fix(linter/no-unused-vars): panic when variable is redeclared as function in same scope #11280

Dunqing · 2025-05-25T15:22:53Z

var a;
function a() { a() }

The above code is legal; in this case, the symbol_declaration points to var a rather than function aa because the current implementation handles them in order they declared, thus we need to iterate over symbol_redeclarations to find the function's node id.

Dunqing · 2025-05-25T15:23:12Z

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codspeed-hq · 2025-05-25T15:27:51Z

CodSpeed Instrumentation Performance Report

Merging #11280 will not alter performance

_{Comparing 05-25-fix_linter_no-unused-vars_panic_when_variable_is_redeclared_as_function_in_same_scope (19772e5) with main (4bc2650)}

Summary

✅ 38 untouched benchmarks

Copilot

Pull Request Overview

This PR fixes a panic in the no-unused-vars rule when a variable is redeclared as a function in the same scope by iterating over symbol_redeclarations to find the correct function declaration, and adds a test case to cover this scenario.

Handle redeclarations in usage.rs to select the function’s scope when a variable and function share a name
Add a test_js test in tests/oxc.rs for the redeclaration case

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
crates/oxc_linter/src/rules/eslint/no_unused_vars/usage.rs	Added logic to inspect `symbol_redeclarations` and select the function container scope
crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/oxc.rs	Introduced `test_js` covering redeclared function scenario

Comments suppressed due to low confidence (4)

crates/oxc_linter/src/rules/eslint/no_unused_vars/usage.rs:755

[nitpick] The variable name declaration is a bit generic and shadows the outer context; rename it to something like function_decl for clarity.

let declaration = redeclarations.iter().find(|decl| decl.flags.is_function()).unwrap();

crates/oxc_linter/src/rules/eslint/no_unused_vars/usage.rs:760

There's a duplicated "or" in the debug message ("or or"); please remove the extra word.

"Found a function call or or new expr reference on a node flagged as a function or class, but the symbol's declaration node has no scope id. It should always be a container."

crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/oxc.rs:1296

[nitpick] The test name test_js is quite generic; consider renaming it to something more descriptive like test_redeclared_function_scope.

fn test_js() {

crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/oxc.rs:1299

You might also add a test for the reverse order (e.g. var a; function a() { a(); }) to ensure both declaration patterns are covered.

"export function promisify() { var fn; function fn() {}; return fn; }",

crates/oxc_linter/src/rules/eslint/no_unused_vars/usage.rs

camc314 · 2025-05-25T16:13:58Z

Merge activity

May 25, 4:13 PM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
May 25, 4:39 PM UTC: camc314 added this pull request to the Graphite merge queue.
May 25, 4:42 PM UTC: Merged by the Graphite merge queue.

…tion in same scope (#11280) * close: #11215 * close: #11234 ```js var a; function a() { a() } ``` The above code is legal; in this case, the symbol_declaration points to `var a` rather than `function a`a because the current implementation handles them in order they declared, thus we need to iterate over `symbol_redeclarations` to find the function's node id.

## [0.17.0] - 2025-05-30 - ead5309 linter: [**BREAKING**] Remove react from default plugin set (#11382) (camc314) ### Features - 2d25bd8 linter: Remove `unicorn/no-for-loop` over `typescript/prefer-for-of` (#11354) (camc314) - bbb7eb1 linter: Add auto-fix to react/forward-ref-uses-ref (#11342) (yefan) - 590c27b linter: Add auto-fix to unicorn/no-await-expression-member (#11306) (yefan) - 7824f01 linter: Implement suggestion for `jsx/no-useless-fragment` (#10800) (Cam McHenry) - 2083d33 linter/language_server: Add second editor suggestion for `react/forward-ref-uses-ref` (#11375) (Sysix) ### Bug Fixes - f6424dd linter: Reflect react plugin is disabled by default in cli (#11397) (camc314) - 25ecbfe linter: Remove use of `FrameworkFlags::React` to decide whether rules should run (#11383) (camc314) - 0d240e4 linter: False positive in react/exhaustive-deps with default formal parameter (#11395) (camc314) - c91697e linter: Fix panic in multi byte char in `TryFrom` aria (#11350) (camc314) - 9798ef1 linter: Stack overflow in no-async-endpoint-handlers (#11317) (camc314) - 348ad97 linter: Skip no-unused-vars on astro files (#11303) (camc314) - 183d7f0 linter: Make `jest/no-large-snapshots` error easier to comprehend (#11294) (Ulrich Stark) - 4e606a5 linter: Improve `jest/no-large-snapshots` (#11291) (Ulrich Stark) - 14f790f linter: Improve `jest/no-restricted-matchers` (#11292) (Ulrich Stark) - a2c82be linter/block-scoped-var: Better diagnostic messages (#11290) (DonIsaac) - 19772e5 linter/no-unused-vars: Panic when variable is redeclared as function in same scope (#11280) (Dunqing) - 7af5bb1 oxc_language_server: Include save option for text document sync capability (#11297) (Nicholas Rayburn) ### Performance - 0ed6c1a language_server: Use `Arc<RwLock>` instead of `Mutex` for workspace workers (#11328) (Sysix) - a0ee946 linter: Reduce code size in `globals` (#11333) (shulaoda) - c90c5e9 linter/no-unused-vars: Simplify checking self call usage (#11281) (Dunqing) ### Documentation - eae51ca linter: Clarify jsdoc/check-tag-names configuration (#11394) (Rägnar O'ock) - cd354d4 oxlint: Remove incorrect doc comment (#11326) (camc314) ### Refactor - 42738f0 linter: Shorten code of match arms (#11389) (Ulrich Stark) - 8a34447 linter: Improve `unicorn/text-encoding-identifier-case` (#11386) (shulaoda) - eaa605e linter: Avoid some `Arc::clone` in linter runtime (#11388) (Boshen) - 1cd8b9c linter: Fixes in `react/forward-ref-uses-ref` are suggestions (#11376) (Sysix) - 50ef691 linter: Add `diagnostics_with_multiple_fixes` to `LintContext` (#11357) (Sysix) - 606bb34 linter: Accept `PossibleFixes` instead of `Fix` for `Messages` (#11295) (Sysix) - 042a3f3 linter: Use `PossibleFixes` instead of `Option<Fix>` (#11284) (Sysix) - ffcfb46 linter: Improve `unicorn/throw-new-error` (#11364) (shulaoda) - 8fb55c3 linter: Cleanup docs and simplify code of `eslint/no-fallthrough` (#11331) (Ulrich Stark) - e2f0f0a linter: Improve docs and simplify code of `eslint/no-duplicate-imports` (#11320) (Ulrich Stark) - b53b053 linter: Simplify accessing span of NameSpan (#11305) (Ulrich Stark) - 4bc2650 linter: Improve `eslint/no-void` (#11285) (shulaoda) ### Styling - 49b664c linter: Remove needless newline in `declare_oxc_lint` (#11400) (camc314) ### Testing - c4f64aa linter: Explicitly disable correctness for clarity (#11327) (camc314) - a404b2c linter: `eslint/no-duplicate-imports` shouldn't report the same span (#11324) (Ulrich Stark) Co-authored-by: camc314 <[email protected]>

github-actions bot added A-linter Area - Linter C-bug Category - Bug labels May 25, 2025

This was referenced May 25, 2025

perf(linter/no-unused-vars): simplify checking self call usage #11281

Merged

refactor(ast): remove AstKind::get_container_scope_id #11282

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Dunqing force-pushed the 05-25-fix_linter_no-unused-vars_panic_when_variable_is_redeclared_as_function_in_same_scope branch from 9e612d4 to c69afcd Compare May 25, 2025 15:29

Dunqing mentioned this pull request May 25, 2025

fix(semantic): update symbol_declarations when a function is found after a var #11234

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Dunqing marked this pull request as ready for review May 25, 2025 15:37

Copilot AI review requested due to automatic review settings May 25, 2025 15:37

Dunqing requested a review from camc314 as a code owner May 25, 2025 15:37

Copilot AI reviewed May 25, 2025

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crates/oxc_linter/src/rules/eslint/no_unused_vars/usage.rs Show resolved Hide resolved

Dunqing force-pushed the 05-25-fix_linter_no-unused-vars_panic_when_variable_is_redeclared_as_function_in_same_scope branch from c69afcd to 21d06cf Compare May 25, 2025 16:07

camc314 added the 0-merge Merge with Graphite Merge Queue label May 25, 2025

graphite-app bot force-pushed the 05-25-fix_linter_no-unused-vars_panic_when_variable_is_redeclared_as_function_in_same_scope branch from 21d06cf to 19772e5 Compare May 25, 2025 16:39

graphite-app bot merged commit 19772e5 into main May 25, 2025
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graphite-app bot removed the 0-merge Merge with Graphite Merge Queue label May 25, 2025

graphite-app bot deleted the 05-25-fix_linter_no-unused-vars_panic_when_variable_is_redeclared_as_function_in_same_scope branch May 25, 2025 16:42

oxc-bot mentioned this pull request May 30, 2025

release(oxlint): v0.17.0 #11402

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fix(linter/no-unused-vars): panic when variable is redeclared as function in same scope #11280

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