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f2b8efde4d
Change-Id: I34abe6993e0dc85d1234878c91ce735139b9cb47 Reviewed-on: https://dart-review.googlesource.com/31750 Reviewed-by: Leaf Petersen <leafp@google.com> Commit-Queue: Paul Berry <paulberry@google.com>
47 lines
1.2 KiB
Dart
47 lines
1.2 KiB
Dart
// Copyright (c) 2017, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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import "package:expect/expect.dart";
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class A {}
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class B extends A {}
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class B2 extends A {}
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class C {
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void f(B x, B y) {}
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}
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abstract class I {
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void f(covariant A x, B y);
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}
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// This class contains a forwarding stub for f to allow it to satisfy the
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// interface I, while still ensuring that the x argument is type checked before
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// C.f is executed.
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//
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// For purposes of static type checking, the interface of the class D is
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// considered to contain a method f with signature (A, B) -> void. For purposes
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// of runtime behavior, a tearoff of D.f is considered to have the reified
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// runtime type (Object, B) -> void.
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class D extends C implements I {}
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main() {
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var d = new D();
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I i = d;
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A a = new A();
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B b = new B();
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B2 b2 = null;
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d.f(b2, b); // Ok since B2 assignable to A
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i.f(b2, b); // Ok since B2 assignable to A
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void Function(Object, B) g = d.f; // Ok; D.f reified as (Object, B) -> void
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Expect.throwsTypeError(() {
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d.f(a, b);
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});
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Expect.throwsTypeError(() {
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i.f(a, b);
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});
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}
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