LanguageFeatures/Abstract-external-fields/static_analysis_abstract_A05_t03.dart

// Copyright (c) 2020, 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.

/**
 * @assertion An abstract instance variable declaration D is treated as an
 * abstract getter declaration and possibly an abstract setter declaration. The
 * setter is included if and only if D is non-final. The return type of the
 * getter and the parameter type of the setter, if present, is the type of D
 * (which may be declared explicitly, obtained by override inference, or
 * defaulted to dynamic). The parameter of the setter, if present, has the
 * modifier covariant if and only if D has the modifier covariant
 *
 * @description Checks that declaration
 *   abstract covariant num cn;
 * desugared as
 *   num get cn;
 *   void set cn(covariant num _);
 * @author sgrekhov@unipro.ru
 */
import "../../Utils/expect.dart";

abstract class A {
  abstract covariant num cn;
}

class C1 extends A {
  num get cn => 3.14;
  void set cn(num _) {}
}

class C2 extends C1 {
  // Without covariant keyword in class A overrides below are not valid
  int get cn => 42;
  void set cn(int _) {}
}

main() {
  C2 c2 = new C2();
  Expect.equals(42, c2.cn);
}