Unverified Commit 76a8ffa6 authored by Randy Eckenrode's avatar Randy Eckenrode
Browse files

cc-wrapper: use `-cxx-isystem` instead of `-isystem` on Clang 

This allows Clang to always look for the libc++ headers when compling
C++ code (regardless of whether it is invoked with `clang` or `clang++`
while not exposing the headers when compiling plain C code.

See https://releases.llvm.org/21.1.0/tools/clang/docs/ClangCommandLineReference.html#cmdoption-clang-cxx-isystem-directory
parent bd0dd33d

pkgs/build-support/cc-wrapper/default.nix

+3 −3
Original line number Diff line number Diff line
@@ -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++