fix(parser): fix conditional expressions with arrow-function alternates in TS#20356
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Pull request overview
Fixes a TypeScript parsing edge case where conditional expressions involving arrow functions (notably with TS return type annotations) could be parsed incorrectly, and adds a misc coverage case to exercise the scenario.
Changes:
- Adjusted arrow-function parsing to respect
allow_return_type_in_arrow_functionwhen the arrow head is unambiguous. - Added a new misc/pass TypeScript coverage case for a conditional expression whose alternate is an arrow function with an explicit return type.
- Updated coverage snapshots to reflect the additional misc case (and its current semantic-transform-check outcome).
Reviewed changes
Copilot reviewed 1 out of 7 changed files in this pull request and generated no comments.
Show a summary per file
| File | Description |
|---|---|
crates/oxc_parser/src/js/arrow.rs |
Fixes conditional/arrow parsing behavior by honoring the return-type allowance flag for parenthesized arrows. |
tasks/coverage/misc/pass/conditional-arrow-alternate-return-type.ts |
Adds a repro-style misc pass case covering a conditional with an arrow-function alternate using a TS return type. |
tasks/coverage/snapshots/parser_misc.snap |
Snapshot updated for the new misc case count. |
tasks/coverage/snapshots/transformer_misc.snap |
Snapshot updated for the new misc case count. |
tasks/coverage/snapshots/codegen_misc.snap |
Snapshot updated for the new misc case count. |
tasks/coverage/snapshots/formatter_misc.snap |
Snapshot updated for the new misc case count. |
tasks/coverage/snapshots/semantic_misc.snap |
Snapshot updated; now records an additional semantic transform-check mismatch triggered by the new misc case. |
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### 🚀 Features - e7163b6 ecmascript: Add known-globals to side-effect-free property reads (#20212) (Dunqing) - 139ab68 ecmascript: Add `property_write_side_effects` to `MayHaveSideEffectsContext` (#20217) (Dunqing) ### 🐛 Bug Fixes - 78c264a parser: Fix conditional expressions with arrow-function alternates in TS (#20356) (camc314) - 5c97b14 minifier: Recognize object spread of object literals as side-effect-free (#20299) (Boshen) - 1ff5c1d transformer/typescript: Rewrite extensions in dynamic `import()` expressions (#20121) (Sverre Johansen) - 1c07b3b diagnostics: Handle `WouldBlock` in stdout writes to prevent panic (#20295) (Boshen) - ade14d4 ecmascript: Enhance side-effect detection for classes, TypedArrays, computed members, and spread (#20213) (Dunqing) ### ⚡ Performance - 5474d0a semantic: V8-style walk-up reference resolution (#20292) (Boshen) ### 📚 Documentation - e4aa5b5 parser/napi, linter/plugins: Add JSDoc comments to raw transfer constants (#20286) (overlookmotel) Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>
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fixes rolldown/rolldown#8676