anchor.diff:  # ultimately less confusing than using dates.
   
   stdenv.mkDerivation rec {
  +  inherit plugins;
  +
     pname   = "yosys";
     version = "0.9+3830";
   
  
positive.code: , fetchFromGitHub
  , flex
  , libffi
  , pkgconfig
  , protobuf
  , python3
  , readline
  , tcl
  , verilog
  , zlib
  }:
  
  # NOTE: as of late 2020, yosys has switched to an automation robot that
  
negative.code:   };
  
    enableParallelBuilding = true;
    nativeBuildInputs = [ pkg-config protobuf flex bison python3 ];
    buildInputs = [ tcl readline libffi python3 protobuf zlib ];
  
    makeFlags = [ "ENABLE_PROTOBUF=1" "PREFIX=${placeholder "out"}"];
  
    patchPhase = ''
      substituteInPlace ./Makefile \
        --replace 'echo UNKNOWN' 'echo ${builtins.substring 0 10 src.rev}'
      chmod +x ./misc/yosys-config.in
      patchShebangs ./misc/yosys-config.in
      patchShebangs tests
    '';
  
  