utils/bazel/.bazelrc

# This file is licensed under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

###############################################################################
# Common flags that apply to all configurations.
# Use sparingly for things common to all compilers and platforms.
###############################################################################

# Flip off to disable MODULE.bazel until we're ready.
# https://github.com/llvm/llvm-project/issues/55924
common --enable_bzlmod=false --enable_workspace

# TODO: Remove lit test reliance on this
common --legacy_external_runfiles

# Prevent invalid caching if input files are modified during a build.
build --experimental_guard_against_concurrent_changes

# Automatically enable --config=(linux|macos|windows) based on the host
build --enable_platform_specific_config

# In opt mode, bazel by default builds both PIC and non-PIC object files for
# tests vs binaries. We don't need this feature and it slows down opt builds
# considerably.
# TODO: Remove platform specifics we're on bazel 7.x https://github.com/bazelbuild/bazel/issues/12439
# Apple platforms always enable pic so this flag is unnecessary anyways
build:linux --force_pic
build:windows --force_pic

# Shared objects take up more space. With fast linkers and binaries that aren't
# super large, the benefits of shared objects are minimal.
build --dynamic_mode=off

# Rely on compiler flags to compile with debug info/strip rather than stripping
# based on compilation_mode.
build --strip=never

# Add layering check to all projects.
build --features=layering_check

# Opt out of legacy lax behavior implicitly exporting files that are rule inputs
# with default visibility.
# See: https://bazel.build/reference/be/functions#exports_files
build --incompatible_no_implicit_file_export

# Enable so downstream users can flip this flag globally, this should
# eventually become the default
common --incompatible_disallow_empty_glob

# TODO: Remove once we move to bazel 7.x
build --experimental_cc_shared_library

# Disabling runfiles links drastically increases performance in slow disk IO
# situations Do not build runfile trees by default. If an execution strategy
# relies on runfile symlink tree, the tree is created on-demand. See:
# https://github.com/bazelbuild/bazel/issues/6627 and
# https://github.com/bazelbuild/bazel/commit/03246077f948f2790a83520e7dccc2625650e6df
build --build_runfile_links=false

###############################################################################
# Options to select different strategies for linking potential dependent
# libraries. The default leaves it disabled.
###############################################################################

build:zlib_external --repo_env=BAZEL_LLVM_ZLIB_STRATEGY=external
build:zlib_system --repo_env=BAZEL_LLVM_ZLIB_STRATEGY=system

###############################################################################
# Options for "generic_clang" builds: these options should generally apply to
# builds using a Clang-based compiler, and default to the `clang` executable on
# the `PATH`. While these are provided for convenience and may serve as a
# reference, it would be preferable for users to configure an explicit C++
# toolchain instead of relying on `.bazelrc` files.
###############################################################################

# Set the default compiler to the `clang` binary on the `PATH`.
build:generic_clang --repo_env=CC=clang

# C++17 standard version is required.
build:generic_clang --cxxopt=-std=c++17 --host_cxxopt=-std=c++17

# Use `-Wall` for Clang.
build:generic_clang --copt=-Wall --host_copt=-Wall

# The Clang available on MacOS has a warning that isn't clean on MLIR code. The
# warning doesn't show up with more recent Clangs, so just disable for now.
build:generic_clang --cxxopt=-Wno-range-loop-analysis --host_cxxopt=-Wno-range-loop-analysis

# Build errors are not a helpful way to enforce deprecation in-repo and it is
# not the point of the Bazel build to catch usage of deprecated APIs.
build:generic_clang --copt=-Wno-deprecated --host_copt=-Wno-deprecated

# lld links faster than other linkers. Assume that anybody using clang also has
# lld available.
build:generic_clang --linkopt=-fuse-ld=lld --host_linkopt=-fuse-ld=lld

###############################################################################
# Options for "generic_gcc" builds: these options should generally apply to
# builds using a GCC-based compiler, and default to the `gcc` executable on
# the `PATH`. While these are provided for convenience and may serve as a
# reference, it would be preferable for users to configure an explicit C++
# toolchain instead of relying on `.bazelrc` files.
###############################################################################

# Set the default compiler to the `gcc` binary on the `PATH`.
build:generic_gcc --repo_env=CC=gcc

# C++17 standard version is required.
build:generic_gcc --cxxopt=-std=c++17 --host_cxxopt=-std=c++17

# Build errors are not a helpful way to enforce deprecation in-repo and it is
# not the point of the Bazel build to catch usage of deprecated APIs.
build:generic_gcc --copt=-Wno-deprecated --host_copt=-Wno-deprecated

# Disable GCC warnings that are noisy and/or false positives on LLVM code.
# These need to be global as some code triggering these is in header files.
build:generic_gcc --copt=-Wno-unused-parameter --host_copt=-Wno-unused-parameter
build:generic_gcc --copt=-Wno-comment --host_copt=-Wno-comment
build:generic_gcc --cxxopt=-Wno-class-memaccess --host_cxxopt=-Wno-class-memaccess
build:generic_gcc --copt=-Wno-maybe-uninitialized --host_copt=-Wno-maybe-uninitialized
build:generic_gcc --copt=-Wno-misleading-indentation --host_copt=-Wno-misleading-indentation

###############################################################################
# Generic Windows flags common to both MSVC and Clang.
###############################################################################

# C++17 standard version is required.
build:windows --cxxopt=/std:c++17 --host_cxxopt=/std:c++17

# Other generic dialect flags.
build:windows --copt=/Zc:strictStrings --host_copt=/Zc:strictStrings
build:windows --copt=/Oi --host_copt=/Oi
build:windows --cxxopt=/Zc:rvalueCast --host_cxxopt=/Zc:rvalueCast

# Use the more flexible bigobj format for C++ files that have lots of symbols.
build:windows --cxxopt=/bigobj --host_cxxopt=/bigobj

###############################################################################
# Windows specific flags for building with MSVC.
###############################################################################

build:msvc --config=windows

build:msvc --copt=/WX --host_copt=/WX    # Treat warnings as errors...
# ...but disable the ones that are violated
build:msvc --copt=/wd4141 --host_copt=/wd4141 # inline used more than once
build:msvc --copt=/wd4244 --host_copt=/wd4244 # conversion type -> type
build:msvc --copt=/wd4267 --host_copt=/wd4267 # conversion size_t -> type
build:msvc --copt=/wd4273 --host_copt=/wd4273 # multiple definitions with different dllimport
build:msvc --copt=/wd4319 --host_copt=/wd4319 # zero-extending after complement
build:msvc --copt=/wd4624 --host_copt=/wd4624 # destructor was implicitly defined as deleted
build:msvc --copt=/wd4804 --host_copt=/wd4804 # comparisons between bool and int
build:msvc --copt=/wd4805 --host_copt=/wd4805 # comparisons between bool and int

build:msvc --linkopt=/WX --host_linkopt=/WX # Treat warnings as errors...
# ...but disable the ones that are violated.
build:msvc --linkopt=/IGNORE:4001 --host_linkopt=/IGNORE:4001 # no object files

###############################################################################
# Options for Windows `clang-cl` builds.
###############################################################################

# We just start with the baseline Windows config as `clang-cl` doesn't accept
# some of the generic Clang flags.
build:clang-cl --config=windows

# Switch from MSVC to the `clang-cl` compiler.
build:clang-cl --compiler=clang-cl

# Use Clang's internal warning flags instead of the ones that sometimes map
# through to MSVC's flags.
build:clang-cl --copt=/clang:-Wall --host_copt=/clang:-Wall
build:clang-cl --copt=/clang:-Werror --host_copt=/clang:-Werror

# This doesn't appear to be enforced by any upstream bot.
build:clang-cl --copt=/clang:-Wno-unused --host_copt=/clang:-Wno-unused

# There appears to be an unused constant in GoogleTest on Windows.
build:clang-cl --copt=/clang:-Wno-unused-const-variable --host_copt=/clang:-Wno-unused-const-variable

# Disable some warnings hit even with `clang-cl` in Clang's own code.
build:clang-cl --copt=/clang:-Wno-inconsistent-dllimport --host_copt=/clang:-Wno-inconsistent-dllimport
build:clang-cl --cxxopt=/clang:-Wno-c++11-narrowing --host_cxxopt=/clang:-Wno-c++11-narrowing

###############################################################################
# Options for continuous integration.
###############################################################################

# -O1 tries to provide a reasonable tradeoff between compile times and runtime
# performance. However, if we start running more tests (e.g. all of
# check-clang) we may want more optimizations.
# Note for anybody considering using --compilation_mode=opt in CI, it builds
# most files twice, one PIC version for shared libraries in tests, and one
# non-PIC version for binaries.
build:ci --copt=-O1

# Use clang.
build:ci --config=generic_clang

# Speedup bazel using a ramdisk.
build:ci --sandbox_base=/dev/shm

# Use system's mpfr and pfm instead of building it from source.
# This is non hermetic but helps with compile time.
build:ci --@llvm-project//libc:mpfr=system
build:ci --@llvm-project//llvm:pfm=system

# Don't build/test targets tagged with "nobuildkite".
build:ci --build_tag_filters=-nobuildkite
build:ci --test_tag_filters=-nobuildkite

# Show as many errors as possible.
build:ci --keep_going

# Show test errors.
build:ci --test_output=errors

# Only show failing tests to reduce output
build:ci --test_summary=terse

# Attempt to work around intermittent issue while trying to fetch remote blob.
# See e.g. https://github.com/bazelbuild/bazel/issues/18694.
build:ci --remote_default_exec_properties=cache-silo-key=CleverPeafowl

###############################################################################

# The user.bazelrc file is not checked in but available for local mods.
# Always keep this at the end of the file so that user flags override.
try-import %workspace%/user.bazelrc