pkg/front_end/testcases/extensions/builtin_identifiers.dart

// Copyright (c) 2019, 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
extension mixin on int {}

extension extension on int {}

extension as on int {}

void main() {}