pkg/front_end/testcases/general/metadata_enum.dart

// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
// @dart=2.9
const a = null;

@a
enum E { E1, E2, E3 }

main() {}