feat(linter): add rule noRedundantDefaultExport by koshin01 · Pull Request #8931 · biomejs/biome

koshin01 · 2026-02-01T11:42:37Z

Notice: I consulted ChatGPT and Cursor to understand the codebase and review the code I wrote.

Summary

This PR introduces a new lint rule: noRedundantDefaultExport.

Test Plan

Added spec tests under:
- crates/biome_js_analyze/tests/specs/nursery/noRedundantDefaultExport/**
- with corresponding .snap snapshot outputs.

This is my first PR to Biome, so it may not include all necessary changes. If that's the case, I'd appreciate it if you could let me know.

…ning

…ult export names in no_redundant_default_export lint rule

…dantDefaultExport

changeset-bot · 2026-02-01T11:42:41Z

🦋 Changeset detected

Latest commit: b962a1e

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

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

coderabbitai · 2026-02-01T15:07:12Z

Walkthrough

Adds a new JavaScript lint rule noRedundantDefaultExport (registered via declare_lint_rule!) that detects when a module exports the same binding as both a named export and the default export, excluding re-exports. Implements rule logic and helpers, emits diagnostics with source ranges, adds unit tests for valid and invalid cases, introduces NoRedundantDefaultExportOptions, exposes a new rule options module, and adds a changeset for @biomejs/biome.

Suggested reviewers

ematipico
dyc3

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately and concisely describes the main change: adding a new lint rule named noRedundantDefaultExport.
Description check	✅ Passed	The description is relevant and provides context about the change, references the linked issue, and mentions the test plan.
Linked Issues check	✅ Passed	The PR implements the noRedundantDefaultExport rule [`#5885`] that detects when a module exports the same symbol as both default and named export, correctly excluding re-exports.
Out of Scope Changes check	✅ Passed	All changes are directly related to implementing the noRedundantDefaultExport rule, including the rule implementation, test cases, and configuration files.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

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Post copyable unit tests in a comment

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dyc3

Nice first draft!

codspeed-hq · 2026-02-01T18:15:21Z

Merging this PR will not alter performance

✅ 58 untouched benchmarks
⏩ 95 skipped benchmarks¹

_{Comparing koshin01:feat/add_rule_noRedundantDefaultExport (b962a1e) with main (7c96517)}

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. ↩

dyc3

Nicely done! Just needs a tweak to the changeset.

Co-authored-by: Carson McManus <[email protected]>

coderabbitai

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In @.changeset/light-crews-cough.md:
- Line 5: Replace the "<brief explanation>" placeholder with a concise
description of the new nursery rule noRedundantDefaultExport: state that the
rule detects and flags modules that export the same binding as both a named
export and a default export (redundant default exports), and give a short
example or purpose phrase such as "flags when a module exports the same
identifier as both a named export and the default to avoid redundancy." Ensure
the replacement sits inline with the existing sentence so the changelog line
reads naturally.

koshin01 added 13 commits January 3, 2026 00:06

generated template

fab2dd6

Add valid case

79110d1

Enhance noRedundantDefaultExport lint rule by setting severity to War…

3810dc9

…ning

simple rule

5aafb63

Refactor collect_exports function to use TokenText for named and defa…

ae67aad

…ult export names in no_redundant_default_export lint rule

Narrow diagnostic scope

accecb1

Update correct test case

5bbbe4e

add export "default" name test case

0e0baa8

Update file name

424419d

Refactoring

fceb5b7

add snap

cb45dbc

Merge remote-tracking branch 'origin/main' into feat/add_rule_noRedun…

0d168c2

…dantDefaultExport

exec just gen-analyzer

112249d

github-actions Bot added A-Project Area: project A-Linter Area: linter L-JavaScript Language: JavaScript and super languages A-Diagnostic Area: diagnostocis labels Feb 1, 2026

Add change set

2fe8b84

koshin01 marked this pull request as ready for review February 1, 2026 14:57

dyc3 requested changes Feb 1, 2026

View reviewed changes

Comment thread crates/biome_js_analyze/src/lint/nursery/no_redundant_default_export.rs

Comment thread crates/biome_js_analyze/src/lint/nursery/no_redundant_default_export.rs

Comment thread crates/biome_js_analyze/src/lint/nursery/no_redundant_default_export.rs Outdated

koshin01 added 5 commits February 3, 2026 03:01

Moved all helper functions under the impl Rule block

bd323b4

Added sources property

d62cff4

Added how note

79051bd

Combined if statement

9f5cc93

Update snapshots

241fcc1

dyc3 approved these changes Feb 2, 2026

View reviewed changes

Comment thread .changeset/light-crews-cough.md Outdated

Updated light-crews-cough.md

d06df04

Co-authored-by: Carson McManus <[email protected]>

coderabbitai Bot reviewed Feb 2, 2026

View reviewed changes

Comment thread .changeset/light-crews-cough.md Outdated

Added an explanation of the rule to the changset

b962a1e

dyc3 merged commit 4561751 into biomejs:main Feb 2, 2026
20 checks passed

github-actions Bot mentioned this pull request Feb 2, 2026

ci: release #8888

Merged

coderabbitai Bot mentioned this pull request Mar 25, 2026

fix(grit): fix queries for export { $foo } ... #9586

Merged

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feat(linter): add rule noRedundantDefaultExport#8931

feat(linter): add rule noRedundantDefaultExport#8931
dyc3 merged 21 commits intobiomejs:mainfrom
koshin01:feat/add_rule_noRedundantDefaultExport

koshin01 commented Feb 1, 2026 •

edited by dyc3

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koshin01 commented Feb 1, 2026 • edited by dyc3 Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

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🦋 Changeset detected

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Walkthrough

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codspeed-hq Bot commented Feb 1, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Merging this PR will not alter performance

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koshin01 commented Feb 1, 2026 •

edited by dyc3

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