anchor.diff:  in
   with stdenv; mkDerivation rec {
     pname = "nextpnr";
  -  version = "2019.08.31";
  +  version = "2019.09.28";
   
     src = fetchFromGitHub {
       owner  = "yosyshq";
       repo   = "nextpnr";
  -    rev    = "c0b7379e8672b6263152d5e340e62f22179fdc8b";
  -    sha256 = "174n962xiwyzy53cn192h9rq95h951k3xy6bs43p5ya592ai5mjh";
  +    rev    = "7cd1e0495122847611b17a8d1f007d97a05b288c";
  +    sha256 = "13y739l92plb22g73jf35pyh3y94b2vq0i65r9c31r2rb7fw4bbl";
  +    fetchSubmodules = true;
     };
   
     nativeBuildInputs
  
positive.code:       "-DUSE_OPENMP=ON"
        # warning: high RAM usage
        "-DSERIALIZE_CHIPDB=OFF"
        # use PyPy for icestorm if enabled
        "-DPYTHON_EXECUTABLE=${icestorm.pythonInterp}"
      ]
      ++ (lib.optional (!enableGui) "-DBUILD_GUI=OFF")
      ++ (lib.optional (enableGui && stdenv.isDarwin)
  
negative.code:   patchPhase = with builtins; ''
      substituteInPlace ./CMakeLists.txt \
        --replace 'git log -1 --format=%h' 'echo ${substring 0 11 src.rev}'
  
      # use PyPy for icestorm if enabled
      substituteInPlace ./ice40/family.cmake \
        --replace ''\'''${PYTHON_EXECUTABLE}' '${icestorm.pythonInterp}'
    '';
  
  
  