Chloe Stefantsova
617d0a8e96
This is a preparation for removing the subtype checking procedure that ignores the nullability in the input types. Change-Id: I3c1db55abde0433e9059d949f1c98aaeb61e210c Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/428980 Commit-Queue: Chloe Stefantsova <cstefantsova@google.com> Reviewed-by: Erik Ernst <eernst@google.com> Reviewed-by: Johnni Winther <johnniwinther@google.com>
59 lines
2.4 KiB
Dart
59 lines
2.4 KiB
Dart
// Copyright (c) 2015, 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.
|
|
|
|
// Verify that '??' binds tighter than '?:' and less tightly than '||'.
|
|
|
|
import "package:expect/expect.dart";
|
|
|
|
main() {
|
|
// Make sure the "none" test fails if "??" is not implemented. This makes
|
|
// status files easier to maintain.
|
|
var _ = null ?? null;
|
|
|
|
dynamic falsity = false;
|
|
dynamic truth = true;
|
|
dynamic one = 1;
|
|
dynamic two = 2;
|
|
|
|
// "a ?? b ?? c" should be legal, and should evaluate to the first non-null
|
|
// value (or null if there are no non-null values).
|
|
Expect.equals(1, one ?? two ?? 3);
|
|
Expect.equals(2, null ?? two ?? 3);
|
|
Expect.equals(3, null ?? null ?? 3);
|
|
Expect.equals(null, null ?? null ?? null);
|
|
|
|
// "a ?? b ? c : d" should parse as "(a ?? b) ? c : d", therefore provided
|
|
// that a is true, b need not be a bool. An incorrect parse of
|
|
// "a ?? (b ? c : d)" would require b to be a bool to avoid a static type
|
|
// warning.
|
|
Expect.equals(2, truth ?? 1 ? 2 : 3);
|
|
|
|
// "a ?? b || c" should parse as "a ?? (b || c)", therefore it's a static
|
|
// type warning if b doesn't have type bool. An incorrect parse of
|
|
// "(a ?? b) || c" would allow b to have any type provided that a is bool.
|
|
falsity ?? 1 || true;
|
|
// ^
|
|
// [analyzer] COMPILE_TIME_ERROR.NON_BOOL_OPERAND
|
|
// [cfe] A value of type 'int' can't be assigned to a variable of type 'bool'.
|
|
|
|
// "a || b ?? c" should parse as "(a || b) ?? c", therefore it is a static
|
|
// type warning if b doesn't have type bool. An incorrect parse of
|
|
// "a || (b ?? c)" would allow b to have any type provided that c is bool.
|
|
falsity || 1 ?? true;
|
|
// ^
|
|
// [analyzer] COMPILE_TIME_ERROR.NON_BOOL_OPERAND
|
|
// [cfe] A value of type 'int' can't be assigned to a variable of type 'bool'.
|
|
// ^^^^
|
|
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
|
|
|
|
// An incorrect parse of "a || (b ?? c)" would result in no checked-mode
|
|
// error.
|
|
Expect.throwsAssertionError(() => false || null ?? true);
|
|
// ^^^^
|
|
// [analyzer] COMPILE_TIME_ERROR.NON_BOOL_OPERAND
|
|
// [cfe] A value of type 'Null' can't be assigned to a variable of type 'bool'.
|
|
// ^^^^
|
|
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
|
|
}
|