anchor.diff:      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
  +      ${stdenv.lib.optionalString enableShared "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
  +      ${stdenv.lib.optionalString enableShared "ln -s libc++abi.so.1.0 $out/lib/libc++abi.so"}
  +      ${stdenv.lib.optionalString enableShared "ln -s libc++abi.so.1.0 $out/lib/libc++abi.so.1"}
       '';
   
     meta = {
  
positive.code:   postUnpack = ''
      unpackFile ${libcxx.src}
      unpackFile ${llvm.src}
      export cmakeFlags="-DLLVM_PATH=$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}
    '';
  
    installPhase = if stdenv.isDarwin
      then ''
  
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";
  