pkg/front_end/testcases/extension_types/issue53539.dart - sdk - Git at Google

 // Copyright (c) 2023, 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.

 extension type ET(int id) {
   void set id(String i) /* Error */ {}
 }
	// Copyright (c) 2023, 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.

	extension type ET(int id) {
	void set id(String i) /* Error */ {}
	}