Lasse R.H. Nielsen
5430e68680
Change-Id: I6d5e15ff2d432202618fbc490969a65a9181816d Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/396281 Reviewed-by: Nicholas Shahan <nshahan@google.com> Commit-Queue: Lasse Nielsen <lrn@google.com>
47 lines
1.5 KiB
Dart
47 lines
1.5 KiB
Dart
// Copyright (c) 2021, 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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// Checks what happens if a const map can has a key which overrides `hashCode`
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// in a nasty way.
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// Overriding `hashCode` in const map keys was made an error in Dart 3.0.
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// @dart=2.19
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import 'package:expect/expect.dart';
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/// Returns its argument.
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///
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/// Prevents static optimizations and inlining.
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@pragma('vm:never-inline')
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@pragma('dart2js:noInline')
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dynamic getValueNonOptimized(dynamic x) {
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// DateTime.now() cannot be predicted statically, never equal to 42.
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if (DateTime.now().millisecondsSinceEpoch == 42) {
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return getValueNonOptimized(2);
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}
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return x;
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}
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class Nasty {
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final int n;
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const Nasty(this.n);
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int get hashCode {
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throw "Evil hashCode";
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}
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}
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main() {
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// Test that when using an instance of a custom class as a key in a const Map,
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// its hash code is computed as its identity hash, and even if the class
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// overrides `hashCode`, that `hashCode` implementation is not called.
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final map = const {1: 42, 'foo': 499, 2: 'bar', Nasty(1): 'baz'};
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Expect.equals(42, map[getValueNonOptimized(1.0)]);
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Expect.equals(
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499, map[getValueNonOptimized(new String.fromCharCodes('foo'.runes))]);
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Expect.equals('bar', map[getValueNonOptimized(2)]);
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Expect.isNull(map[getValueNonOptimized(Nasty(1))]);
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Expect.equals('baz', map[getValueNonOptimized(const Nasty(1))]);
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}
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