anchor.diff:  , nixosTests
   , gtk3Support ? false
   , gtk3 ? null
  -, qt4 ? null
  -, qt4Support ? false
   , qt5 ? null
   , qt5Support ? false
   , withLibdnssdCompat ? false
   , python ? null
   , withPython ? false
   }:
  -
  -assert qt4Support -> qt4 != null;
   
   stdenv.mkDerivation rec {
     pname = "avahi${lib.optionalString withLibdnssdCompat "-compat"}";
  
positive.code:     XMLParser
    ]) ++ lib.optionals gtk3Support [
      gtk3
    ] ++ lib.optionals qt4Support [
      qt4
    ] ++ lib.optionals qt5Support [
      qt5
    ];
  
negative.code:     # Use non-deprecated path https://github.com/lathiat/avahi/pull/376
      "--with-dbus-sys=${placeholder "out"}/share/dbus-1/system.d"
      (lib.enableFeature gtk3Support "gtk3")
      (lib.enableFeature qt5Support "qt5")
      (lib.enableFeature withPython "python")
      "--localstatedir=/var"
  