blob: 03092564d837540ab4ba2ba8c2a9fc820d684dd2 [file] [log] [blame]
// Copyright (c) 2017, 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.
import "package:expect/expect.dart";
class A {}
class B extends A {}
class B2 extends A {}
class C {
void f(B x, B y) {}
abstract class I {
void f(covariant A x, B y);
// This class contains a forwarding stub for f to allow it to satisfy the
// interface I, while still ensuring that the x argument is type checked before
// C.f is executed.
// For purposes of static type checking, the interface of the class D is
// considered to contain a method f with signature (A, B) -> void. For purposes
// of runtime behavior, a tearoff of D.f is considered to have the reified
// runtime type (Object, B) -> void.
class D extends C implements I {}
main() {
var d = new D();
I i = d;
A a = new A();
B b = new B();
B2 b2 = null;
d.f(b2, b); // Ok since B2 assignable to A
i.f(b2, b); // Ok since B2 assignable to A
void Function(Object, B) g = d.f; // Ok; D.f reified as (Object, B) -> void
Expect.throwsTypeError(() {
d.f(a, b);
Expect.throwsTypeError(() {
i.f(a, b);