anchor.diff:      installPhase = ''
         mkdir -p "$out"
         cp -r bin "$out/bin"
  -    '' + (if stdenv.isLinux then ''
  +    '' + stdenv.lib.optionalString stdenv.isLinux ''
         patchelf --interpreter "${stdenv.glibc}/lib/${stdenv.cc.dynamicLinker}" \
                  --set-rpath "${stdenv.cc.cc}/lib/:${stdenv.cc.cc}/lib64/" \
                  "$out/bin/rustc"
  -    '' else "");
  +    '';
     };
   
     configureFlags = configureFlags
  -                ++ [ "--enable-local-rust" "--local-rust-root=$snapshot" ]
  -                ++ stdenv.lib.optional (stdenv.cc ? clang) "--enable-clang";
  +                ++ [ "--enable-local-rust" "--local-rust-root=$snapshot" "--enable-rpath" ]
  +                ++ stdenv.lib.optional (stdenv.cc.cc ? isClang) "--enable-clang";
   
     inherit patches;
   
  
positive.code:       --replace /bin/echo "${coreutils}/bin/echo"
    '';
  
    buildInputs = [ which file perl curl python27 makeWrapper git valgrind procps ];
  
    enableParallelBuilding = true;
  
  
negative.code:   inherit version;
    inherit meta;
  
    __impureHostDeps = [ "/usr/lib/libedit.3.dylib" ];
  
    src = if isRelease then
        fetchzip {
          url = "http://static.rust-lang.org/dist/rustc-${version}-src.tar.gz";
  