anchor.diff:    enableParallelBuilding = true;
   
     patchPhase = ''
  -    substituteInPlace ./VERSION --replace 3.4 3.5
       substituteInPlace ./configure \
         --replace '{toolprefix}gcc' '{toolprefix}cc'
     '';
  
positive.code: { stdenv, lib, fetchurl, fetchpatch, makeWrapper
  , coq, ocamlPackages, coq2html
  , tools ? stdenv.cc
  }:
  
negative.code:   name    = "compcert-${version}";
    version = "3.5";
  
    src = fetchFromGitHub {
      owner = "AbsInt";
      repo = "CompCert";
      rev = "v${version}";
      sha256 = "1g8067a5x3vd0l47d04gjvy5yx49nghh55am5d1fbrjirfsnsz8j";
    };
  
    nativeBuildInputs = [ makeWrapper ];
  