dart-sdk/tests/language/least_upper_bound/least_upper_bound_function_test.dart

// Copyright (c) 2020, 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.

// Test least upper bound for a Function type and a type that doesn't match
// any of the cases for function types being subtypes of each other.

import 'dart:async';
import '../static_type_helper.dart';

bool condition = true;

void main() {
  void f1(void Function() x, Object y) {
    var z = condition ? x : y;
    z.expectStaticType<Exactly<Object>>();
  }

  void f2(int x, void Function<X>() y) {
    var z = condition ? x : y;
    z.expectStaticType<Exactly<Object>>();
  }

  void f3(double Function(int, int) x, FutureOr<Function> y) {
    var z = condition ? x : y;
    z.expectStaticType<Exactly<Object>>();
  }

  void f4(FutureOr<Function?> x, Function(int i, {int j}) y) {
    var z = condition ? x : y;
    // Expecting `Object?`. Check that the type is a top type.
    z.expectStaticType<Exactly<Object?>>();
    // Check that it is `Object?`.
    if (z == null) throw 0;
    z.expectStaticType<Exactly<Object>>();
  }

  void f5(Function Function<Y>([Y y]) x, dynamic y) {
    var z = condition ? x : y;
    // Check that the type of `z` is `dynamic`.
    Never n = z; // It is `dynamic` or `Never`.
    z = 0; // It is a supertype of `int`.
    z = false; // It is a supertype of `bool`.
  }

  void f6(Never x, Never Function() y) {
    var z = condition ? x : y;
    z.expectStaticType<Exactly<Never Function()>>();
  }

  void f7(Function(Function) x, Null y) {
    var z = condition ? x : y;
    z.expectStaticType<Exactly<Function(Function)?>>();
  }
}