anchor.diff:    src = fetchurl {
       url = "https://github.com/ivmai/bdwgc/releases/download/v${version}/gc-${version}.tar.gz";
       # We need the multihash because they delete old releases
  -    multihash = "QmQk6ZAat55XZWmDAekm9yNazs7unB68ocjWUA7VwKqHzE";
  -    sha256 = "bd112005563d787675163b5afff02c364fc8deb13a99c03f4e80fdf6608ad41e";
  +    multihash = "QmZ2oL3LwQB7FixEAzqZkSRRsdVV4cMFxGfhRY4jhms9Y1";
  +    sha256 = "b94c1f2535f98354811ee644dccab6e84a0cf73e477ca03fb5a3758fb1fecd1c";
     };
   
     buildInputs = [
  
positive.code:     "--enable-large-config"
    ];
  
    meta = with stdenv.lib; {
      description = "The Boehm-Demers-Weiser conservative garbage collector for C and C++";
      homepage = http://hboehm.info/gc/;
      license = licenses.free;
  
negative.code: { stdenv
  , fetchurl
  , lib
  
  , libatomic_ops
  }:
  
  let
    version = "7.6.4";
  in
  stdenv.mkDerivation rec {
    name = "boehm-gc-${version}";
  