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disable module for all stdlib #544

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Merged
merged 1 commit into from
Sep 8, 2025
Merged

disable module for all stdlib #544

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19 changes: 10 additions & 9 deletions toolchain/cc_toolchain_config.bzl
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Original file line number Diff line number Diff line change
Expand Up @@ -259,15 +259,6 @@ def cc_toolchain_config(
"-std=" + cxx_standard,
"-stdlib=libc++",
]
if major_llvm_version >= 14:
# With C++20, Clang defaults to using C++ rather than Clang modules,
# which breaks Bazel's `use_module_maps` feature, which is used by
# `layering_check`. Since Bazel doesn't support C++ modules yet, it
# is safe to disable them globally until the toolchain shipped by
# Bazel sets this flag on `use_module_maps`.
# https://github.com/llvm/llvm-project/commit/0556138624edf48621dd49a463dbe12e7101f17d
cxx_flags.append("-Xclang")
cxx_flags.append("-fno-cxx-modules")
if use_lld:
# For single-platform builds, we can statically link the bundled
# libraries.
Expand Down Expand Up @@ -343,6 +334,16 @@ def cc_toolchain_config(
else:
fail("Unknown value passed for stdlib: {stdlib}".format(stdlib = stdlib))

if major_llvm_version >= 14:
# With C++20, Clang defaults to using C++ rather than Clang modules,
# which breaks Bazel's `use_module_maps` feature, which is used by
# `layering_check`. Since Bazel doesn't support C++ modules yet, it
# is safe to disable them globally until the toolchain shipped by
# Bazel sets this flag on `use_module_maps`.
# https://github.com/llvm/llvm-project/commit/0556138624edf48621dd49a463dbe12e7101f17d
cxx_flags.append("-Xclang")
cxx_flags.append("-fno-cxx-modules")

opt_link_flags = ["-Wl,--gc-sections"] if target_os == "linux" else []

# Coverage flags:
Expand Down