fix(linter): recognize stable hook results declared with let

[littleKitchen]

Summary

When useState setters or useRef values are destructured into let bindings, they should still be recognized as stable and not require inclusion in dependency arrays.

Problem

let [a, setA] = useState(0);
let b = useRef("");

useEffect(() => {
  setA(1);
  b.current = "test";
}, []); // ❌ Biome incorrectly reports setA and b as missing dependencies

The useExhaustiveDependencies rule was returning early for non-const declarations without checking if the initializer was a stable hook call.

Solution

Check stable hook results for both let and const declarations. For let declarations, only stable hook results (like useState setters at index 1, or useRef identity) are considered stable.

Test Plan

• Added issue8907.js test case
• All 56 useExhaustiveDependencies tests pass

Fixes #8907

[changeset-bot]

🦋 Changeset detected

Latest commit: caa1010

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 PR fixes the useExhaustiveDependencies rule to correctly recognise stable hook results (like useState setters and useRef values) when declared with let instead of just const. The fix extends the is_stable_binding function to handle non-const declarations by checking for reassignments, validating destructuring patterns, and determining whether initializers are stable React hook calls. Test cases demonstrate the expected behaviour for both stable (non-reassigned) and unstable (reassigned) bindings.

Possibly related PRs

• fix(linter): useExhaustiveDependencies regressions, fixes #8802, fixes #8883, fixes #8885 #8900 — Modifies the same use\_exhaustive\_dependencies lint to refine stability checks for hook results and variable binding patterns.
• fix(linter): useExhaustiveDependencies multiple fixes (fixes #3080, fixes #4248, fixes #5914, fixes #8427, fixes #8484, fixes #3685, fixes #3512, fixes #7982) #8767 — Expands is\_stable\_binding style stability checks to cover hook results and non-const handling with destructuring support.
• fix(lint/useExhaustiveDependencies): correctly fix the dependency list from a shorthand object member #7498 — Improves the same rule's dependency inference by adding JsReferenceIdentifier handling for hook dependencies.

Suggested reviewers

• dyc3
• ematipico

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: fixing the linter to recognize stable hook results declared with let.
Description check	✅ Passed	The description clearly explains the problem, solution, and test plan, all directly related to the changeset.
Linked Issues check	✅ Passed	The PR fully addresses issue #8907 by implementing stable hook result recognition for both let and const declarations, with appropriate test coverage.
Out of Scope Changes check	✅ Passed	All changes are focused on fixing the useExhaustiveDependencies rule and adding related tests; no unrelated modifications detected.

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[dyc3]

cc @mdevils

[mdevils]

@littleKitchen thank you for your contributions! Please check my comments.

[mdevils]

Other values may be reassigned.

All lets may be reassigned. eslint rule checks specifically if it was reassigned in case of stable hook results. Please check all writes of the binding to make sure it wasn't rewritten.

[littleKitchen]

I see, thanks for the review.

[mdevils]

@littleKitchen thank you for your quick response and fixes!

Please include a changeset for your changes.

Here is an example changeset: https://github.com/biomejs/biome/blob/main/.changeset/ninety-tigers-fetch.md

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[codspeed-hq]

Merging this PR will not alter performance

✅ 58 untouched benchmarks
⏩ 95 skipped benchmarks¹

---

_{Comparing littleKitchen:fix/8907-let-useState-stable (caa1010) with main (d876a38)}

Footnotes

1. 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. ↩

[mdevils]

@littleKitchen thank you for your contribution!

[littleKitchen]

Thanks!