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# Protocol Buffers - Google's data interchange format
# Copyright 2024 Google Inc. All rights reserved.
#
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file or at
# https://developers.google.com/open-source/licenses/bsd
#
"""Bazel's implementation of cc_proto_library"""
load("@rules_cc//cc:find_cc_toolchain.bzl", "use_cc_toolchain")
load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
load("//bazel/common:proto_common.bzl", "proto_common")
load("//bazel/common:proto_info.bzl", "ProtoInfo")
load("//bazel/private:cc_proto_support.bzl", "cc_proto_compile_and_link")
load("//bazel/private:toolchain_helpers.bzl", "toolchains")
_CC_PROTO_TOOLCHAIN = Label("//bazel/private:cc_toolchain_type")
_ProtoCcFilesInfo = provider(fields = ["files"], doc = "Provide cc proto files.")
_ProtoCcHeaderInfo = provider(fields = ["headers"], doc = "Provide cc proto headers.")
def _get_output_files(actions, proto_info, suffixes):
result = []
for suffix in suffixes:
result.extend(proto_common.declare_generated_files(
actions = actions,
proto_info = proto_info,
extension = suffix,
))
return result
# TODO: Make this code actually work.
def _get_strip_include_prefix(ctx, proto_info):
proto_root = proto_info.proto_source_root
if proto_root == "." or proto_root == ctx.label.workspace_root:
return ""
strip_include_prefix = ""
if proto_root.startswith(ctx.bin_dir.path):
proto_root = proto_root[len(ctx.bin_dir.path) + 1:]
elif proto_root.startswith(ctx.genfiles_dir.path):
proto_root = proto_root[len(ctx.genfiles_dir.path) + 1:]
if proto_root.startswith(ctx.label.workspace_root):
proto_root = proto_root[len(ctx.label.workspace_root):]
strip_include_prefix = "//" + proto_root
return strip_include_prefix
def _aspect_impl(target, ctx):
proto_info = target[ProtoInfo]
proto_configuration = ctx.fragments.proto
sources = []
headers = []
textual_hdrs = []
proto_toolchain = toolchains.find_toolchain(ctx, "_aspect_cc_proto_toolchain", _CC_PROTO_TOOLCHAIN)
should_generate_code = proto_common.experimental_should_generate_code(proto_info, proto_toolchain, "cc_proto_library", target.label)
if should_generate_code:
if len(proto_info.direct_sources) != 0:
# Bazel 7 didn't expose cc_proto_library_source_suffixes used by Kythe
# gradually falling back to .pb.cc
if type(proto_configuration.cc_proto_library_source_suffixes) == "builtin_function_or_method":
source_suffixes = [".pb.cc"]
header_suffixes = [".pb.h"]
else:
source_suffixes = proto_configuration.cc_proto_library_source_suffixes
header_suffixes = proto_configuration.cc_proto_library_header_suffixes
sources = _get_output_files(ctx.actions, proto_info, source_suffixes)
headers = _get_output_files(ctx.actions, proto_info, header_suffixes)
header_provider = _ProtoCcHeaderInfo(headers = depset(headers))
else:
# If this proto_library doesn't have sources, it provides the combined headers of all its
# direct dependencies. Thus, if a direct dependency does have sources, the generated files
# are also provided by this library. If a direct dependency does not have sources, it will
# do the same thing, so that effectively this library looks through all source-less
# proto_libraries and provides all generated headers of the proto_libraries with sources
# that it depends on.
transitive_headers = []
for dep in getattr(ctx.rule.attr, "deps", []):
if _ProtoCcHeaderInfo in dep:
textual_hdrs.extend(dep[_ProtoCcHeaderInfo].headers.to_list())
transitive_headers.append(dep[_ProtoCcHeaderInfo].headers)
header_provider = _ProtoCcHeaderInfo(headers = depset(transitive = transitive_headers))
else: # shouldn't generate code
header_provider = _ProtoCcHeaderInfo(headers = depset())
proto_common.compile(
actions = ctx.actions,
proto_info = proto_info,
proto_lang_toolchain_info = proto_toolchain,
generated_files = sources + headers,
experimental_output_files = "multiple",
)
deps = []
if proto_toolchain.runtime:
deps = [proto_toolchain.runtime]
deps.extend(getattr(ctx.rule.attr, "deps", []))
cc_info, libraries, temps = cc_proto_compile_and_link(
ctx = ctx,
deps = deps,
sources = sources,
headers = headers,
textual_hdrs = textual_hdrs,
strip_include_prefix = _get_strip_include_prefix(ctx, proto_info),
)
return [
cc_info,
_ProtoCcFilesInfo(files = depset(sources + headers + libraries)),
OutputGroupInfo(temp_files_INTERNAL_ = temps),
header_provider,
]
cc_proto_aspect = aspect(
implementation = _aspect_impl,
attr_aspects = ["deps"],
fragments = ["cpp", "proto"],
required_providers = [ProtoInfo],
provides = [CcInfo],
attrs = toolchains.if_legacy_toolchain({"_aspect_cc_proto_toolchain": attr.label(
default = configuration_field(fragment = "proto", name = "proto_toolchain_for_cc"),
)}),
toolchains = use_cc_toolchain() + toolchains.use_toolchain(_CC_PROTO_TOOLCHAIN),
)
def _cc_proto_library_impl(ctx):
if len(ctx.attr.deps) != 1:
fail(
"'deps' attribute must contain exactly one label " +
"(we didn't name it 'dep' for consistency). " +
"The main use-case for multiple deps is to create a rule that contains several " +
"other targets. This makes dependency bloat more likely. It also makes it harder" +
"to remove unused deps.",
attr = "deps",
)
dep = ctx.attr.deps[0]
proto_toolchain = toolchains.find_toolchain(ctx, "_aspect_cc_proto_toolchain", _CC_PROTO_TOOLCHAIN)
proto_common.check_collocated(ctx.label, dep[ProtoInfo], proto_toolchain)
return [DefaultInfo(files = dep[_ProtoCcFilesInfo].files), dep[CcInfo], dep[OutputGroupInfo]]
cc_proto_library = rule(
implementation = _cc_proto_library_impl,
doc = """
<p>
<code>cc_proto_library</code> generates C++ code from <code>.proto</code> files.
</p>
<p>
<code>deps</code> must point to <a href="protocol-buffer.html#proto_library"><code>proto_library
</code></a> rules.
</p>
<p>
Example:
</p>
<pre>
<code class="lang-starlark">
cc_library(
name = "lib",
deps = [":foo_cc_proto"],
)
cc_proto_library(
name = "foo_cc_proto",
deps = [":foo_proto"],
)
proto_library(
name = "foo_proto",
)
</code>
</pre>
""",
attrs = {
"deps": attr.label_list(
aspects = [cc_proto_aspect],
allow_rules = ["proto_library"],
allow_files = False,
doc = """
The list of <a href="protocol-buffer.html#proto_library"><code>proto_library</code></a>
rules to generate C++ code for.""",
),
} | toolchains.if_legacy_toolchain({
"_aspect_cc_proto_toolchain": attr.label(
default = configuration_field(fragment = "proto", name = "proto_toolchain_for_cc"),
),
}),
provides = [CcInfo],
toolchains = toolchains.use_toolchain(_CC_PROTO_TOOLCHAIN),
)
|
