Language/Types/Function_Types/subtype_named_args_t07.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 The function type (T1, ... Tn, {Tx1 x1, ..., Txk xk}) -> T is a
/// subtype of the function type (S1, ..., Sn, {Sy1 y1, ..., Sym ym }) -> S, if
/// all of the following conditions are met:
/// 1. Either
///    • S is void, Or
///    • T ⇐⇒ S.
/// 2. ∀i ∈ 1..n, Ti ⇐⇒ Si .
/// 3. k ≥ m and yi ∈ {x1 , ..., xk }, i ∈ 1..m.
/// 4. For all yi ∈ {y1 , ..., ym }, yi = xj ⇒ Tj ⇐⇒ Si.
/// @description Checks that function type t1 is not a subtype of function type
/// t2 if its named optional parameters are a smaller subset of t2's.
/// @author rodionov

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

typedef t1({int x});
typedef t2({int x, int y});
typedef t3({int x, int y, int z});

main() {
  Expect.isFalse(() {} is t1);

  Expect.isFalse(({int x = 42}) {} is t2);
  Expect.isFalse(({var x}) {} is t2);

  Expect.isFalse(({int x = 42, int y = 42}) {} is t3);
  Expect.isFalse(({var x, var y}) {} is t3);
}