LanguageFeatures/Set-literals/type_inference_A02_t03.dart

// Copyright (c) 2019, 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 In a setOrMapLiteral collection, the inferred type of an element
/// is a set element type T, a pair of a key type K and a value type V, or both.
/// It is computed relative to a context type P:
/// ...
/// If collection is unambiguously a map literal then P is Map<Pk, Pv> where Pk
/// and Pv are determined by downwards inference, and may be ? if the downwards
/// context does not constrain one or both.
///
/// @description Checks that if collection is unambiguously a map literal then P
/// is Map<Pk, Pv> where Pk and Pv are determined by downwards inference, and may
/// be ? if the downwards context does not constrain one or both.
/// @author sgrekhov@unipro.ru

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

void test<X extends num, Y extends Object>(X x, Y y) {
  var m1 = {x: y};
  var m2 = <X, Y>{};
  Expect.isTrue(m1 is Map<int, double>);
  Expect.isTrue(m2 is Map<num, Object>);
  Expect.runtimeIsType<Map<int, double>>(m1);
  Expect.runtimeIsType<Map<num, Object>>(m2);
}

main() {
  test(3, 3.1415926);
}