Language/Types/Function_Types/subtype_named_args_t06.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 they have different number of required parameters.
/// @author rodionov

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

typedef t1(int x);
typedef t2(int x, int y);

main() {
  Expect.isFalse(() {} is t1);
  Expect.isFalse((int x, var y) {} is t1);
  Expect.isFalse((int x, int y) {} is t1);
  Expect.isFalse(({required int x}) {} is t1);
  Expect.isFalse(({required var x}) {} is t1);

  Expect.isFalse(() {} is t2);
  Expect.isFalse((int x) {} is t2);
  Expect.isFalse((int y) {} is t2);
  Expect.isFalse((int x, {required int y}) {} is t2);
  Expect.isFalse(({required int x, required int y}) {} is t2);
  Expect.isFalse((int x, int y, int z) {} is t2);
}