anchor.diff: -{ stdenv, fetchurl, pkgconfig
  +{ lib, stdenv, fetchurl, pkgconfig
   , libffi, docbook_xsl, doxygen, graphviz, libxslt, xmlto
   , expat ? null # Build wayland-scanner (currently cannot be disabled as of 1.7.0)
   }:
  
positive.code:   meta = {
      description = "Reference implementation of the wayland protocol";
      homepage    = http://wayland.freedesktop.org/;
      license     = licenses.mit;
      platforms   = platforms.linux;
      maintainers = with maintainers; [ codyopel wkennington ];
    };
  
    passthru.version = version;
  
negative.code: # Require the optional to be enabled until upstream fixes or removes the configure flag
  assert expat != null;
  
  stdenv.mkDerivation rec {
    name = "wayland-${version}";
    version = "1.7.0";
  