Robert Nystrom
f205141a42
Change-Id: Ib798b9573ee8ec924f87104684934785fadc8189 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/141702 Auto-Submit: Bob Nystrom <rnystrom@google.com> Reviewed-by: Leaf Petersen <leafp@google.com> Reviewed-by: Erik Ernst <eernst@google.com> Reviewed-by: Nicholas Shahan <nshahan@google.com> Commit-Queue: Bob Nystrom <rnystrom@google.com>
44 lines
1.0 KiB
Dart
44 lines
1.0 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 C {
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void f(B x) {}
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}
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abstract class I<T> {
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void f(T x);
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}
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// D contains a forwarding stub for f which ensures that `x` is type checked.
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class D extends C implements I<B> {}
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void checkStubTearoff(dynamic tearoff) {
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// Since the stub's parameter is covariant, its type should be reified as
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// Object.
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Expect.isTrue(tearoff is void Function(Object));
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// Verify that the appropriate runtime check occurs.
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tearoff(new B()); // No error
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Expect.throwsTypeError(() {
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tearoff(new A());
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});
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}
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main() {
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// The same forwarding stub should be torn off from D regardless of what
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// interface is used to tear it off.
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D d = new D();
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C c = d;
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I i = d;
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checkStubTearoff(d.f);
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checkStubTearoff(c.f);
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checkStubTearoff(i.f);
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}
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