anchor.diff:    postUnpack = ''
       unpackFile ${libcxx.src}
       unpackFile ${llvm.src}
  -    export cmakeFlags="-DLLVM_PATH=$PWD/$(ls -d llvm-*) -DLIBCXXABI_LIBCXX_PATH=$PWD/$(ls -d libcxx-*)"
  +    cmakeFlagsArray=($cmakeFlagsArray -DLLVM_PATH=$PWD/$(ls -d llvm-*) -DLIBCXXABI_LIBCXX_PATH=$PWD/$(ls -d libcxx-*) )
     '' + stdenv.lib.optionalString stdenv.isDarwin ''
       export TRIPLE=x86_64-apple-darwin
     '' + stdenv.lib.optionalString stdenv.hostPlatform.isMusl ''
       patch -p1 -d $(ls -d libcxx-*) -i ${../libcxx-0001-musl-hacks.patch}
     '';
  +
  +  cmakeFlags = stdenv.lib.optional (!enableShared) "-DLIBCXXABI_ENABLE_SHARED=OFF";
   
     installPhase = if stdenv.isDarwin
       then ''
  
positive.code:     else ''
        install -d -m 755 $out/include $out/lib
        install -m 644 lib/libc++abi.a $out/lib
        install -m 644 lib/libc++abi.so.1.0 $out/lib
        install -m 644 ../include/cxxabi.h $out/include
        ln -s libc++abi.so.1.0 $out/lib/libc++abi.so
        ln -s libc++abi.so.1.0 $out/lib/libc++abi.so.1
      '';
  
    meta = {
  
negative.code: { stdenv, cmake, fetch, libcxx, llvm, version
    # on musl the shared objects don't build
  , enableShared ? ! stdenv.hostPlatform.isMusl }:
  
  stdenv.mkDerivation {
    pname = "libc++abi";
  