anchor.diff:    ] ++ optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
         "--cross-prefix=${stdenv.cc.targetPrefix}"
         "--enable-cross-compile"
  -  ] ++ optional stdenv.cc.isClang "--cc=clang";
  +  ] ++ optional stdenv.cc.isClang "--cc=clang");
   
     nativeBuildInputs = [ addOpenGLRunpath perl pkgconfig texinfo yasm ];
   
  
positive.code: 
  let
    inherit (stdenv) isDarwin isFreeBSD isLinux isAarch32;
    inherit (stdenv.lib) optional optionals optionalString enableFeature;
  
    cmpVer = builtins.compareVersions;
    reqMin = requiredVersion: (cmpVer requiredVersion branch != 1);
  
negative.code:   setOutputFlags = false; # doesn't accept all and stores configureFlags in libs!
  
    configurePlatforms = [];
    configureFlags = filter (v: v != null) ([
        "--arch=${stdenv.hostPlatform.parsed.cpu.name}"
        "--target_os=${stdenv.hostPlatform.parsed.kernel.name}"
      # License
  