perf(linter/plugins): add fast path for files with no comments by overlookmotel · Pull Request #20366 · oxc-project/oxc

overlookmotel · 2026-03-14T01:36:49Z

Optimization to comments deserialization. Files which have no comments are probably fairly common. Add a fast path for this case. We have to branch on length === 0 later on anyway, so might as well branch earlier and exit.

overlookmotel · 2026-03-14T01:37:07Z

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Copilot

Pull request overview

Adds a performance optimization in the oxlint JS plugin layer by short-circuiting comment initialization for files that contain zero comments, reducing work in a common case.

Changes:

Add a shared frozen empty comments array and return early from initComments() when commentsLen === 0.
Minor refactor/simplification of a string replacement in the TypeScript type generator.

Reviewed changes

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

File	Description
`apps/oxlint/src-js/plugins/comments.ts`	Introduces the no-comments fast path and shared empty comments array.
`tasks/ast_tools/src/generators/typescript.rs`	Collapses a multi-line `replacen` call into a single line.

apps/oxlint/src-js/plugins/comments.ts

Copilot

Pull request overview

Adds a fast-path in the JS-side comment deserialization to avoid work for files with zero comments (a common case), while preserving the existing initComments() contract that sourceText is initialized after initialization.

Changes:

Add a shared, reusable empty comments array and early-return in initComments() when commentsLen === 0.
Minor tweak to hashbang/shebang detection logic during comment initialization.
Update oxlint NAPI bindings exports/types (notably removing Severity and several type declarations).

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
apps/oxlint/src-js/plugins/comments.ts	Adds an early-exit fast path for commentless files and reuses a shared empty comments array.
apps/oxlint/src-js/bindings.js	Stops exporting `Severity` from the JS bindings surface.
apps/oxlint/src-js/bindings.d.ts	Removes `Severity` and other previously exported interfaces from the generated TS declarations.

Comments suppressed due to low confidence (1)

apps/oxlint/src-js/bindings.js:586

This PR is described as a comments deserialization perf-only change, but this hunk stops exporting Severity from the oxlint JS bindings. If this export is still part of the expected bindings surface (consistent with other NAPI packages in this repo like napi/parser and apps/oxfmt), this is a breaking change and should either be reverted or called out explicitly (and versioned accordingly).

const { applyFixes, getBufferOffset, lint, parseRawSync, rawTransferSupported } = nativeBinding
export { applyFixes }
export { getBufferOffset }
export { lint }
export { parseRawSync }

apps/oxlint/src-js/plugins/comments.ts

Copilot

Pull request overview

Adds a fast path in the JS-side comments deserializer to avoid per-file comment object setup work when the parsed program contains zero comments, which should reduce overhead for common “no comments” files during lint runs.

Changes:

Introduces a shared frozen emptyComments array and returns it early when commentsLen === 0.
Keeps sourceText initialization eager in initComments() to preserve existing invariants for downstream comment APIs.
Simplifies hashbang (Shebang) detection by checking the first serialized comment’s start offset directly.

overlookmotel · 2026-03-14T13:21:07Z

Merge activity

Mar 14, 1:21 PM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Mar 14, 1:26 PM UTC: overlookmotel added this pull request to the Graphite merge queue.
Mar 14, 1:38 PM UTC: Merged by the Graphite merge queue.

Optimization to comments deserialization. Files which have no comments are probably fairly common. Add a fast path for this case. We have to branch on `length === 0` later on anyway, so might as well branch earlier and exit.

# Oxlint ### 🚀 Features - c95951f linter/plugins: Implement `sourceCode.markVariableAsUsed` (#20357) (overlookmotel) - 7a2a7d0 linter: Implement `n/handle-callback-err` rule (#19616) (Mikhail Baev) ### 🐛 Bug Fixes - f8fbd6e linter/plugins: Remove `hashbang` property from AST (#20365) (overlookmotel) - 6eb5b01 linter/prefer-await-to-then: Ignore Promise static methods (#20347) (camc314) - a4b61f7 linter: Remove `defineConfig` check (#20308) (camc314) - 3ad7f53 linter/explicit-module-boundary-types: False positive with satisfies expr (#20309) (camc314) - f547401 linter/no-unused-private-class-members: Treat switch discriminants as read (#20307) (camc314) - 1c07b3b diagnostics: Handle `WouldBlock` in stdout writes to prevent panic (#20295) (Boshen) ### ⚡ Performance - e4f7248 linter: Remove unnecessary clone of owned String in drain loop (#20388) (Boshen) - 4a67f1d linter: Eliminate Vec allocation in disable directive matching (#20387) (Boshen) - 618a598 linter/plugins: Add fast path for files with no comments (#20366) (overlookmotel) - b0125c5 linter/plugins: Deserialize comments without AST (#20364) (overlookmotel) - 9cd612f linter/plugins: Recycle comment objects (#20362) (overlookmotel) - bf442f8 linter/plugins: Cheaper `Token` creation (#20360) (overlookmotel) - 5474d0a semantic: V8-style walk-up reference resolution (#20292) (Boshen) - 7946eba linter/plugins: Avoid arguments spread and temp array when merging (#20318) (overlookmotel) - fc7cf8a linter/plugins: Pre-define less CFG merger functions (#20317) (overlookmotel) - 3b9eb28 linter/plugins: Streamline getting/creating visit fn mergers (#20319) (overlookmotel) - f04e850 linter/plugins: Inline binary search functions into call sites (#20312) (overlookmotel) - fe24afe linter/plugins: Apply replace globals TSDown plugin to JS files (#20305) (overlookmotel) - 77cdacc linter/plugins: Use array buffer views for tokens (#20301) (overlookmotel) - 910c941 linter/plugins: Reorder branches in `getTokenByRangeStart` (#20296) (overlookmotel) - af7674c linter/tokens: Avoid extra token value allocation (#20013) (camc314) ### 📚 Documentation - 24490b5 linter: Improve formatting for 80ish rules' docs. (#20411) (connorshea) - 3383523 linter: Improve `--tsconfig` flag docs (#20342) (camc314) # Oxfmt ### 🚀 Features - d22c443 oxfmt: Export `OxfmtConfig` type (#20275) (leaysgur) - a11ecff oxfmt/lsp: Respect `angular` language id as `.component.html` file (#20242) (Sysix) ### 🐛 Bug Fixes - ce65099 formatter: Preserve parentheses around as expression before private field access (#20419) (bab) - f908742 oxfmt: Revert #20326 partially (#20413) (leaysgur) - 4ef93ea formatter: Honor trailing ignore comments after list separators (#19925) (Andreas Lubbe) - 68fb0d0 oxfmt: Skip vite.config.ts which fails to import (#20326) (leaysgur) - 88ee826 oxfmt: Handle literalline for script-in-vue (#20130) (leaysgur) - 1c07b3b diagnostics: Handle `WouldBlock` in stdout writes to prevent panic (#20295) (Boshen) Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>

This was referenced Mar 14, 2026

refactor(ast_tools): remove COMMENTS variant modifier from raw transfer codegen #20361

Merged

perf(linter/plugins): recycle comment objects #20362

Merged

refactor(linter/plugins): move comments methods into own file #20363

Merged

This was referenced Mar 14, 2026

perf(linter/plugins): deserialize comments without AST #20364

Merged

fix(linter/plugins): remove hashbang property from AST #20365

Merged

github-actions bot added A-linter Area - Linter A-cli Area - CLI A-linter-plugins Area - Linter JS plugins C-performance Category - Solution not expected to change functional behavior, only performance labels Mar 14, 2026

overlookmotel force-pushed the om/03-13-fix_linter_plugins_remove_hashbang_property_from_ast branch from f7daa9a to b7af7fc Compare March 14, 2026 01:51

overlookmotel force-pushed the om/03-14-perf_linter_plugins_add_fast_path_for_files_with_no_comments branch from dfe4809 to 0af44c0 Compare March 14, 2026 01:51

github-actions bot added the A-ast-tools Area - AST tools label Mar 14, 2026

overlookmotel marked this pull request as ready for review March 14, 2026 02:01

overlookmotel requested a review from camc314 as a code owner March 14, 2026 02:01

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overlookmotel force-pushed the om/03-14-perf_linter_plugins_add_fast_path_for_files_with_no_comments branch from 320dfb8 to 3f0a4f0 Compare March 14, 2026 02:03

overlookmotel force-pushed the om/03-13-fix_linter_plugins_remove_hashbang_property_from_ast branch from dcbfe5f to 03c2e4b Compare March 14, 2026 02:03

overlookmotel self-assigned this Mar 14, 2026

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overlookmotel force-pushed the om/03-14-perf_linter_plugins_add_fast_path_for_files_with_no_comments branch from 3f0a4f0 to 4a39359 Compare March 14, 2026 02:11

overlookmotel force-pushed the om/03-13-fix_linter_plugins_remove_hashbang_property_from_ast branch from 03c2e4b to 10b9cf7 Compare March 14, 2026 02:11

overlookmotel force-pushed the om/03-14-perf_linter_plugins_add_fast_path_for_files_with_no_comments branch from 4a39359 to b9c061d Compare March 14, 2026 02:29

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overlookmotel marked this pull request as draft March 14, 2026 12:14

graphite-app bot changed the base branch from om/03-13-fix_linter_plugins_remove_hashbang_property_from_ast to graphite-base/20366 March 14, 2026 12:18

graphite-app bot force-pushed the graphite-base/20366 branch from 10b9cf7 to f8fbd6e Compare March 14, 2026 12:35

graphite-app bot force-pushed the om/03-14-perf_linter_plugins_add_fast_path_for_files_with_no_comments branch from b9c061d to 7f9bf2c Compare March 14, 2026 12:35

graphite-app bot changed the base branch from graphite-base/20366 to main March 14, 2026 12:36

graphite-app bot force-pushed the om/03-14-perf_linter_plugins_add_fast_path_for_files_with_no_comments branch from 7f9bf2c to cf1a313 Compare March 14, 2026 12:36

overlookmotel force-pushed the om/03-14-perf_linter_plugins_add_fast_path_for_files_with_no_comments branch from cf1a313 to 0bc8d0f Compare March 14, 2026 13:14

overlookmotel marked this pull request as ready for review March 14, 2026 13:15

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overlookmotel added the 0-merge Merge with Graphite Merge Queue label Mar 14, 2026

graphite-app bot force-pushed the om/03-14-perf_linter_plugins_add_fast_path_for_files_with_no_comments branch from 0bc8d0f to 618a598 Compare March 14, 2026 13:27

graphite-app bot merged commit 618a598 into main Mar 14, 2026
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graphite-app bot deleted the om/03-14-perf_linter_plugins_add_fast_path_for_files_with_no_comments branch March 14, 2026 13:38

graphite-app bot removed the 0-merge Merge with Graphite Merge Queue label Mar 14, 2026

Boshen mentioned this pull request Mar 16, 2026

release(apps): oxlint v1.56.0 && oxfmt v0.41.0 #20423

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perf(linter/plugins): add fast path for files with no comments#20366

perf(linter/plugins): add fast path for files with no comments#20366
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om/03-14-perf_linter_plugins_add_fast_path_for_files_with_no_comments

overlookmotel commented Mar 14, 2026 •

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overlookmotel commented Mar 14, 2026 •

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