Paul Berry
104ac30cf4
The listener API for variable patterns is split into three separate functions, to handle the three separate behaviors: - `handleAssignedVariablePattern` for variable names appearing in an assignment context (these assign to an existing variable upon a successful match). - `handleDeclaredVariablePattern` for variable declarations appearing in a declaration or matching context (these cause a new variable name to come into scope). - `handleWildcardPattern` for wildcards in any context (these don't capture the matched value). Also, responsibility is shifted to the parser for reporting the following error conditions: - VariablePatternKeywordInDeclarationContext (e.g. `var (var x) = ...;`) - PatternAssignmentDeclaresVariable (e.g. `[x, var y] = ...;`) Previously these errors were detected by the implementations, and weren't fully covering all possible error scenarios. In the case of VariablePatternKeywordInDeclarationContext, the listener method `handleDeclaredVariablePattern` is called instead of `handleAssignedVariablePattern`. This ensures that no tokens are dropped from the analyzer AST. The CFE uses the `inAssignmentPattern` argument of `handleDeclaredVariablePattern` to distinguish this error recovery case from a legitimate declared variable pattern. Fixes #51868. Bug: https://github.com/dart-lang/sdk/issues/51868 Change-Id: I28ec679b73d64033166721c6460be35f15e23171 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/291583 Reviewed-by: Jens Johansen <jensj@google.com> Commit-Queue: Paul Berry <paulberry@google.com>
26 lines
613 B
Dart
26 lines
613 B
Dart
// Copyright (c) 2023, 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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// SharedOptions=--enable-experiment=patterns
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// Test that no errors are generated if a wildcard pattern appears inside a
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// pattern variable declaration statement.
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import "package:expect/expect.dart";
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void bareUnderscore() {
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var [x, _] = [0, 1];
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Expect.equals(0, x);
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}
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void usingType() {
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var [x, int _] = [0, 1];
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Expect.equals(0, x);
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}
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main() {
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bareUnderscore();
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usingType();
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}
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