Language/Types/Function_Types/subtype_optional_args_t05.dart

// Copyright (c) 2011, 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 A function type (T1,...Tk,[Tk+1,...,Tn+m]) -> T is a subtype of
 * the function type (S1,...,Sk+j,[Sk+j+1,...,Sn]) -> S, if all of the following
 * conditions are met:
 * 1. Either
 *    • S is void, or
 *    • T <=> S.
 * 2. ∀i ∈ 1..n, Ti ⇐⇒ Si.
 * @description Checks that function type t1 is not a subtype of function type
 * t2 if the declared type of an positional optional parameter of t1 is not
 * assignable to a corresponding parameter of t2 (both t1 and t2 have a single
 * positional optional parameter).
 * @author iefremov
 */
import "../../../Utils/expect.dart";

class A {}
class B {}

typedef t1([int p]);
typedef t3([A? p]);
typedef t4([List<A> p]);
typedef t5([t1? p]);

main() {
  Expect.isFalse(([double p = 3.14]) {} is t1);
  Expect.isFalse(([bool p = false]) {} is t1);
  Expect.isFalse(([A? p]) {} is t1);
  Expect.isFalse(([List<int> p = const [3, 1, 4]]) {} is t1);
  Expect.isFalse(([t3? p]) {} is t1);

  Expect.isFalse(([double p = 0]) {} is t3);
  Expect.isFalse(([bool p = true]) {} is t3);
  Expect.isFalse(([List<int> p = const []]) {} is t3);
  Expect.isFalse(([t3? p]) {} is t3);
  Expect.isFalse(([B? p]) {} is t3);

  Expect.isFalse(([double p = 0]) {} is t4);
  Expect.isFalse(([bool p = false]) {} is t4);
  Expect.isFalse(([A? p]) {} is t4);
  Expect.isFalse(([List<int> p = const [3, 1, 4]]) {} is t4);
  Expect.isFalse(([List<B>? p]) {} is t4);
  Expect.isFalse(([t3? p]) {} is t4);

  Expect.isFalse(([double p = 3.14]) {} is t5);
  Expect.isFalse(([bool p = false]) {} is t5);
  Expect.isFalse(([A? p]) {} is t5);
  Expect.isFalse(([List<int> p = const [1, 2, 3]]) {} is t5);
  Expect.isFalse(([t3? p]) {} is t5);
  Expect.isFalse(([t4? p]) {} is t5);
  Expect.isFalse(([t5? p]) {} is t5);
}