feature_configuration = feature_configuration,
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action_name = cc_action_names.cpp_link_static_library,
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variables = archiver_variables,
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)
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args = ctx.actions.args()
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args.add_all(command_line)
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args.add_all(object_files)
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args.use_param_file("@%s", use_always = True)
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archiver_path = cc_common.get_tool_for_action(
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feature_configuration = feature_configuration,
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action_name = cc_action_names.cpp_link_static_library,
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)
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env = cc_common.get_environment_variables(
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feature_configuration = feature_configuration,
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action_name = cc_action_names.cpp_link_static_library,
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variables = archiver_variables,
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)
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ctx.actions.run(
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executable = archiver_path,
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arguments = [args],
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env = env,
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inputs = depset(
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direct = object_files,
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transitive = [
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cc_toolchain_info.all_files,
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],
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),
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use_default_shell_env = False,
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outputs = [output_file],
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mnemonic = "CppArchiveDist",
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)
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def _create_dso_link_action(
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ctx,
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feature_configuration,
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cc_toolchain_info,
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object_files,
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pic_object_files):
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compilation_outputs = cc_common.create_compilation_outputs(
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objects = depset(object_files),
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pic_objects = depset(pic_object_files),
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)
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link_output = cc_common.link(
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actions = ctx.actions,
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feature_configuration = feature_configuration,
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cc_toolchain = cc_toolchain_info,
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compilation_outputs = compilation_outputs,
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name = ctx.label.name,
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output_type = "dynamic_library",
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user_link_flags = ctx.attr.linkopts,
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)
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library_to_link = link_output.library_to_link
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outputs = []
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# Note: library_to_link.dynamic_library and interface_library are often
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# symlinks in the solib directory. For DefaultInfo, prefer reporting
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# the resolved artifact paths.
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if library_to_link.resolved_symlink_dynamic_library != None:
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outputs.append(library_to_link.resolved_symlink_dynamic_library)
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elif library_to_link.dynamic_library != None:
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outputs.append(library_to_link.dynamic_library)
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if library_to_link.resolved_symlink_interface_library != None:
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outputs.append(library_to_link.resolved_symlink_interface_library)
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elif library_to_link.interface_library != None:
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outputs.append(library_to_link.interface_library)
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return outputs
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################################################################################
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# Source file/header support
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################################################################################
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CcFileList = provider(
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doc = "List of files to be built into a library.",
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fields = {
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# As a rule of thumb, `hdrs` and `textual_hdrs` are the files that
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# would be installed along with a prebuilt library.
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"hdrs": "public header files, including those used by generated code",
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"textual_hdrs": "files which are included but are not self-contained",
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# The `internal_hdrs` are header files which appear in `srcs`.
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# These are only used when compiling the library.
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"internal_hdrs": "internal header files (only used to build .cc files)",
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"srcs": "source files",
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},
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)
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def _flatten_target_files(targets):
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return depset(transitive = [target.files for target in targets])
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files = []
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for target in targets:
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files.extend(target.files.to_list())
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return files
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def _cc_file_list_aspect_impl(target, ctx):
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# Extract sources from a `cc_library` (or similar):
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if CcInfo not in target:
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return []
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# We're going to reach directly into the attrs on the traversed rule.
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rule_attr = ctx.rule.attr
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# CcInfo is a proxy for what we expect this rule to look like.
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# However, some deps may expose `CcInfo` without having `srcs`,
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# `hdrs`, etc., so we use `getattr` to handle that gracefully.
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internal_hdrs = []
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srcs = []
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# Filter `srcs` so it only contains source files. Headers will go
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# into `internal_headers`.
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for src in _flatten_target_files(getattr(rule_attr, "srcs", [])).to_list():
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if src.extension.lower() in ["c", "cc", "cpp", "cxx"]:
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srcs.append(src)
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else:
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internal_hdrs.append(src)
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return [CcFileList(
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hdrs = _flatten_target_files(getattr(rule_attr, "hdrs", depset())),
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textual_hdrs = _flatten_target_files(getattr(
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rule_attr,
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"textual_hdrs",
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depset(),
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)),
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internal_hdrs = depset(internal_hdrs),
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srcs = depset(srcs),
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)]
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cc_file_list_aspect = aspect(
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doc = """
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Aspect to provide the list of sources and headers from a rule.
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Output is CcFileList. Example:
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cc_library(
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name = "foo",
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srcs = [
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"foo.cc",
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"foo_internal.h",
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],
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hdrs = ["foo.h"],
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textual_hdrs = ["foo_inl.inc"],
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)
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# produces:
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# CcFileList(
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# hdrs = depset([File("foo.h")]),
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# textual_hdrs = depset([File("foo_inl.inc")]),
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# internal_hdrs = depset([File("foo_internal.h")]),
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# srcs = depset([File("foo.cc")]),
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# )
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""",
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implementation = _cc_file_list_aspect_impl,
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)
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################################################################################
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# Rule impl
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################################################################################
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def _collect_inputs(deps):
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"""Collects files from a list of immediate deps.
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This rule collects source files and linker inputs for C++ deps. Only
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these immediate deps are considered, not transitive deps.
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The return value is a struct with object files (linker inputs),
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partitioned by PIC and non-pic, and the rules' source and header files:
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struct(
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objects = ..., # non-PIC object files
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pic_objects = ..., # PIC objects
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cc_file_list = ..., # a CcFileList
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)
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Args:
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deps: Iterable of immediate deps. These will be treated as the "inputs,"
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but not the transitive deps.
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Returns:
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A struct with linker inputs, source files, and header files.
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"""
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objs = []
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pic_objs = []
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# The returned CcFileList will contain depsets of the deps' file lists.
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# These lists hold `depset()`s from each of `deps`.
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srcs = []
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hdrs = []
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internal_hdrs = []
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textual_hdrs = []
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for dep in deps:
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if CcInfo in dep:
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_collect_linker_input_objects(
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dep.label,
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dep[CcInfo],
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objs,
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pic_objs,
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)
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if CcFileList in dep:
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cfl = dep[CcFileList]
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srcs.append(cfl.srcs)
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hdrs.append(cfl.hdrs)
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internal_hdrs.append(cfl.internal_hdrs)
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textual_hdrs.append(cfl.textual_hdrs)
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return struct(
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objects = objs,
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pic_objects = pic_objs,
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cc_file_list = CcFileList(
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srcs = depset(transitive = srcs),
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hdrs = depset(transitive = hdrs),
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internal_hdrs = depset(transitive = internal_hdrs),
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textual_hdrs = depset(transitive = textual_hdrs),
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),
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)
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# Implementation for cc_dist_library rule.
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def _cc_dist_library_impl(ctx):
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cc_toolchain_info = find_cc_toolchain(ctx)
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feature_configuration = cc_common.configure_features(
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ctx = ctx,
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cc_toolchain = cc_toolchain_info,
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)
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inputs = _collect_inputs(ctx.attr.deps)
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# For static libraries, build separately with and without pic.
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stemname = "lib" + ctx.label.name
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outputs = []
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if len(inputs.objects) > 0:
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archive_out = ctx.actions.declare_file(stemname + ".a")
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_create_archive_action(
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ctx,
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feature_configuration,
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cc_toolchain_info,
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archive_out,
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inputs.objects,
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)
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outputs.append(archive_out)
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if len(inputs.pic_objects) > 0:
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pic_archive_out = ctx.actions.declare_file(stemname + ".pic.a")
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_create_archive_action(
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ctx,
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feature_configuration,
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cc_toolchain_info,
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pic_archive_out,
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inputs.pic_objects,
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)
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outputs.append(pic_archive_out)
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# For dynamic libraries, use the `cc_common.link` command to ensure
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# everything gets built correctly according to toolchain definitions.
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outputs.extend(_create_dso_link_action(
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ctx,
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feature_configuration,
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cc_toolchain_info,
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inputs.objects,
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inputs.pic_objects,
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))
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# We could expose the libraries for use from cc rules:
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#
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# linking_context = cc_common.create_linking_context(
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# linker_inputs = depset([
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# cc_common.create_linker_input(
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# owner = ctx.label,
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# libraries = depset([library_to_link]),
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# ),
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# ]),
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# )
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# cc_info = CcInfo(linking_context = linking_context) # and return this
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#
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# However, if the goal is to force a protobuf dependency to use the
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# DSO, then `cc_import` is a better-supported way to do so.
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#
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# If we wanted to expose CcInfo from this rule (and make it usable as a
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# C++ dependency), then we would probably want to include the static
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# archive and headers as well. exposing headers would probably require
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# an additional aspect to extract CcInfos with just the deps' headers.
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return [
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DefaultInfo(files = depset(outputs)),
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inputs.cc_file_list,
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]
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cc_dist_library = rule(
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implementation = _cc_dist_library_impl,
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doc = """
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Create libraries suitable for distribution.
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This rule creates static and dynamic libraries from the libraries listed in
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'deps'. The resulting libraries are suitable for distributing all of 'deps'
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in a single logical library, for example, in an installable binary package.
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Only the targets listed in 'deps' are included in the result (i.e., the
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output does not include transitive dependencies), allowing precise control
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over the library boundary.
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The outputs of this rule are a dynamic library and a static library. (If
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the build produces both PIC and non-PIC object files, then there is also a
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second static library.) The example below illustrates additional details.
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This rule is different from Bazel's experimental `shared_cc_library` in
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several ways. First, this rule ignores transitive dependencies, which means
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that dynamic library dependencies generally need to be specified via
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'linkopts'. Second, this rule produces a static archive library in addition
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to the dynamic shared library. Third, this rule is not directly usable as a
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C++ dependency (although the outputs could be used, e.g., by `cc_import`).
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Example:
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cc_library(name = "a", srcs = ["a.cc"], hdrs = ["a.h"])
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cc_library(name = "b", srcs = ["b.cc"], hdrs = ["b.h"], deps = [":a"])
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cc_library(name = "c", srcs = ["c.cc"], hdrs = ["c.h"], deps = [":b"])
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# Creates libdist.so and (typically) libdist.pic.a:
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# (This may also produce libdist.a if the build produces non-PIC objects.)
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cc_dist_library(
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name = "dist",
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linkopts = ["-la"], # libdist.so dynamically links against liba.so.
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deps = [":b", ":c"], # Output contains b.o and c.o, but not a.o.
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)
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""",
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attrs = {
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"deps": attr.label_list(
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doc = ("The list of libraries to be included in the outputs. " +
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"Only these targets' compilation outputs will be " +
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"included (i.e., the transitive dependencies are not " +
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"included in the output)."),
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aspects = [cc_file_list_aspect],
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),
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"linkopts": attr.string_list(
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doc = ("Add these flags to the C++ linker command when creating " +
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"the dynamic library."),
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),
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# C++ toolchain before https://github.com/bazelbuild/bazel/issues/7260:
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"_cc_toolchain": attr.label(
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default = Label("@rules_cc//cc:current_cc_toolchain"),
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),
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},
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toolchains = [
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# C++ toolchain after https://github.com/bazelbuild/bazel/issues/7260:
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"@bazel_tools//tools/cpp:toolchain_type",
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],
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fragments = ["cpp"],
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)
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Reference in New Issue
Block a user