anchor.diff:      (fetchFromGitHub {
         owner  = "berkeley-abc";
         repo   = "abc";
  -      rev    = "f23ea8e33f6d5cc54f58bec6d9200483e5d8c704";
  -      sha256 = "1xwmq3k5hfavdrs7zbqjxh35kr2pis4i6hhzrq7qzyzs0az0hls9";
  +      rev    = "ae6716b064c842f45109a88e84dca71fe4cc311f";
  +      sha256 = "0g39k16dmrl6q73q39yr5yd9r4rcliz5zxzbnwzh29z9xwi6ipw8";
         name   = "yosys-abc";
       })
     ];
  
positive.code:     make config-${if stdenv.cc.isClang or false then "clang" else "gcc"}
      echo 'ABCREV := default' >> Makefile.conf
      makeFlags="PREFIX=$out $makeFlags"
    '';
  
    meta = {
  
negative.code: 
    enableParallelBuilding = true;
    nativeBuildInputs = [ pkgconfig ];
    buildInputs = [ tcl readline libffi python3 bison flex protobuf ];
  
    makeFlags = [ "ENABLE_PROTOBUF=1" ];
  
    patchPhase = ''
      substituteInPlace ../yosys-abc/Makefile \
  