bazel/private/proto_toolchain_rule.bzl

# 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
#
"""A Starlark implementation of the proto_toolchain rule."""

load("//bazel/common:proto_common.bzl", "proto_common")
load("//bazel/common:proto_lang_toolchain_info.bzl", "ProtoLangToolchainInfo")
load("//bazel/private:toolchain_helpers.bzl", "toolchains")

def _impl(ctx):
    return [
        DefaultInfo(
            files = depset(),
            runfiles = ctx.runfiles(),
        ),
        platform_common.ToolchainInfo(
            proto = ProtoLangToolchainInfo(
                out_replacement_format_flag = ctx.attr.command_line,
                output_files = ctx.attr.output_files,
                plugin = None,
                runtime = None,
                proto_compiler = ctx.attr.proto_compiler.files_to_run,
                protoc_opts = ctx.fragments.proto.experimental_protoc_opts,
                progress_message = ctx.attr.progress_message,
                mnemonic = ctx.attr.mnemonic,
                **(dict(toolchain_type = toolchains.PROTO_TOOLCHAIN) if proto_common.INCOMPATIBLE_PASS_TOOLCHAIN_TYPE else {})
            ),
        ),
    ]

proto_toolchain = rule(
    _impl,
    attrs =
        {
            "progress_message": attr.string(default = "Generating Descriptor Set proto_library %{label}"),
            "mnemonic": attr.string(default = "GenProtoDescriptorSet"),
            "command_line": attr.string(default = "--descriptor_set_out=%s"),
            "output_files": attr.string(values = ["single", "multiple", "legacy"], default = "single"),
            "proto_compiler": attr.label(
                cfg = "exec",
                executable = True,
                allow_files = True,  # Used by mocks in tests. Consider fixing tests and removing it.
            ),
        },
    provides = [platform_common.ToolchainInfo],
    fragments = ["proto"],
)