anchor.diff:      ++ stdenv.lib.optionals (isDarwin) [
       "-DLLVM_ENABLE_LIBCXX=ON"
       "-DCAN_TARGET_i386=false"
  +  ] ++ stdenv.lib.optionals (buildPlatform != hostPlatform) [
  +    "-DCMAKE_CROSSCOMPILING=True"
  +    "-DLLVM_TABLEGEN=${buildPackages.llvmPackages_39.llvm}/bin/llvm-tblgen"
     ];
   
     postBuild = ''
  
positive.code: , debugVersion ? false
  , enableSharedLibraries ? true
  , darwin
  }:
  
  let
  
negative.code: 
    outputs = [ "out" ] ++ stdenv.lib.optional enableSharedLibraries "lib";
  
    buildInputs = [
      buildPackages.perl
      buildPackages.buildPackages.cmake
      buildPackages.python
      groff
      libxml2
      libffi ]
      ++ stdenv.lib.optionals stdenv.isDarwin [ libcxxabi ];
  
    propagatedBuildInputs = [ ncurses zlib ];
  