fix(transformer): ignore @jsxImportSource inside inline code spans in comments

[Dunqing]

Summary

• Fix JSX pragma scanner incorrectly matching @jsxImportSource inside backtick code spans (e.g. `@jsxImportSource custom/source`) in doc comments
• Add validation that @ must be preceded by whitespace, *, or be at the start of the comment

Problem

The memchr-based @ search found pragma directives anywhere in a comment, including inside inline code spans. This caused:

1. A @jsxImportSource inside a doc comment overriding the actual file-level pragma
2. The trailing backtick being included in the import specifier (custom/source`)

This broke Vite 8 dev server when .tsx files had JSDoc comments mentioning @jsxImportSource.

Design

Tool	@ position check
esbuild	None — matches @jsx anywhere in comment
Babel	Full start-of-line regex (^\s*(?:\*\s*)?@jsx)
Oxc (this PR)	Preceding byte must be whitespace, *, or start of comment

We intentionally sit between esbuild and Babel — checking only the immediately preceding byte is sufficient for the backtick case without being as strict as Babel's full start-of-line regex.

Fixes #20669

Test plan

• Unit tests added for backtick-wrapped pragmas
• Conformance test fixture added (issue-20669)
• All existing transformer tests pass
• Clippy clean

🤖 Generated with Claude Code

[Dunqing]

• perf(transformer): only scan comments before first statement for JSX pragmas #20675
• fix(transformer): ignore @jsxImportSource inside inline code spans in comments #20674 👈 (View in Graphite)
• main

---

How to use the Graphite Merge Queue

Add either label to this PR to merge it via the merge queue:

• 0-merge - adds this PR to the back of the merge queue
• hotfix - for urgent changes, fast-track this PR to the front of the merge queue

You must have a Graphite account in order to use the merge queue. Sign up using this link.

An organization admin has enabled the Graphite Merge Queue in this repository.

Please do not merge from GitHub as this will restart CI on PRs being processed by the merge queue.

This stack of pull requests is managed by Graphite. Learn more about stacking.

[codspeed-hq]

Merging this PR will improve performance by 3.2%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
✅ 48 untouched benchmarks
⏩ 7 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	mangler[RadixUIAdoptionSection.jsx_keep_names]	20.1 µs	19.5 µs	+3.2%

---

_{Comparing fix/jsx-pragma-backtick (9439b5d) with main (2917bb2)²}

Footnotes

1. 7 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. ↩

2. No successful run was found on main (6b5cd8c) during the generation of this report, so 2917bb2 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[sapphi-red]

It seems TypeScript has the same behavior with us (and esbuild).
TS playground

That said, I think it is safe to diverge for this bit.

[graphite-app]

Merge activity

• Mar 24, 9:22 AM UTC: Dunqing added this pull request to the Graphite merge queue.
• Mar 24, 9:26 AM UTC: Merged by the Graphite merge queue.