feat(eslint-plugin): [no-unused-vars] add a default-off option to autofix remove unused imports #11243

nayounsang · 2025-05-23T15:53:14Z

PR Checklist

Addresses an existing open issue: fixes Enhancement: [no-unused-vars] add a default-off option to autofix remove unused imports #11223
That issue was marked as accepting prs
Steps in Contributing were taken

Overview

Auto fix & suggest unused import statements

Test cases that correspond to the issue can be fixed
add option: enableAutofixRemoval.imports: boolean , not enable default

examples

import Unused1 from 'foo';
import Unused2, { Used } from 'bar';
export { Used };

import { Used } from 'bar';
export { Used };

// -------------------
import { Unused1 } from 'foo';
import Used1, { Unused2 } from 'bar';
import { Used2, Unused3 } from 'baz';
import Used3, { Unused4, Used4 } from 'foobar';
export { Used1, Used2, Used3, Used4 };

import Used1 from 'bar';
import { Used2 } from 'baz';
import Used3, { Used4 } from 'foobar';
export { Used1, Used2, Used3, Used4 };

// -----------------
import { /* cmt */ Unused1, Used1 } from 'foo';
export { Used1 };

import { /* cmt */ Used1 } from 'foo';
export { Used1 };

// ------------------
import type { UnusedType } from 'foo';
import { Used1, Unused1 } from 'foo';
export { Used1 };

import { Used1 } from 'foo';
export { Used1 };

// -----------------
import { Unused1 as u1, Used1 as u2 } from 'foo';
export { u2 };

import { Used1 as u2 } from 'foo';
export { u2 };

typescript-eslint · 2025-05-23T15:53:17Z

Thanks for the PR, @nayounsang!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

Thanks again!

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nx-cloud · 2025-05-23T15:54:12Z

View your CI Pipeline Execution ↗ for commit eb3fd2b

Command	Status	Duration	Result
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`nx run-many -t lint`	✅ Succeeded	3m 11s	View ↗
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☁️ Nx Cloud last updated this comment at 2025-07-14 06:53:42 UTC

nayounsang · 2025-05-23T16:07:04Z

Wow, when adding a new feature, a follow-up development is needed. I'll work on it tomorrow.

codecov · 2025-05-24T13:13:55Z

Codecov Report

Attention: Patch coverage is 94.52055% with 4 lines in your changes missing coverage. Please review.

Project coverage is 90.85%. Comparing base (16c344e) to head (eb3fd2b).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/eslint-plugin/src/rules/no-unused-vars.ts	94.52%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #11243   +/-   ##
=======================================
  Coverage   90.85%   90.85%           
=======================================
  Files         501      501           
  Lines       50987    51060   +73     
  Branches     8410     8430   +20     
=======================================
+ Hits        46324    46393   +69     
- Misses       4648     4652    +4     
  Partials       15       15

Flag	Coverage Δ
unittest	`90.85% <94.52%> (+<0.01%)`	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
packages/eslint-plugin/src/rules/no-unused-vars.ts	`99.41% <94.52%> (-0.59%)`	⬇️

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

packages/eslint-plugin/tests/rules/no-unused-vars/no-unused-vars.test.ts

This reverts commit e5394b2.

…ture

kirkwaiblinger

A great start!

I'm leaving a bit of a drive-by review since I see that there are several major TODOs in the code that need to get resolved. Feel free to reach out if you're looking for help with those! In the meantime, I'm going to leave a Changes Requested review so that this isn't in our ready-to-review queue.

Thanks!

kirkwaiblinger · 2025-06-06T00:12:48Z

packages/eslint-plugin/src/rules/no-unused-vars.ts

+
+                    const source = context.sourceCode;
+                    const node = def.node;
+                    const decl = node.parent as TSESTree.ImportDeclaration;


I think that this will be unsound for import = require-style imports, for example

import x = require('foo')

Let's be sure to include some test coverage with that style of import.

Oh, nice catch. This is TSImportEqualsDeclaration type.
I test with this code:

{ code: ` import x = require('foo'); import y = require('bar'); export { y }; `, errors: [{ messageId: 'unusedVar' }], options: [{ enableAutofixRemoval: { imports: true } }], output: ` import y = require('bar'); export { y }; `, }

In the existing logic, an error occurs and a more accurate logic is used rather than type casting.
related commit: 11ac4fa

kirkwaiblinger · 2025-06-06T00:22:58Z

packages/eslint-plugin/src/rules/no-unused-vars.ts

@@ -687,6 +708,80 @@ export default createRule<Options, MessageIds>({
              data: unusedVar.references.some(ref => ref.isWrite())
                ? getAssignedMessageData(unusedVar)
                : getDefinedMessageData(unusedVar),
+              fix: options.enableAutofixRemoval?.imports


This seems useful as a suggestion, even if the autofix option is disabled. Consider using getFixOrSuggest to conditionally provide this fix as a suggestion?

typescript-eslint/packages/eslint-plugin/src/util/getFixOrSuggest.ts

Lines 3 to 21 in 5b2ebcd

export function getFixOrSuggest<MessageId extends string>({

fixOrSuggest,

suggestion,

}: {

fixOrSuggest: 'fix' | 'none' | 'suggest';

suggestion: TSESLint.SuggestionReportDescriptor<MessageId>;

}):

| { fix: TSESLint.ReportFixFunction }

| { suggest: TSESLint.SuggestionReportDescriptor<MessageId>[] }

| undefined {

switch (fixOrSuggest) {

case 'fix':

return { fix: suggestion.fix };

case 'none':

return undefined;

case 'suggest':

return { suggest: [suggestion] };

}

}

Good idea. However, it would be better to provide suggestions to existing test cases and then resolve this comment before processing.

kirkwaiblinger · 2025-06-06T00:27:21Z

packages/eslint-plugin/src/rules/no-unused-vars.ts

+                    if (decl.specifiers.length === 1) {
+                      return fixer.removeRange([
+                        decl.range[0],
+                        decl.range[1] + 1, // +1 to include "\n"


to include "\n"

Why do we want to do this exactly? This causes a bug with this technically valid code (please include as a test case - hint, you'll need to use noFormat):

import x from 'foo';import y from 'bar'

My instinct is to say we're better off just leaving a blank line and letting the user decide how to format it afterwards (whether by hand or with prettier or similar).

we're better off just leaving a blank line and letting the user decide how to format it afterwards (whether by hand or with prettier or similar).

Wow, that's right. That should have been it. Plus, it lowers the difficulty of solving the problem and the code becomes simpler.
related commit: 9f76441 & 633d2c8

Add new message: unusedVarSuggestion. However, I'm concerned about the proposed message: Remove unused variable.. Any thoughts?

related commit: 2c8b740 & 9a15d49

packages/eslint-plugin/tests/rules/no-unused-vars/no-unused-vars.test.ts

nayounsang · 2025-06-11T12:31:16Z

@kirkwaiblinger Hi. I committed my code about your review and TODOs! Please make sure I'm on the right track.
The problem to be solved now is: Problem with unformatted code. (Based on 0-index) Odd specifiers are not deleted.
Um... I run console.log in the local and see results of the ranges need to be deleted, and in this case, the range to delete did not conflict! I don't know why.

// test case
import {A,B,C,D,E,F,G,Used1,H,I,J,K} from 'foo';
export {Used1};

// expect
import {Used1} from 'foo';
export {Used1};

// received
import {B,D,F,Used1,I,K} from 'foo'
export {Used1};

How can I solve this problem? My idea is to merge the contiguous segments and remove multiple specifiers at once.
For ex

import {A,B,C,D,E,F,G,Used1,H,I,J,K} from 'foo';  // ->
import {Used1,H,I,J,K} from 'foo'; // ->
import {Used1} from 'foo';

nayounsang

I'm going to try something different than my previous commit.
This is reason & plan:
1. Fixing multiple specifers at once is confusing and incompatible with the existing way of reporting.
2. Test cases that test for multiple types of imports are more suitable for Unit testing.

Done, I apologize to the reviewer for the change, but I think this is the right direction.

nayounsang added 2 commits May 24, 2025 00:49

test: add testcase

e5394b2

feat: test successful logic

e339973

nayounsang marked this pull request as draft May 23, 2025 15:53

chore: generate schema

7fc5d69

nayounsang commented May 24, 2025

View reviewed changes

packages/eslint-plugin/tests/rules/no-unused-vars/no-unused-vars.test.ts Outdated Show resolved Hide resolved

nayounsang and others added 9 commits June 3, 2025 17:42

chore: Revert "test: add testcase"

7b06e7c

This reverts commit e5394b2.

chore: remove uninteded code changes

a2dce5f

refactor: simplify conditional statements to increase converage

855acdf

test: add testacase autofixer should do nothing in import-autofix fea…

233fb1e

…ture

test: add more testcases

622aaf0

refactor: remove duplicate condition validate

122509f

test: add more test case

556ae92

chore: logic that is currently difficult to implement is left as TODO

6d35a71

Merge branch 'main' into auto-unused

440d112

nayounsang marked this pull request as ready for review June 5, 2025 06:13

chore: add line for test category

d9f1609

kirkwaiblinger requested changes Jun 6, 2025

View reviewed changes

kirkwaiblinger added the awaiting response Issues waiting for a reply from the OP or another party label Jun 6, 2025

nayounsang added 3 commits June 6, 2025 18:20

fix: remove type casting and support TSImportEqulasDeclaration node

11ac4fa

test: simplify test case with noFormat

633d2c8

fix: remove format-related logic

9f76441

nayounsang commented Jun 6, 2025

View reviewed changes

packages/eslint-plugin/tests/rules/no-unused-vars/no-unused-vars.test.ts Outdated Show resolved Hide resolved

nayounsang and others added 3 commits June 8, 2025 21:53

Merge branch 'main' into auto-unused

99699fc

feat: add suggestion for enableAUtofixRemoval

2c8b740

test: add suggestion effected by import statement

9a15d49

nayounsang and others added 5 commits June 8, 2025 23:43

test: add suggestion for no-unused-vars-eslint test

6de9050

feat: remove all unused specifers at once if no used specifers in decl

a177e5c

test: add test

1a05465

Merge branch 'main' into auto-unused

5662583

chore: resolve real conflict

90c2d9a

nayounsang commented Jul 5, 2025

View reviewed changes

Merge branch 'main' into auto-unused

80ec92b

bradzacher changed the title ~~feat(eslint-plugin): add a default-off option to autofix remove unused imports~~ feat(eslint-plugin): [no-unused-vars] add a default-off option to autofix remove unused imports Jul 9, 2025

bradzacher removed the awaiting response Issues waiting for a reply from the OP or another party label Jul 13, 2025

nayounsang and others added 2 commits July 14, 2025 14:35

Merge branch 'main' into auto-unused

8759180

fix: simplyfy logic and modify tc to fit unit tests

eb3fd2b

nayounsang requested a review from kirkwaiblinger July 14, 2025 06:53

	export function getFixOrSuggest<MessageId extends string>({
	fixOrSuggest,
	suggestion,
	}: {
	fixOrSuggest: 'fix' \| 'none' \| 'suggest';
	suggestion: TSESLint.SuggestionReportDescriptor<MessageId>;
	}):
	\| { fix: TSESLint.ReportFixFunction }
	\| { suggest: TSESLint.SuggestionReportDescriptor<MessageId>[] }
	\| undefined {
	switch (fixOrSuggest) {
	case 'fix':
	return { fix: suggestion.fix };
	case 'none':
	return undefined;
	case 'suggest':
	return { suggest: [suggestion] };
	}
	}

Uh oh!

feat(eslint-plugin): [no-unused-vars] add a default-off option to autofix remove unused imports #11243

Are you sure you want to change the base?

feat(eslint-plugin): [no-unused-vars] add a default-off option to autofix remove unused imports #11243

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PR Checklist

Overview

Auto fix & suggest unused import statements

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