macos-gcc.bazelrc

# Copyright 2025 Philipp Stephani
#
# 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.

# Support for building with GCC on macOS.  Ideally “CC=gcc-14” would suffice,
# but there seem to be various bugs in GCC and rules_cc that we need to work
# around.

# By default, rules_cc unconditionally links in libc++ on macOS (see
# configure_unix_toolchain in //cc/private/toolchain:unix_cc_configure.bzl), but
# with GCC the headers come from libstdc++, causing link failures.  Force
# linking with libstdc++ instead.  This needs to happen via BAZEL_LINKLIBS to
# override the default set in configure_unix_toolchain.
# TODO: File bug against rules_cc.  It shouldn’t default to libstd++ when
# compiling with GCC.
common:macos-gcc --repo_env='BAZEL_LINKLIBS=-lstdc++'

# Without _DARWIN_C_SOURCE, including cstdlib from libstdc++ fails if
# _POSIX_C_SOURCE is defined.  See the logic in
# /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/cdefs.h
# and /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_stdlib.h.
# TODO: File bug against Homebrew and/or GCC.
build:macos-gcc --copt='-D_DARWIN_C_SOURCE' --host_copt='-D_DARWIN_C_SOURCE'

# The macos_default_link_flags feature unconditionally adds -fobjc-link-runtime,
# which isn’t supported by GCC.
# TODO: File bug against rules_cc.
build:macos-gcc --features='-macos_default_link_flags'
build:macos-gcc --host_features='-macos_default_link_flags'

# Local Variables:
# mode: bazelrc
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