anchor.diff:  
     src = fetchgit {
       url = https://github.com/rust-lang/rust;
  -    rev = "3a325c666d2cb7e297bf3057ff2442f96a79428b";
  -    sha256 = "0a0byglfaf0wfsnlm53vng1gqkkz4i29zphdwqg93v26mciqqc61";
  +    rev = "34d680009205de2302b902d8f9f5f7ae7a042f1a";
  +    sha256 = "0qj9b8yzvks42kqr5kxmrq9jwsaj1hmnb156sqjcfywcsdvkzjfw";
     };
   
     # We need rust to build rust. If we don't provide it, configure will try to download it.
  
positive.code:       --subst-var-by "ccPath" "${stdenv.gcc}/bin/cc"
      substituteInPlace src/librustc_back/archive.rs \
        --subst-var-by "arPath" "${stdenv.gcc.binutils}/bin/ar"
    '';
  
    buildInputs = [ which file perl curl python27 makeWrapper git valgrind ];
  
    enableParallelBuilding = false; # disabled due to rust-lang/rust#16305
  
  
negative.code: 
  */
  
  with ((import ./common.nix) {inherit stdenv; version = "0.13.0-pre-2600-g34d6800";});
  
  let snapshot = if stdenv.system == "i686-linux"
        then "3daf531aed03f5769402f2fef852377e2838db98"
        else if stdenv.system == "x86_64-linux"
        then "4f3c8b092dd4fe159d6f25a217cf62e0e899b365"
        else if stdenv.system == "i686-darwin"
        then "2a3e647b9c400505bd49cfe56091e866c83574ca"
        else if stdenv.system == "x86_64-darwin"
        then "5e730efc34d79a33f464a87686c10eace0760a2e"
        else abort "no-snapshot for platform ${stdenv.system}";
      snapshotDate = "2014-12-20";
      snapshotRev = "8443b09";
      snapshotName = "rust-stage0-${snapshotDate}-${snapshotRev}-${platform}-${snapshot}.tar.bz2";
  
  in stdenv.mkDerivation {
  