fix(useAwait): treat yield* as async operation in async generators

[FrankFMY]

Summary

Fixes #8645.

yield* in an async generator function delegates to an AsyncIterable, which requires the async modifier. The useAwait rule was incorrectly flagging these functions as missing await.

This PR adds yield* (i.e. JsYieldExpression with a star_token) to the set of expressions recognized as async operations by the MissingAwaitVisitor, alongside await and for await...of.

Changes

• use_await.rs: Added a check for JsYieldExpression with star_token() in the visitor's WalkEvent::Enter branch
• valid.js: Added test cases for async function* with yield*
• invalid.js: Added test case for async function* with plain yield (should still be flagged)
• Updated snapshots

Test plan

• cargo test -p biome_js_analyze -- use_await — all 4 tests pass
• Valid: async function* yieldStarAsyncIterable() { yield* otherAsyncGenerator(); } — no diagnostic
• Invalid: async function* yieldWithoutStar() { yield 1; } — correctly flagged

[changeset-bot]

🦋 Changeset detected

Latest commit: 3f3e4e7

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 13 packages

Name	Type
@biomejs/biome	Patch
@biomejs/cli-win32-x64	Patch
@biomejs/cli-win32-arm64	Patch
@biomejs/cli-darwin-x64	Patch
@biomejs/cli-darwin-arm64	Patch
@biomejs/cli-linux-x64	Patch
@biomejs/cli-linux-arm64	Patch
@biomejs/cli-linux-x64-musl	Patch
@biomejs/cli-linux-arm64-musl	Patch
@biomejs/wasm-web	Patch
@biomejs/wasm-bundler	Patch
@biomejs/wasm-nodejs	Patch
@biomejs/backend-jsonrpc	Patch

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[coderabbitai]

Walkthrough

This pull request fixes the useAwait linter rule to correctly handle async generator functions that use yield* delegation. Previously, the rule would incorrectly flag async generators using yield* as not requiring the async modifier. The fix introduces detection for yield* expressions with async iterables and includes test cases to validate both invalid patterns (regular yield without star) and valid patterns (async generators properly delegating via yield*).

Suggested labels

A-Linter, L-JavaScript, A-Diagnostic

Suggested reviewers

• Conaclos
• dyc3

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely summarizes the main change: fixing the useAwait rule to recognize yield* as an async operation in async generators.
Description check	✅ Passed	The description is well-detailed and clearly related to the changeset, explaining the problem, solution, and test results for the yield* delegation fix.
Linked Issues check	✅ Passed	The PR fully addresses issue #8645 by implementing detection of yield* as an async operation in the useAwait rule, preventing false positives when delegating to async iterables.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to fixing the useAwait rule for yield* expressions; no unrelated modifications are present.

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✨ Finishing touches

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🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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[codspeed-hq]

CodSpeed Performance Report

Merging this PR will not alter performance

_{Comparing FrankFMY:fix/use-await-yield-star (3f3e4e7) with main (51c158e)¹}

Summary

✅ 58 untouched benchmarks
⏩ 95 skipped benchmarks²

Footnotes

1. No successful run was found on main (5a341b2) during the generation of this report, so 51c158e was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

2. 95 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. ↩

[ematipico]

Another AI PR not disclosed...

[FrankFMY]

Hey, fair point — I used Claude Code as an assistant while working on this. I should have disclosed it per your contributing guidelines, my apologies. I'll make sure to include AI disclosure in future PRs.