Language/Types/Function_Types/subtype_optional_args_t10.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 even if just one of t1's optional positional parameters has a type that is
/// not mutually assignable with the type of t2's corresponding positional
/// optional parameter.
/// @author iefremov

import "../../../Utils/expect.dart";

class B {}

typedef B func(Object o);
typedef B t1(int i, B b, Map<int, num> m, var x, [var ox, B? ob, List<num>? ol, bool? obool]);

B f1(int i, B b, Map<int, num> m, var x, [var ox, func? ob, List<num>? ol, bool? obool]) => new B();
//                                                ^^^ func <=/=> B
B f2(int i, B b, Map<int, num> m, var x, [var ox, B? ob, List<B>? ol, bool? obool]) => new B();
//                                                          ^^^ B <=/=> num
B f3(num i, B b, Map<int, num> m, var x, [var ox, B? ob, List<num>? ol, int? obool]) => new B();
//                                                                    ^^^ int <=/=> bool

main() {
  Expect.isFalse(f1 is t1);
  Expect.isFalse(f2 is t1);
  Expect.isFalse(f3 is t1);
}