Dmitry Stefantsov
e119ccad2a
Closes #43163. Bug: https://github.com/dart-lang/sdk/issues/43163 Change-Id: I55f51eee097a320dcc38cf54a41c9f6684b5dd59 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/162505 Commit-Queue: Dmitry Stefantsov <dmitryas@google.com> Reviewed-by: Johnni Winther <johnniwinther@google.com> Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
82 lines
2.2 KiB
Dart
82 lines
2.2 KiB
Dart
// Copyright (c) 2020, 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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// Tests that inference can solve for T? ~ dynamic or void.
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class C<T extends Object> {
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final T? value;
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const C(this.value);
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C.list(List<T?> list) : value = list.first;
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void set nonNullValue(T value) {}
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}
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List<T> foo<T extends Object>(T? value) => [value!];
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List<T> bar<T extends Object>(List<T?> value) => [
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for (var element in value)
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if (element != null) element
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];
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extension Ext<T extends Object> on List<T?> {
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List<T> whereNotNull() => [
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for (var element in this)
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if (element != null) element
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];
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}
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main() {
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{
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// Testing for dynamic.
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const dynamic o = 42;
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var c = const C(o);
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var f = foo(o);
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var l = [o].whereNotNull();
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c.expectStaticType<Exactly<C<Object>>>();
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Expect.type<C<Object>>(c); // Run-time type is subtype of C<Object>.
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c.nonNullValue = Object(); // And supertype.
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f.expectStaticType<Exactly<List<Object>>>();
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Expect.type<List<Object>>(f); // Run-time type is subtype of List<Object>.
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f[0] = Object(); // And supertype.
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l.expectStaticType<Exactly<List<Object>>>();
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Expect.type<List<Object>>(l); // Run-time type is subtype of List<Object>.
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l[0] = Object(); // And supertype.
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}
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{
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// Testing for void
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List<void> o = <void>[42];
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var c = C.list(o);
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var f = bar(o);
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var l = o.whereNotNull();
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c.expectStaticType<Exactly<C<Object>>>();
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Expect.type<C<Object>>(c); // Run-time type is subtype of C<Object>.
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c.nonNullValue = Object(); // And supertype.
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f.expectStaticType<Exactly<List<Object>>>();
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Expect.type<List<Object>>(f); // Run-time type is subtype of List<Object>.
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f[0] = Object(); // And supertype.
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l.expectStaticType<Exactly<List<Object>>>();
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Expect.type<List<Object>>(l); // Run-time type is subtype of List<Object>.
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l[0] = Object(); // And supertype.
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}
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}
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// Captures and checks static type of expression.
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extension TypeCheck<T> on T {
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T expectStaticType<R extends Exactly<T>>() {
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return this;
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}
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}
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typedef Exactly<T> = T Function(T);
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