carbon-lang/.bazelrc

# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
# Exceptions. See /LICENSE for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

build --crosstool_top=@bazel_cc_toolchain
build --host_crosstool_top=@bazel_cc_toolchain

# Default to using a disk cache to minimize re-building LLVM and Clang which we
# try to avoid updating too frequently to minimize rebuild cost. The location
# here can be overridden in the user configuration where needed.
#
# Note that this cache will grow without bound currently. You should
# periodically run the `scripts/clean_disk_cache.sh` script or some equivalent.
# https://github.com/bazelbuild/bazel/issues/5139 tracks fixing this in Bazel.
build --disk_cache=~/.cache/carbon-lang-build-cache

# Enable some safety when using the build cache, likely to be defaulted in
# future Bazel releases.
build --experimental_guard_against_concurrent_changes

# Allow the toolchain to configure itself differently in the host build from
# the target build. Even when the host and target platforms are ostensibly the
# same (and use identical toolchains), it is beneficial to be able to configure
# the specific toolchain features enabled for the target separately from the
# host. For example, sanitizers make sense for the target significantly more
# than for the host.
#
# Bazel bug tracking undoing the default here:
# https://github.com/bazelbuild/bazel/issues/13315
build --incompatible_dont_enable_host_nonhost_crosstool_features=false

# Disable warnings for all external compilations. These involve code that isn't
# developed as part of Carbon and may be difficult or impossible to patch, so
# warnings aren't likely to be actionable.
build --per_file_copt=external/.*\.(c|cc|cpp|cxx)$@-w
build --host_per_file_copt=external/.*\.(c|cc|cpp|cxx)$@-w

# Default dynamic linking to off. While this can help build performance in some
# edge cases with very large linked executables and a slow linker, between using
# fast linkers on all platforms (LLD and the Apple linker), as well as having
# relatively few such executables, shared objects simply waste too much space in
# our builds.
build --dynamic_mode=off

# Always compile PIC code. There are few if any disadvantages on the platforms
# and architectures we care about and it avoids the need to compile files twice.
build --force_pic

# Completely disable Bazel's automatic stripping of debug information. Removing
# that information causes unhelpful backtraces from unittest failures and other
# crashes. Optimized builds already avoid using debug information by default.
build --strip=never

# Enable Abseil for GoogleTest.
build --define=absl=1

# Configuration for enabling Address Sanitizer. Note that this is enabled by
# default for fastbuild. The config is provided to enable ASan even in
# optimized or other build configurations.
build:asan --features=asan

# Configuration for enabling LibFuzzer (along with ASan).
build:fuzzer --features=fuzzer

# Always allow tests to symbolize themselves with whatever `llvm-symbolize` is
# in the users environment.
build --test_env=ASAN_SYMBOLIZER_PATH

# Force actions to have a UTF-8 language encoding.
# TODO: Need to investigate what this should be on Windows, but at least for
# Linux and macOS this seems strictly better than the Bazel default of just
# `en_US`.
build --action_env=LANG=en_US.UTF-8

# Allow users to override any of the flags desired by importing a user-specific
# RC file here if present.
try-import %workspace%/user.bazelrc