fix(linter/no-unused-vars): improve type-only rest parameters diagnostic#22385
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Pull request overview
This PR updates the eslint/no-unused-vars rule implementation to correctly classify rest parameters that are referenced only in TypeScript type positions (e.g. typeof args, return type predicates) as “only used as a type”, aligning diagnostics with expected behavior.
Changes:
- Treat
FormalParameterRestdeclarations as eligible for return-type-predicate “type-only usage” detection. - Update rest-parameter diagnostics to use
argsIgnorePatternand to emit the “only used as a type” message when appropriate. - Add new regression test cases and update the corresponding snapshot output.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| crates/oxc_linter/src/snapshots/eslint_no_unused_vars@oxc-arguments.snap | Updates snapshot to include the new diagnostics for type-only rest parameters and argsIgnorePattern behavior. |
| crates/oxc_linter/src/rules/eslint/no_unused_vars/usage.rs | Extends return type predicate usage detection to include FormalParameterRest. |
| crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/oxc.rs | Adds failing test cases covering type-only rest parameter references and argsIgnorePattern behavior. |
| crates/oxc_linter/src/rules/eslint/no_unused_vars/mod.rs | Ensures rest parameter diagnostics use args_ignore_pattern and set the type-only diagnostic flag when applicable. |
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camchenry
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May 13, 2026
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overlookmotel
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May 15, 2026
# Oxlint ### 🚀 Features - 5478fb5 linter/jsdoc: Implement `require-throws-description` rule (#22386) (Mikhail Baev) - b46d4de linter: Add `--debug` options and add per-rule timing info (#22282) (camchenry) - c73225e linter/eslint: Implement `prefer-arrow-callback` rule (#22312) (박천(Cheon Park)) - de82b59 linter: Add support for `eslint-plugin-jsx-a11y-x` (#22356) (mehm8128) - b170da3 linter: Implement no-implicit-globals (#22249) (Jovi De Croock) - f44b6c8 linter: Fill schemas `DummyRuleMap` with built-in rules (#22288) (Sysix) - 5cdb80d linter/jsx-a11y/: Implement no-interactive-element-to-noninteractive-role (#22332) (anarefolio) - 2749422 linter/jsx-a11y: Add no-noninteractive-element-interactions (#22337) (Pablo Tovar) - ba2a1d3 linter/jsdoc: Implement `require-throws-type` rule (#22358) (Mikhail Baev) - d90729d linter/jsx-a11y: Implement control-has-associated-label (#21985) (mehm8128) - 1d04903 linter/jsdoc: Implement `require-yields-type` rule (#22331) (Mikhail Baev) ### 🐛 Bug Fixes - 04c4609 linter/no-nullable-type-assertion-style: Mark as suggestion (#22450) (camc314) - 1c2b7ec linter/no-unused-vars: Handle shadowed self assignments (#22387) (camc314) - 9faa1d5 linter/no-noninteractive-tabindex: Check conditional expressions (#22435) (camc314) - 0854b3a linter/prefer-arrow-callback: Preserve TSX generic arrows in fixer (#22434) (camc314) - 410b814 linter: Supply `source_type` to codegen fixer (#22433) (camc314) - 3c1bb6f linter: Skip per-node dispatch for run_once-only rules in large files (#22398) (Connor Shea) - 5206cde linter/no-unused-vars: Improve type-only rest parameters diagnostic (#22385) (camc314) - c9a22b5 linter/consistent-function-scoping: Allow imported bindings (#22384) (camc314) - c1e966d linter: Report type-only unused parameters in no-unused-vars (#22368) (camchenry) - 4818d98 linter: Check whether path is under root before ignoring it (#20101) (Leonabcd123) - 41fcdcf linter: Fix rule count not including override rules (#19898) (Daniel Osmond) - 59b4f0e linter: Fix 'explicit-module-boundary-types' false positive with 'allowOverloadFunctions' (#22341) (camchenry) ### ⚡ Performance - 6d42395 linter: Narrow no-unsafe-optional-chaining dispatch (#22437) (camchenry) - 08595fb linter: Optimize no-unreachable (#22397) (camchenry) - 3b46a8d linter: Optimize `no-loss-of-precision` (#22395) (camchenry) - b3e2dc9 linter: Optimize `oxc/bad-array-method-on-arguments` (#22393) (camchenry) ### 📚 Documentation - dcbf62c linter: Remove some duplicate spaces (#22359) (camc314) # Oxfmt ### 💥 BREAKING CHANGES - 21bb5d1 oxfmt: [**BREAKING**] Avoid config pre-scan (#22258) (leaysgur) ### 🐛 Bug Fixes - 441d724 oxfmt: Fix "race probe" logic with unit tests (#22378) (leaysgur) - e49ee26 formatter: Respect `singleQuote` for jsdoc `import()` type paths (#22353) (Colin Lienard) - 43b9978 formatter/sort_imports: Treat subpath imports as internal (#22440) (leaysgur) - 7c5cfa0 formatter: Handle jsx trailing comment with parens (#22370) (leaysgur) - ac5f120 formatter: Fix erroneous formatting inside a template literal with parentheses (#22262) (Jovi De Croock) - 3c53a95 formatter/sort_imports: Handle ignore comment as boundary (#22369) (leaysgur) - 4dd83dd oxfmt: Send expandedStates variants as shared refs (#22366) (leaysgur) - 055cc61 formatter: Expand JSX logical chain with leading line comment (#22346) (leaysgur) - 8046222 formatter: Preserve type alias comment break (#22261) (Jovi De Croock) ### ⚡ Performance - 123c493 oxfmt: Reduce more syscalls (#22380) (leaysgur) Co-authored-by: overlookmotel <557937+overlookmotel@users.noreply.github.com>
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follup up to #22368