anchor.diff:        python3 = super.python3Minimal;
   
         ninja = super.ninja.override { buildDocs = false; };
  +
  +      llvmPackages_7 = super.llvmPackages_7 // (let
  +        libraries = super.llvmPackages_7.libraries.extend (_: _: {
  +          inherit (llvmPackages_7) compiler-rt;
  +        });
  +      in { inherit libraries; } // libraries);
       };
     in with prevStage; stageFun 1 prevStage {
       extraPreHook = "export NIX_CFLAGS_COMPILE+=\" -F${bootstrapTools}/Library/Frameworks\"";
  
positive.code:         inherit shell;
          inherit (last) stdenvNoCC;
  
          extraPackages = [];
  
          nativeTools  = false;
          nativeLibc   = false;
  
negative.code:     allowedRequisites =
        [ bootstrapTools ] ++
        (with pkgs; [
          xz.bin xz.out libcxx libcxxabi llvmPackages_7.compiler-rt zlib
          libxml2.out curl.out openssl.out libssh2.out nghttp2.lib libkrb5
        ]) ++
        (with pkgs.darwin; [ dyld Libsystem CF ICU locale ]);
  
  