anchor.diff:  
       outputs = [ "out" "lib" "dev" "python" ];
   
  -    # Clang expects to find LLVMgold in its own prefix
       postInstall = ''
  -      if [ -e ${libllvm.lib}/lib/LLVMgold.so ]; then
  -        ln -sv ${libllvm.lib}/lib/LLVMgold.so $lib/lib
  -      fi
  -
         ln -sv $out/bin/clang $out/bin/cpp
   
         # Move libclang to 'lib' output
  
positive.code:       ./purity.patch
        # https://reviews.llvm.org/D51899
        ./gnu-install-dirs.patch
      ];
  
      postPatch = ''
  
negative.code: { lib, stdenv, llvm_meta, src, substituteAll, cmake, libxml2, libllvm, version, python3
  , buildLlvmTools
  , fixDarwinDylibNames
  , enableManpages ? false
  