anchor.diff:      mv $GDK_PIXBUF/loaders.cache.tmp $GDK_PIXBUF/loaders.cache
     '';
   
  -  postFixup = ''
  +  postFixup = lib.optionalString withIntrospection ''
       # Cannot be in postInstall, otherwise _multioutDocs hook in preFixup will move right back.
       moveToOutput "share/doc" "$devdoc"
     '';
  
positive.code:     pkg-config
      rustc
      cargo
      python3.pkgs.docutils
      vala
      rustPlatform.cargoSetupHook
    ] ++ lib.optionals withIntrospection [
  
negative.code: , rust
  , cargo
  , gi-docgen
  , python3Packages
  , gnome
  , vala
  , withIntrospection ? stdenv.hostPlatform == stdenv.buildPlatform
  