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cc-wrapper: always include libc++ in the search path #445095

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Merged
reckenrode merged 2 commits into from
Oct 9, 2025
Merged

cc-wrapper: always include libc++ in the search path #445095

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bd0dd33
cc-wrapper: always include libc++ in the search path
reckenrode Apr 21, 2025
76a8ffa
cc-wrapper: use `-cxx-isystem` instead of `-isystem` on Clang
reckenrode Sep 22, 2025
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9 changes: 9 additions & 0 deletions pkgs/build-support/cc-wrapper/cc-wrapper.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -140,6 +140,15 @@ if [ "$NIX_ENFORCE_NO_NATIVE_@suffixSalt@" = 1 ]; then
params=(${kept+"${kept[@]}"})
fi

# Some build systems such as Bazel and SwiftPM use `clang` instead of `clang++`,
# which will find the libc++ headers in the sysroot for C++ files.
if [[ "$isCxx" = 0 && "@isClang@" ]]; then
# This duplicates the behavior of a native toolchain, which can find the
# libc++ headers but requires `-lc++` to be specified explicitly when linking.
isCxx=1
cxxLibrary=0
fi

if [[ "$isCxx" = 1 ]]; then
if [[ "$cxxInclude" = 1 ]]; then
#
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6 changes: 3 additions & 3 deletions pkgs/build-support/cc-wrapper/default.nix
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Expand Up @@ -741,14 +741,14 @@ stdenvNoCC.mkDerivation {
# https://github.com/NixOS/nixpkgs/pull/209870#issuecomment-1500550903)
+ optionalString (libcxx == null && isClang && (useGccForLibs && gccForLibs.langCC or false)) ''
for dir in ${gccForLibs}/include/c++/*; do
include -isystem "$dir" >> $out/nix-support/libcxx-cxxflags
include -cxx-isystem "$dir" >> $out/nix-support/libcxx-cxxflags
done
for dir in ${gccForLibs}/include/c++/*/${targetPlatform.config}; do
include -isystem "$dir" >> $out/nix-support/libcxx-cxxflags
include -cxx-isystem "$dir" >> $out/nix-support/libcxx-cxxflags
done
''
+ optionalString (libcxx.isLLVM or false) ''
include -isystem "${getDev libcxx}/include/c++/v1" >> $out/nix-support/libcxx-cxxflags
include -cxx-isystem "${getDev libcxx}/include/c++/v1" >> $out/nix-support/libcxx-cxxflags
echo "-stdlib=libc++" >> $out/nix-support/libcxx-ldflags
''
# GCC NG friendly libc++
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