// 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

class A {}

class B extends A {
  B operator +(int i) => this;
}

class C {
  B operator [](int i) => new B();

  void operator []=(int i, A value) {}
}

main() {
  new C()[0] += 1;
}