anchor.diff:  
   stdenv.mkDerivation rec {
     pname = "libclc";
  -  version = "11.0.1";
  +  version = "12.0.1";
   
     src = fetchFromGitHub {
       owner = "llvm";
       repo = "llvm-project";
       rev = "llvmorg-${version}";
  -    sha256 = "0bxh43hp1vl4axl3s9n2nb2ii8x1cbq98xz9c996f8rl5jy84ags";
  +    sha256 = "08s5w2db9imb2yaqsvxs6pg21csi1cf6wa35rf8x6q07mam7j8qv";
     };
     sourceRoot = "source/libclc";
   
  
positive.code: { lib, stdenv, fetchFromGitHub, ninja, cmake, python3, llvmPackages }:
  
  let
    llvm = llvmPackages.llvm;
  
negative.code:   postPatch = ''
      substituteInPlace CMakeLists.txt \
        --replace 'find_program( LLVM_CLANG clang PATHS ''${LLVM_BINDIR} NO_DEFAULT_PATH )' \
                  'find_program( LLVM_CLANG clang PATHS "${clang-unwrapped}/bin" NO_DEFAULT_PATH )' \
        --replace 'find_program( LLVM_SPIRV llvm-spirv PATHS ''${LLVM_BINDIR} NO_DEFAULT_PATH )' \
                  'find_program( LLVM_SPIRV llvm-spirv PATHS "${spirv-llvm-translator}/bin" NO_DEFAULT_PATH )'
    '';
  
    nativeBuildInputs = [ cmake ninja python3 spirv-llvm-translator ];
    buildInputs = [ llvm clang-unwrapped ];
    strictDeps = true;
    cmakeFlags = [
  