anchor.diff:      (fetchFromGitHub {
         owner  = "berkeley-abc";
         repo   = "abc";
  -      rev    = "3709744c60696c5e3f4cc123939921ce8107fe04";
  -      sha256 = "18a9cjng3qfalq8m9az5ck1y5h4l2pf9ycrvkzs9hn82b1j7vrax";
  +      rev    = "5776ad07e7247993976bffed4802a5737c456782";
  +      sha256 = "1la4idmssg44rp6hd63sd5vybvs3vr14yzvwcg03ls37p39cslnl";
         name   = "yosys-abc";
       })
     ];
  
positive.code: 
    enableParallelBuilding = true;
    nativeBuildInputs = [ pkgconfig ];
    buildInputs = [ tcl readline libffi python3 bison flex protobuf ];
  
    makeFlags = [ "ENABLE_PROTOBUF=1" ];
  
  
negative.code: { stdenv, fetchFromGitHub
  , pkgconfig, bison, flex
  , tcl, readline, libffi, python3
  , protobuf, zlib
  }:
  
  with builtins;
  
  stdenv.mkDerivation rec {
    pname = "yosys";
    version = "2019.08.13";
  
    srcs = [
      (fetchFromGitHub {
        owner  = "yosyshq";
        repo   = "yosys";
        rev    = "19d6b8846f55b4c7be705619f753bec86deadac8";
        sha256 = "185sbkxajx3k9j03n0cxq2qvzwfwdbcxp19h8vnk7ghd5y9gp602";
        name   = "yosys";
      })
  
  