LanguageFeatures/Set-literals/type_inference_A02_t02.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 test1<X, Y>(X x, Y y) {
  var m = {x: y};
  Expect.isTrue(m is Map<int, double>);
}

void test2<X, Y>(X x, Y y) {
  var m = {x: y};
  Expect.isTrue(m is Map<double, int>);
}

void test3<X, Y>(X x, Y y) {
  var m = {x: y};
  Expect.isTrue(m is Map<num, num>);
}

main() {
  test1(3, 3.1415926);
  test2(3.14, 2);
  List<num> l = [3, 2.718];
  test3(l[0], l[1]);
}