anchor.diff:  let
     inherit (localSystem) system platform;
   
  +  bootstrapClangVersion = "7.1.0";
  +
     commonImpureHostDeps = [
       "/bin/sh"
       "/usr/lib/libSystem.B.dylib"
  
positive.code:       python3 = super.python3Minimal;
  
        ninja = super.ninja.override { buildDocs = false; };
      };
    in with prevStage; stageFun 1 prevStage {
      extraPreHook = "export NIX_CFLAGS_COMPILE+=\" -F${bootstrapTools}/Library/Frameworks\"";
  
negative.code:             ln -s ${bootstrapTools}/lib/libc++abi.dylib $out/lib/libc++abi.dylib
            '';
          };
  
          compiler-rt = stdenv.mkDerivation {
            name = "bootstrap-stage0-compiler-rt";
            buildCommand = ''
              mkdir -p $out/lib
              ln -s ${bootstrapTools}/lib/libclang_rt* $out/lib
              ln -s ${bootstrapTools}/lib/darwin       $out/lib/darwin
            '';
          };
        };
      };
  
  