LanguageFeatures/Set-literals/type_inference_A08_t01.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 To infer the type of element:
/// ...
/// If element is a spreadElement with expression e1:
///
/// If P is ? then let S be the inferred type of e1 in context ?:
/// ...
/// If S is a non-Null subtype of Map<Object, Object>, then the inferred key type
/// of element is K and the inferred value type of element is V, where K and V
/// are the types such that Map<K, V> is a superinterface of S (the result of
/// constraint matching for X and Y using the constraint S <: Map<X, Y>).
///
/// @description Checks that if S is a non-Null subtype of Map<Object, Object>,
/// then the inferred key type of element is K and the inferred value type of
/// element is V, where K and V are the types such that Map<K, V> is a
/// superinterface of S
/// @author sgrekhov@unipro.ru

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

void test1<T extends Map<num, String>>(T t) {
  var m1 = {...t};
  var m2 = {...?t};
//          ^^^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
//              ^
// [cfe] Operand of null-aware operation '...?' has type 'T' which excludes null.
  Expect.isTrue(m1 is Map<num, String>);
  Expect.isTrue(m2 is Map<num, String>);
  Expect.isFalse(m1 is Map<int, String>);
  Expect.isFalse(m2 is Map<int, String>);
  Expect.runtimeIsType<Map<num, String>>(m1);
  Expect.runtimeIsType<Map<num, String>>(m2);
  Expect.runtimeIsNotType<Map<int, String>>(m1);
  Expect.runtimeIsNotType<Map<int, String>>(m2);
}

void test2<T extends Map<Object, Object>>(T t) {
  var m1 = {...t};
  var m2 = {...?t};
//          ^^^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
//              ^
// [cfe] Operand of null-aware operation '...?' has type 'T' which excludes null.
  Expect.isTrue(m1 is Map<Object, Object>);
  Expect.isTrue(m2 is Map<Object, Object>);
  Expect.isFalse(m1 is Map<int, String>);
  Expect.isFalse(m2 is Map<int, String>);
}

main() {
  int x = 1;
  test1({1: "1", 2: "2", 3: "3"});
  test2({1: "1", 2: "2", 3: "3"});
}