anchor.diff:  , pdfSupport ? true
   , pngSupport ? true
   , xcbSupport ? false
  +, glSupport ? false
   , gobjectSupport ? true, glib
   , stdenv, fetchurl, pkgconfig, x11, fontconfig, freetype, xlibs
  -, zlib, libpng, pixman, libxcb ? null, xcbutil ? null
  +, zlib, libpng, pixman, libxcb ? null, xcbutil ? null, mesa ? null
   , gettext, libiconvOrEmpty
   }:
   
   assert postscriptSupport -> zlib != null;
   assert pngSupport -> libpng != null;
   assert xcbSupport -> libxcb != null && xcbutil != null;
  +assert glSupport -> mesa != null;
   
   stdenv.mkDerivation rec {
     name = "cairo-1.12.4";
  
positive.code:   buildInputs =
      [ pkgconfig x11 fontconfig xlibs.libXrender ]
      ++ stdenv.lib.optionals xcbSupport [ libxcb xcbutil ]
  
      # On non-GNU systems we need GNU Gettext for libintl.
      ++ stdenv.lib.optional (!stdenv.isLinux) gettext
  
negative.code:   configureFlags =
      [ "--enable-tee" ]
      ++ stdenv.lib.optional xcbSupport "--enable-xcb"
      ++ stdenv.lib.optional glSupport "--enable-gl"
      ++ stdenv.lib.optional pdfSupport "--enable-pdf";
  
    preConfigure = ''
  