anchor.diff:    pname = "gupnp";
     version = "1.4.0";
   
  -  outputs = [ "out" "dev" "devdoc" ];
  +  outputs = [ "out" "dev" ]
  +    ++ lib.optionals (stdenv.buildPlatform == stdenv.hostPlatform) [ "devdoc" ];
   
     src = fetchurl {
       url = "mirror://gnome/sources/gupnp/${lib.versions.majorMinor version}/${pname}-${version}.tar.xz";
  
positive.code:   patches = [
      # Bring .pc file in line with our patched pkg-config.
      ./0001-pkg-config-Declare-header-dependencies-as-public.patch
    ];
  
    nativeBuildInputs = [
  
negative.code:   ];
  
    mesonFlags = [
      "-Dgtk_doc=${lib.boolToString (stdenv.buildPlatform == stdenv.hostPlatform)}"
      "-Dintrospection=${lib.boolToString (stdenv.buildPlatform == stdenv.hostPlatform)}"
    ];
  
    doCheck = true;
  