fix(parser): preserve @__NO_SIDE_EFFECTS__ annotation with parenthesized expressions#17711
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graphite-app[bot] merged 1 commit intomainfrom Jan 7, 2026
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cc @sapphi-red you may want to take a look at this |
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Pull request overview
This PR fixes a bug where @__NO_SIDE_EFFECTS__ annotations were being lost when applied to parenthesized function expressions. The issue occurred in Vue's source code where functions were annotated and wrapped in parentheses like /* @__NO_SIDE_EFFECTS__ */ ((x) => x).
The fix addresses two root causes:
- Lexer checkpoints now preserve trivia flags (
has_pure_commentandhas_no_side_effects_comment) across lookahead operations parse_parenthesized_expressionnow captures the annotation flag before bumping the opening(token and propagates it to nested arrow/function expressions
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| crates/oxc_parser/src/lexer/mod.rs | Added has_pure_comment and has_no_side_effects_comment fields to LexerCheckpoint struct and updated checkpoint save/restore logic to preserve trivia annotation flags across lexer rewind operations |
| crates/oxc_parser/src/js/expression.rs | Modified parse_parenthesized_expression to capture @__NO_SIDE_EFFECTS__ annotation before consuming the opening parenthesis and set the pure flag on nested arrow/function expressions |
| crates/oxc_codegen/tests/integration/snapshots/pure_comments.snap | Added snapshot expectations for 4 test cases covering parenthesized arrow and function expressions with @__NO_SIDE_EFFECTS__ annotation |
| crates/oxc_codegen/tests/integration/comments.rs | Added 4 test cases for @__NO_SIDE_EFFECTS__ annotation preservation with parenthesized expressions: multi-param arrow function, single-param arrow function, anonymous function expression, and named function expression |
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sapphi-red
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Jan 7, 2026
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…sized expressions (#17711) Fixes #17670 Two issues caused the annotation to be lost: 1. LexerCheckpoint did not save/restore trivia flags, so lookahead operations would reset them 2. parse_parenthesized_expression did not capture the annotation before bumping `(` monitor oxc https://github.com/oxc-project/monitor-oxc/actions/runs/20745400998/job/59561563786 CI is not yet green, but the codegen diff looks a lot better
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### 🚀 Features - 10426af codegen: Print soft space between inline block comments on the same line (#17799) (camc314) - 2261e6e semantic: Improve error message to add `#` for private identifiers (#17779) (Dunqing) ### 🐛 Bug Fixes - 7422b7e parser/trivia: Correctly mark whether a block comment is on a newline (#17754) (camc314) - c32e8d5 codegen: Wrap `TSAsExpression` in parens when used with in/instanceof operators (#17752) (camc314) - 5755b2d semantic: Report duplicate private identifier for static and instance elements (#17591) (camc314) - 0600df3 isolated_declarations: Only print jsdoc comments (#17748) (camc314) - ef7e014 parser: Preserve `@__NO_SIDE_EFFECTS__` annotation with parenthesized expressions (#17711) (camc314) - 59a6228 parser: Detect TS1363 error for type-only imports with mixed default and named/namespace bindings (#17712) (Copilot) ### ⚡ Performance - 864f1fa semantic: Mark duplicate class element error reporting as cold (#17746) (camc314) - 3a452b8 semantic: Use smallvec for storing reference IDs (#17731) (camchenry) - d5979dc minifier: Do not allocate when checking to convert `const` to `let` (#17730) (camchenry) - 3f4429c parser: Do not re-allocate TS interface heritage (#17692) (camchenry) ### 📚 Documentation - 120a27c minifier: Add prettier-ignore for js-in-md part (#17687) (leaysgur) Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>
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Fixes #17670
Two issues caused the annotation to be lost:
(monitor oxc https://github.com/oxc-project/monitor-oxc/actions/runs/20745400998/job/59561563786
CI is not yet green, but the codegen diff looks a lot better