# 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 # """Implementation of the proto_lang_toolchain rule.""" load("@proto_bazel_features//:features.bzl", "bazel_features") load("//bazel/common:proto_common.bzl", "proto_common") load("//bazel/common:proto_info.bzl", "ProtoInfo") load("//bazel/common:proto_lang_toolchain_info.bzl", "ProtoLangToolchainInfo") load("//bazel/private:toolchain_helpers.bzl", "toolchains") def _rule_impl(ctx): provided_proto_sources = depset(transitive = [bp[ProtoInfo]._transitive_proto_sources for bp in ctx.attr.blacklisted_protos]).to_list() flag = ctx.attr.command_line if flag.find("$(PLUGIN_OUT)") > -1: fail("in attribute 'command_line': Placeholder '$(PLUGIN_OUT)' is not supported.") flag = flag.replace("$(OUT)", "%s") plugin = None if ctx.attr.plugin != None: plugin = ctx.attr.plugin[DefaultInfo].files_to_run if proto_common.INCOMPATIBLE_ENABLE_PROTO_TOOLCHAIN_RESOLUTION: proto_compiler = ctx.toolchains[toolchains.PROTO_TOOLCHAIN].proto.proto_compiler protoc_opts = ctx.toolchains[toolchains.PROTO_TOOLCHAIN].proto.protoc_opts else: proto_compiler = ctx.attr._proto_compiler.files_to_run protoc_opts = ctx.fragments.proto.experimental_protoc_opts if ctx.attr.protoc_minimal_do_not_use: proto_compiler = ctx.attr.protoc_minimal_do_not_use.files_to_run proto_lang_toolchain_info = ProtoLangToolchainInfo( out_replacement_format_flag = flag, output_files = ctx.attr.output_files, plugin_format_flag = ctx.attr.plugin_format_flag, plugin = plugin, runtime = ctx.attr.runtime, provided_proto_sources = provided_proto_sources, proto_compiler = proto_compiler, protoc_opts = protoc_opts, progress_message = ctx.attr.progress_message, mnemonic = ctx.attr.mnemonic, allowlist_different_package = ctx.attr.allowlist_different_package, toolchain_type = ctx.attr.toolchain_type.label if ctx.attr.toolchain_type else None, ) return [ DefaultInfo(files = depset(), runfiles = ctx.runfiles()), platform_common.ToolchainInfo(proto = proto_lang_toolchain_info), # TODO: remove when --incompatible_enable_proto_toolchains is flipped and removed proto_lang_toolchain_info, ] proto_lang_toolchain = rule( _rule_impl, doc = """

If using Bazel, please load the rule from https://github.com/bazelbuild/rules_proto.

Specifies how a LANG_proto_library rule (e.g., java_proto_library) should invoke the proto-compiler. Some LANG_proto_library rules allow specifying which toolchain to use using command-line flags; consult their documentation.

Normally you should not write those kind of rules unless you want to tune your Java compiler.

There's no compiler. The proto-compiler is taken from the proto_library rule we attach to. It is passed as a command-line flag to Blaze. Several features require a proto-compiler to be invoked on the proto_library rule itself. It's beneficial to enforce the compiler that LANG_proto_library uses is the same as the one proto_library does.

Examples

A simple example would be: 


proto_lang_toolchain(
    name = "javalite_toolchain",
    command_line = "--javalite_out=shared,immutable:$(OUT)",
    plugin = ":javalite_plugin",
    runtime = ":protobuf_lite",
)
""", attrs = { "progress_message": attr.string(default = "Generating proto_library %{label}", doc = """ This value will be set as the progress message on protoc action."""), "mnemonic": attr.string(default = "GenProto", doc = """ This value will be set as the mnemonic on protoc action."""), "command_line": attr.string(mandatory = True, doc = """ This value will be passed to proto-compiler to generate the code. Only include the parts specific to this code-generator/plugin (e.g., do not include -I parameters) """), "output_files": attr.string(values = ["single", "multiple", "legacy"], default = "legacy", doc = """ Controls how $(OUT) in command_line is formatted, either by a path to a single file or output directory in case of multiple files. Possible values are: "single", "multiple"."""), "plugin_format_flag": attr.string(doc = """ If provided, this value will be passed to proto-compiler to use the plugin. The value must contain a single %s which is replaced with plugin executable. --plugin=protoc-gen-PLUGIN=<executable>."""), "plugin": attr.label( executable = True, cfg = "exec", doc = """ If provided, will be made available to the action that calls the proto-compiler, and will be passed to the proto-compiler: --plugin=protoc-gen-PLUGIN=<executable>.""", ), "runtime": attr.label(doc = """ A language-specific library that the generated code is compiled against. The exact behavior is LANG_proto_library-specific. Java, for example, should compile against the runtime."""), "blacklisted_protos": attr.label_list( providers = [ProtoInfo], doc = """ No code will be generated for files in the srcs attribute of blacklisted_protos. This is used for .proto files that are already linked into proto runtimes, such as any.proto.""", ), # TODO: add doc "allowlist_different_package": attr.label( cfg = "exec", providers = [bazel_features.globals.PackageSpecificationInfo] if bazel_features.globals.PackageSpecificationInfo else [], ), # TODO: add doc "toolchain_type": attr.label(), # DO NOT USE. For Protobuf incremental changes only: b/305068148. "protoc_minimal_do_not_use": attr.label( cfg = "exec", executable = True, ), } | ({} if proto_common.INCOMPATIBLE_ENABLE_PROTO_TOOLCHAIN_RESOLUTION else { "_proto_compiler": attr.label( cfg = "exec", executable = True, allow_files = True, default = configuration_field("proto", "proto_compiler"), ), }), provides = [ProtoLangToolchainInfo], fragments = ["proto"], toolchains = toolchains.use_toolchain(toolchains.PROTO_TOOLCHAIN), # Used to obtain protoc )