Paul Berry
3713c0e264
In https://dart-review.googlesource.com/c/sdk/+/299400, the parser was adjusted so that it no longer accepts `when` and `as` as the names for variable patterns in cases where there is a possible ambiguity (e.g. `int when` is not accepted as a pattern because `int` is a legitimate pattern, therefore `when` could introduce a guard clause). This change further prohibits `when` and `as` from being the names of variable patterns or identifier patterns even in the case where there is no ambiguity. This is in line with the discussion at https://github.com/dart-lang/sdk/issues/52199#issuecomment-1526297771, and the spec change at https://github.com/dart-lang/language/pull/3033. Three new error codes are introduced, to cover the three circumstances in which `when` or `as` might be used illegally: in a declared variable pattern, in an assigned variable pattern, or in an identifier pattern. I've also added analyzer tests to ensure that the parser recovers from these errors nicely. Unfortunately, nice error recovery is only feasible in the non-ambiguous cases. I've also updated the language test expectations in `tests/language/patterns/version_2_32_changes_error_test.dart` to reflect the new error messages, and added a few more examples of uses of `when` and `as` that are still permitted. Fixes #52260. Bug: https://github.com/dart-lang/sdk/issues/52260 Change-Id: I229f627aa639659c30b83c74895759207da279f7 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/301482 Reviewed-by: Konstantin Shcheglov <scheglov@google.com> Reviewed-by: Jens Johansen <jensj@google.com> Commit-Queue: Paul Berry <paulberry@google.com>
14 lines
326 B
Plaintext
14 lines
326 B
Plaintext
void f(x) {
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switch (x) {
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case var when:
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}
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}
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void[KeywordToken] f[StringToken]([BeginToken]x[StringToken])[SimpleToken] {[BeginToken]
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switch[KeywordToken] ([BeginToken]x[StringToken])[SimpleToken] {[BeginToken]
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case[KeywordToken] var[KeywordToken] when[KeywordToken]:[SimpleToken]
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}[SimpleToken]
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}[SimpleToken]
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[SimpleToken]
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