anchor.diff:      pkg-config
       rustc
       cargo
  +    python3.pkgs.docutils
       vala
       rustPlatform.cargoSetupHook
     ] ++ lib.optionals withIntrospection [
       gobject-introspection
  +    gi-docgen
     ];
   
     buildInputs = [
  
positive.code: , rustc
  , rust
  , cargo
  , gnome
  , vala
  , withIntrospection ? stdenv.hostPlatform == stdenv.buildPlatform
  
negative.code: 
  stdenv.mkDerivation rec {
    pname = "librsvg";
    version = "2.53.1";
  
    outputs = [ "out" "dev" "installedTests" ] ++ lib.optionals withIntrospection [
      "devdoc"
    ];
  
    src = fetchurl {
      url = "mirror://gnome/sources/${pname}/${lib.versions.majorMinor version}/${pname}-${version}.tar.xz";
      sha256 = "uo4EAHR0nzhFRFxWAuCQLzAHoYsHTPDMahDI3cWmUyI=";
    };
  
    cargoVendorDir = "vendor";
  