anchor.diff:  */
   
   let
  -  version = "9.1.3";
  +  version = "9.1.5";
     driverLink = "/run/opengl-driver" + stdenv.lib.optionalString stdenv.isi686 "-32";
   in
   stdenv.mkDerivation {
  
positive.code: 
    src = fetchurl {
      url = "ftp://ftp.freedesktop.org/pub/mesa/${version}/MesaLib-${version}.tar.bz2";
      sha256="0rnpaambxv5cd6kbfyvv4b8x2rw1xj13a67xbkzmndfh08iaqpcd";
    };
  
    prePatch = "patchShebangs .";
  
negative.code: , libdrm, xorg, wayland, udev, llvm, libffi
  , libvdpau
  , enableTextureFloats ? false # Texture floats are patented, see docs/patents.txt
  , enableR600LlvmCompiler ? false # current llvm-3.3 + mesa-9.1.5 don't compile this
  , enableExtraFeatures ? false # add ~15 MB to mesa_drivers
  }:
  
  