fix(parser): preserve legal comments with @preserve/@license when preceded by other annotations by Copilot · Pull Request #15929 · oxc-project/oxc

Copilot · 2025-11-21T02:31:11Z

Legal comments like /* @foo @preserve */ were not being preserved when legal comment output was enabled. The parser only checked if the first @ annotation matched known patterns, missing @preserve/@license later in the comment.

Changes

Parser (oxc_parser/src/lexer/trivia_builder.rs)

Add fallback check using contains_license_or_preserve_comment after __PURE__/__NO_SIDE_EFFECTS__ checks
Ensures @license/@preserve detected anywhere in comment text

Example

// Before: Legal comment not detected by parser
/* @foo @preserve */ function foo() {}
// Parser classifies as: CommentContent::None ❌

// After: Legal comment correctly detected
/* @foo @preserve */ function foo() {}
// Parser classifies as: CommentContent::Legal ✅

Related: rolldown/rolldown#7160

Original prompt

/* @foo @preserve */ should be preserved when legal comment output is enabled even if comment output is disabled. rolldown/rolldown#7160 is related

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graphite-app · 2025-11-21T02:31:16Z

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crates/oxc_codegen/src/comment.rs

crates/oxc_codegen/tests/integration/comments.rs

codspeed-hq · 2025-11-21T03:39:42Z

CodSpeed Performance Report

Merging #15929 will not alter performance

_{Comparing copilot/preserve-foo-comment-output (e359825) with main (4b9d8d2)}

Summary

✅ 42 untouched
⏩ 3 skipped¹

3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

Copilot

Pull Request Overview

This PR fixes a bug where legal comments containing @preserve or @license were not being detected when preceded by other annotations like @foo. The parser was only checking if the first @ annotation matched known patterns, missing legal annotations that appeared later in the comment.

Key changes:

Added early returns after detecting __PURE__ and __NO_SIDE_EFFECTS__ annotations to avoid unnecessary fallthrough
Added fallback check using contains_license_or_preserve_comment to detect @license/@preserve anywhere in comment text
Added test coverage for comments with unknown annotations preceding legal annotations

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crates/oxc_parser/src/lexer/trivia_builder.rs

Boshen · 2025-11-21T14:50:14Z

Merge activity

Nov 21, 2:50 PM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Nov 21, 2:50 PM UTC: Boshen added this pull request to the Graphite merge queue.
Nov 21, 2:56 PM UTC: Merged by the Graphite merge queue.

@foo

…ceded by other annotations (#15929) Legal comments like `/* @foo @preserve */` were not being preserved when legal comment output was enabled. The parser only checked if the first `@` annotation matched known patterns, missing `@preserve`/`@license` later in the comment. ## Changes **Parser (`oxc_parser/src/lexer/trivia_builder.rs`)** - Add fallback check using `contains_license_or_preserve_comment` after `__PURE__`/`__NO_SIDE_EFFECTS__` checks - Ensures `@license`/`@preserve` detected anywhere in comment text ## Example ```javascript // Before: Legal comment not detected by parser /* @foo @preserve */ function foo() {} // Parser classifies as: CommentContent::None ❌ // After: Legal comment correctly detected /* @foo @preserve */ function foo() {} // Parser classifies as: CommentContent::Legal ✅ ``` Related: rolldown/rolldown#7160  <details> <summary>Original prompt</summary> > `/* @foo @preserve */` should be preserved when legal comment output is enabled even if comment output is disabled. rolldown/rolldown#7160 is related </details>  --- ✨ Let Copilot coding agent [set things up for you](https://github.com/oxc-project/oxc/issues/new?title=✨+Set+up+Copilot+instructions&body=Configure%20instructions%20for%20this%20repository%20as%20documented%20in%20%5BBest%20practices%20for%20Copilot%20coding%20agent%20in%20your%20repository%5D%28https://gh.io/copilot-coding-agent-tips%29%2E%0A%0A%3COnboard%20this%20repo%3E&assignees=copilot) — coding agent works faster and does higher quality work when set up for your repo.

@foo

…ceded by other annotations (#15929) Legal comments like `/* @foo @preserve */` were not being preserved when legal comment output was enabled. The parser only checked if the first `@` annotation matched known patterns, missing `@preserve`/`@license` later in the comment. ## Changes **Parser (`oxc_parser/src/lexer/trivia_builder.rs`)** - Add fallback check using `contains_license_or_preserve_comment` after `__PURE__`/`__NO_SIDE_EFFECTS__` checks - Ensures `@license`/`@preserve` detected anywhere in comment text ## Example ```javascript // Before: Legal comment not detected by parser /* @foo @preserve */ function foo() {} // Parser classifies as: CommentContent::None ❌ // After: Legal comment correctly detected /* @foo @preserve */ function foo() {} // Parser classifies as: CommentContent::Legal ✅ ``` Related: rolldown/rolldown#7160  <details> <summary>Original prompt</summary> > `/* @foo @preserve */` should be preserved when legal comment output is enabled even if comment output is disabled. rolldown/rolldown#7160 is related </details>  --- ✨ Let Copilot coding agent [set things up for you](https://github.com/oxc-project/oxc/issues/new?title=✨+Set+up+Copilot+instructions&body=Configure%20instructions%20for%20this%20repository%20as%20documented%20in%20%5BBest%20practices%20for%20Copilot%20coding%20agent%20in%20your%20repository%5D%28https://gh.io/copilot-coding-agent-tips%29%2E%0A%0A%3COnboard%20this%20repo%3E&assignees=copilot) — coding agent works faster and does higher quality work when set up for your repo.

@license

### 💥 BREAKING CHANGES - cbb27fd ast: [**BREAKING**] Add `TSGlobalDeclaration` type (#15712) (overlookmotel) ### 🚀 Features - 0c1f82b linter/plugins: Add `tokens` property to `Program` (#16020) (overlookmotel) - 6cff132 span: Add `Span::merge_within` method (#15869) (sapphi-red) - 102365d allocator/vec: Add `Vec::into_bump_slice` method (#15770) (Dunqing) ### 🐛 Bug Fixes - e2ca770 codegen: Add support for printing type arguments in new expressions (#15963) (Ives van Hoorne) - 2bd3cb6 apps, editors, napi: Fix `oxlint-disable` comments (#16014) (overlookmotel) - 622cb5e parser: Preserve legal comments with @preserve/@license when preceded by other annotations (#15929) (copilot-swe-agent) - 7c46a9e transformer/tagged-template-transform: Handle `\n` escape sequences (#15830) (Dunqing) - f386efc minifier: Avoid generating invalid spans (#15778) (sapphi-red) - d4ff004 parser: Forbid invalid modifiers on `module` and `global` (#15723) (overlookmotel) - 2191ae9 semantic: Allow reserved keywords in typescript ambient contexts (#15495) (sapphi-red) - 7d1ebad isolated-declarations: Incorrect nested namespace output in isolated declarations (#15800) (copilot-swe-agent) ### ⚡ Performance - b4b0ed8 transformer/typescript: Reverse order of checks (#15722) (overlookmotel) ### 📚 Documentation - c81a331 data_structures: Doc comments on fields of `Stack` (#15793) (overlookmotel) - cfae31d allocator: Use `allocator` as var name in examples (#15781) (overlookmotel) Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>

@foo

…ceded by other annotations (oxc-project#15929) Legal comments like `/* @foo @preserve */` were not being preserved when legal comment output was enabled. The parser only checked if the first `@` annotation matched known patterns, missing `@preserve`/`@license` later in the comment. ## Changes **Parser (`oxc_parser/src/lexer/trivia_builder.rs`)** - Add fallback check using `contains_license_or_preserve_comment` after `__PURE__`/`__NO_SIDE_EFFECTS__` checks - Ensures `@license`/`@preserve` detected anywhere in comment text ## Example ```javascript // Before: Legal comment not detected by parser /* @foo @preserve */ function foo() {} // Parser classifies as: CommentContent::None ❌ // After: Legal comment correctly detected /* @foo @preserve */ function foo() {} // Parser classifies as: CommentContent::Legal ✅ ``` Related: rolldown/rolldown#7160  <details> <summary>Original prompt</summary> > `/* @foo @preserve */` should be preserved when legal comment output is enabled even if comment output is disabled. rolldown/rolldown#7160 is related </details>  --- ✨ Let Copilot coding agent [set things up for you](https://github.com/oxc-project/oxc/issues/new?title=✨+Set+up+Copilot+instructions&body=Configure%20instructions%20for%20this%20repository%20as%20documented%20in%20%5BBest%20practices%20for%20Copilot%20coding%20agent%20in%20your%20repository%5D%28https://gh.io/copilot-coding-agent-tips%29%2E%0A%0A%3COnboard%20this%20repo%3E&assignees=copilot) — coding agent works faster and does higher quality work when set up for your repo.

@license

### 💥 BREAKING CHANGES - cbb27fd ast: [**BREAKING**] Add `TSGlobalDeclaration` type (oxc-project#15712) (overlookmotel) ### 🚀 Features - 0c1f82b linter/plugins: Add `tokens` property to `Program` (oxc-project#16020) (overlookmotel) - 6cff132 span: Add `Span::merge_within` method (oxc-project#15869) (sapphi-red) - 102365d allocator/vec: Add `Vec::into_bump_slice` method (oxc-project#15770) (Dunqing) ### 🐛 Bug Fixes - e2ca770 codegen: Add support for printing type arguments in new expressions (oxc-project#15963) (Ives van Hoorne) - 2bd3cb6 apps, editors, napi: Fix `oxlint-disable` comments (oxc-project#16014) (overlookmotel) - 622cb5e parser: Preserve legal comments with @preserve/@license when preceded by other annotations (oxc-project#15929) (copilot-swe-agent) - 7c46a9e transformer/tagged-template-transform: Handle `\n` escape sequences (oxc-project#15830) (Dunqing) - f386efc minifier: Avoid generating invalid spans (oxc-project#15778) (sapphi-red) - d4ff004 parser: Forbid invalid modifiers on `module` and `global` (oxc-project#15723) (overlookmotel) - 2191ae9 semantic: Allow reserved keywords in typescript ambient contexts (oxc-project#15495) (sapphi-red) - 7d1ebad isolated-declarations: Incorrect nested namespace output in isolated declarations (oxc-project#15800) (copilot-swe-agent) ### ⚡ Performance - b4b0ed8 transformer/typescript: Reverse order of checks (oxc-project#15722) (overlookmotel) ### 📚 Documentation - c81a331 data_structures: Doc comments on fields of `Stack` (oxc-project#15793) (overlookmotel) - cfae31d allocator: Use `allocator` as var name in examples (oxc-project#15781) (overlookmotel) Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>

Copilot AI assigned Copilot and sapphi-red Nov 21, 2025

Copilot started work on behalf of sapphi-red November 21, 2025 02:31 View session

Copilot AI changed the title ~~[WIP] Preserve legal comment output for foo~~ fix(parser, codegen): preserve legal comments with @preserve/@license when preceded by other annotations Nov 21, 2025

Copilot AI requested a review from sapphi-red November 21, 2025 02:51

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Copilot AI changed the title ~~fix(parser, codegen): preserve legal comments with @preserve/@license when preceded by other annotations~~ fix(parser): preserve legal comments with @preserve/@license when preceded by other annotations Nov 21, 2025

Copilot AI requested a review from sapphi-red November 21, 2025 03:17

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github-actions bot added A-parser Area - Parser C-bug Category - Bug labels Nov 21, 2025

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sapphi-red marked this pull request as ready for review November 21, 2025 03:54

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sapphi-red requested a review from Boshen November 21, 2025 03:57

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Boshen added the 0-merge Merge with Graphite Merge Queue label Nov 21, 2025

graphite-app bot force-pushed the copilot/preserve-foo-comment-output branch from e359825 to 622cb5e Compare November 21, 2025 14:50

graphite-app bot merged commit 622cb5e into main Nov 21, 2025
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graphite-app bot removed the 0-merge Merge with Graphite Merge Queue label Nov 21, 2025

graphite-app bot deleted the copilot/preserve-foo-comment-output branch November 21, 2025 14:56

Boshen mentioned this pull request Nov 24, 2025

release(crates): oxc v0.99.0 #16037

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fix(parser): preserve legal comments with @preserve/@license when preceded by other annotations#15929

fix(parser): preserve legal comments with @preserve/@license when preceded by other annotations#15929
graphite-app[bot] merged 1 commit intomainfrom
copilot/preserve-foo-comment-output

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edited by graphite-app bot

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CodSpeed Performance Report

Merging #15929 will not alter performance

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