anchor.diff:      optionalString
       splitString;
   
  -  version = "17.2.6";
  +  version = "17.3.0";
   
     # this is the default search path for DRI drivers
     driverSearchPath = "/run/opengl-driver-${stdenv.targetSystem}";
  
positive.code:     "--${boolEn (buildConfig != "opengl-dummy")}-nine" # Direct3D in Wine
      "--${boolEn (buildConfig != "opengl-dummy")}-xvmc"
      "--${boolEn (buildConfig != "opengl-dummy")}-vdpau"
      "--${boolEn (buildConfig != "opengl-dummy")}-omx"
      "--${boolEn (buildConfig != "opengl-dummy")}-va"
      # TODO: Figure out how to enable opencl without having a
      #       runtime dependency on clang
  
negative.code:         + head (splitString "." version)
          + ".x/${version}/mesa-${version}.tar.xz")
      ];
      multihash = "QmeY8h2gdqj5ZBS4E3JMe6tafnwNivtqoeGJLMkx2Pkg8i";
      hashOutput = false;  # Provided by upstream directly
      sha256 = "29a0a3a6c39990d491a1a58ed5c692e596b3bfc6c01d0b45e0b787116c50c6d9";
    };
  
    nativeBuildInputs = [
      autoreconfHook
      python2Packages.python
    ] ++ optionals (buildConfig != "opengl-dummy") [
      bison
      flex
      gettext
      intltool
      python2Packages.Mako
      xorg.makedepend
    ];
  