build/toolchain/cc_toolchain_config.bzl

#  Copyright 2020 The Monogon Project Authors.
#
#  SPDX-License-Identifier: Apache-2.0
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.

load("@bazel_tools//tools/cpp:cc_toolchain_config_lib.bzl", "feature", "flag_group", "flag_set", "tool", "tool_path")
load("@bazel_tools//tools/build_defs/cc:action_names.bzl", "ACTION_NAMES")

all_compile_actions = [
    ACTION_NAMES.c_compile,
    ACTION_NAMES.cpp_compile,
    ACTION_NAMES.linkstamp_compile,
    ACTION_NAMES.assemble,
    ACTION_NAMES.preprocess_assemble,
    ACTION_NAMES.cpp_header_parsing,
    ACTION_NAMES.cpp_module_compile,
    ACTION_NAMES.cpp_module_codegen,
    ACTION_NAMES.clif_match,
    ACTION_NAMES.lto_backend,
]

all_cpp_compile_actions = [
    ACTION_NAMES.cpp_compile,
    ACTION_NAMES.linkstamp_compile,
    ACTION_NAMES.cpp_header_parsing,
    ACTION_NAMES.cpp_module_compile,
    ACTION_NAMES.cpp_module_codegen,
    ACTION_NAMES.clif_match,
]

preprocessor_compile_actions = [
    ACTION_NAMES.c_compile,
    ACTION_NAMES.cpp_compile,
    ACTION_NAMES.linkstamp_compile,
    ACTION_NAMES.preprocess_assemble,
    ACTION_NAMES.cpp_header_parsing,
    ACTION_NAMES.cpp_module_compile,
    ACTION_NAMES.clif_match,
]

codegen_compile_actions = [
    ACTION_NAMES.c_compile,
    ACTION_NAMES.cpp_compile,
    ACTION_NAMES.linkstamp_compile,
    ACTION_NAMES.assemble,
    ACTION_NAMES.preprocess_assemble,
    ACTION_NAMES.cpp_module_codegen,
    ACTION_NAMES.lto_backend,
]

all_link_actions = [
    ACTION_NAMES.cpp_link_executable,
    ACTION_NAMES.cpp_link_dynamic_library,
    ACTION_NAMES.cpp_link_nodeps_dynamic_library,
]

lto_index_actions = [
    ACTION_NAMES.lto_index_for_executable,
    ACTION_NAMES.lto_index_for_dynamic_library,
    ACTION_NAMES.lto_index_for_nodeps_dynamic_library,
]

# This defines a minimal, barely parametrized toolchain configuration rule that
# uses the host GCC with some possible overrides.

def _host_cc_toolchain_impl(ctx):
    cpp_feature = feature(
        name = "cpp",
        enabled = ctx.attr.has_cpp,
        flag_sets = [
            flag_set(
                actions = all_cpp_compile_actions + [ACTION_NAMES.lto_backend],
                flag_groups = ([
                    flag_group(
                        flags = ["-std=c++17"],
                    ),
                ]),
            ),
            flag_set(
                actions = all_link_actions + lto_index_actions,
                flag_groups = ([
                    flag_group(
                        flags = [
                            "-lstdc++",
                        ],
                    ),
                ]),
            ),
        ],
    )
    link_full_libc_feature = feature(
        name = "link_full_libc",
        enabled = True,
        flag_sets = [
            flag_set(
                actions = all_link_actions + lto_index_actions,
                flag_groups = ([
                    flag_group(
                        flags = [
                            "-lm",
                            "-lutil",
                            "-lpthread",
                        ],
                    ),
                ] if ctx.attr.is_glibc else []),  # musl just works
            ),
        ],
    )
    default_link_flags_feature = feature(
        name = "default_link_flags",
        enabled = True,
        flag_sets = [
            flag_set(
                actions = all_link_actions + lto_index_actions,
                flag_groups = ([
                    flag_group(
                        flags = [
                            "-Wl,-z,relro,-z,now",
                            "-pass-exit-codes",
                        ],
                    ),
                ]),
            ),
        ],
    )
    tool_paths = [
        tool_path(
            name = "gcc",
            path = ctx.attr.gcc,
        ),
        tool_path(
            name = "ld",
            path = "/usr/bin/ld",
        ),
        tool_path(
            name = "ar",
            path = "/usr/bin/ar",
        ),
        tool_path(
            name = "cpp",
            path = "/bin/false",
        ),
        tool_path(
            name = "gcov",
            path = "/bin/false",
        ),
        tool_path(
            name = "nm",
            path = "/bin/false",
        ),
        tool_path(
            name = "objdump",
            path = "/bin/false",
        ),
        tool_path(
            name = "strip",
            path = "/bin/false",
        ),
    ]

    return cc_common.create_cc_toolchain_config_info(
        ctx = ctx,
        features = [default_link_flags_feature, link_full_libc_feature, cpp_feature],
        cxx_builtin_include_directories = ctx.attr.host_includes,
        toolchain_identifier = "k8-toolchain",
        host_system_name = "local",
        target_system_name = "local",
        target_cpu = "k8",
        target_libc = "unknown",
        compiler = "gcc",
        abi_version = "unknown",
        abi_libc_version = "unknown",
        tool_paths = tool_paths,
        builtin_sysroot = ctx.attr.sysroot,
    )

host_cc_toolchain_config = rule(
    implementation = _host_cc_toolchain_impl,
    attrs = {
        "gcc": attr.string(
            default = "/usr/bin/gcc",
        ),
        "has_cpp": attr.bool(default = True),
        "is_glibc": attr.bool(default = True),
        "host_includes": attr.string_list(
            default = [
                "/usr/lib/gcc/x86_64-redhat-linux/12/include/",
                "/usr/include",
            ],
        ),
        "sysroot": attr.string(
            default = "",
        ),
    },
    provides = [CcToolchainConfigInfo],
)