anchor.diff:  let
     generic = { version, sha256 }:
       stdenv.mkDerivation {
  -      name = "spdlog-${version}";
  +      pname = "spdlog";
         inherit version;
   
         src = fetchFromGitHub {
  
positive.code: 
        nativeBuildInputs = [ cmake ];
  
        cmakeFlags = [ "-DSPDLOG_BUILD_EXAMPLES=OFF" "-DSPDLOG_BUILD_BENCH=OFF" ];
  
        outputs = [ "out" "doc" ];
  
  
negative.code:       '';
  
        meta = with stdenv.lib; {
          description    = "Very fast, header only, C++ logging library";
          homepage       = "https://github.com/gabime/spdlog";
          license        = licenses.mit;
          maintainers    = with maintainers; [ obadz ];
          platforms      = platforms.all;
  