anchor.diff:      rustc
       cargo
       vala
  +    rustPlatform.cargoSetupHook
  +  ] ++ lib.optionals withIntrospection [
       gobject-introspection
     ] ++ lib.optionals stdenv.isDarwin [
       ApplicationServices
  
positive.code:     bzip2
      pango
      libintl
      gobject-introspection
    ] ++ lib.optionals stdenv.isDarwin [
      libobjc
  
negative.code:   ];
  
    configureFlags = [
      (lib.enableFeature withIntrospection "introspection")
  
      # Vapi does not build on MacOS.
      # https://github.com/NixOS/nixpkgs/pull/117081#issuecomment-827782004
      (lib.enableFeature (withIntrospection && !stdenv.isDarwin) "vala")
  
      "--enable-installed-tests"
      "--enable-always-build-tests"
    ] ++ lib.optional stdenv.isDarwin "--disable-Bsymbolic";
  