Fix `declaration-block-no-redundant-longhand-properties` false negatives for shorthand-then-longhand #8892

nathannewyen · 2025-12-05T07:42:22Z

Summary

This PR detects redundant longhand properties when they follow a shorthand property with the same value.

Before

a {
  background: red;
  background-color: red; /* No warning - false negative */
}

After

a {
  background: red;
  background-color: red; /* Warning: Unexpected longhand property "background-color" after shorthand property "background" with same value */
}

Changes

Track declared shorthand properties and their values during declaration block traversal
Check if longhand properties have a covering shorthand with the same value
Add new message type redundantLonghand for clear error reporting
Add auto-fix support to remove redundant longhands
Add test cases for both accept (different values) and reject (same values) scenarios

Test Plan

Added accept tests for shorthand + longhand with different values (should pass)
Added reject tests for shorthand + longhand with same values (should warn)
All existing tests pass
Lint and type checks pass

changeset-bot · 2025-12-05T07:42:26Z

🦋 Changeset detected

Latest commit: 0173032

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
stylelint	Minor

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ybiquitous

@nathannewyen Thanks for the pull request.

We've started working on the v17 branch, not main, toward the next major version, so can you please recreate the feature branch from v17 and change the base branch of this PR?

…s for shorthand-then-longhand This commit fixes issue stylelint#8349 by detecting redundant longhand properties when they follow a shorthand property with the same value. For example, the following CSS now triggers a warning: ```css a { background: red; background-color: red; /* Redundant - flagged now */ } ``` Changes: - Add tracking of declared shorthand properties and their values - Check if longhand properties have a covering shorthand with the same value - Add new message type `redundantLonghand` for clear error reporting - Add auto-fix support to remove redundant longhands - Add test cases for both accept and reject scenarios Closes stylelint#8349

nathannewyen · 2025-12-06T01:34:41Z

I just rebased onto v17 and updated the base branch, can you double check?

github-actions · 2025-12-06T02:05:14Z

This PR is packaged and the instant preview is available (68bdba7). View the demo website.

Install it locally:

npm i -D https://pkg.pr.new/stylelint@68bdba7

ybiquitous

Thanks. I've left review comments, so can you address them?

[suggestion] Can you add two examples to the README?

a problem example
a non-problem example

lib/rules/declaration-block-no-redundant-longhand-properties/README.md

lib/rules/declaration-block-no-redundant-longhand-properties/index.mjs

lib/rules/declaration-block-no-redundant-longhand-properties/__tests__/index.mjs

lib/rules/declaration-block-no-redundant-longhand-properties/index.mjs

nathannewyen · 2025-12-06T05:50:56Z

Hi sorry for taking a bit long, can you check again. Thanks alot!

ybiquitous

Thank you. The implementation code looks good. 👍🏼

Additionally, can you fix the test failures and take a look at my reviews on the doc and test?

lib/rules/declaration-block-no-redundant-longhand-properties/README.md

lib/rules/declaration-block-no-redundant-longhand-properties/__tests__/index.mjs

…EADME.md Co-authored-by: Masafumi Koba <473530+ybiquitous@users.noreply.github.com>

Update test expectations to match actual values from the new redundant longhand detection feature: - Add fix objects to warnings for multiple redundant longhands - Update column positions (35->36, 47->48) for margin-right - Update fix range from [34, 54] to [35, 54]

ybiquitous

Thanks, LGTM 👍🏼
(I additionally pushed d788ec6 and 0173032 for minor fixes in the doc and test)

Just in case, let's wait for one approval since this PR will produce more lint problems.

jeddy3

@nathannewyen LGTM, thank you!

@ybiquitous Thank you for reviewing and helping shape the PR 🙇

Mouvedia · 2025-12-09T20:38:05Z

We've started working on the v17 branch, not main, toward the next major version, so…

Shouldn't the fixes go to main for the time being?
i.e. only the breaking changes would be on v17

@jeddy3

| datasource | package | from | to | | ---------- | --------- | ------- | ------ | | npm | stylelint | 16.26.1 | 17.0.0 | ## [v17.0.0](https://github.com/stylelint/stylelint/blob/HEAD/CHANGELOG.md#1700---2026-01-15) It contains 14 breaking changes, which we've detailed in the [migrating to `17.0.0` guide](docs/migration-guide/to-17.md). Additionally, it adds 3 options to the rules and fixes 9 bugs. We've also released compatible versions of our [shared config](https://www.npmjs.com/package/stylelint-config-standard), [Visual Studio Code extension](https://marketplace.visualstudio.com/items?itemName=stylelint.vscode-stylelint), [Node.js Rule Tester](https://www.npmjs.com/package/stylelint-test-rule-node) and [Jest preset](https://www.npmjs.com/package/jest-preset-stylelint). - Removed: CommonJS Node.js API ([#8859](stylelint/stylelint#8859)) ([@jeddy3](https://github.com/jeddy3)). - Removed: `output` property in the Node.js API returned resolved object ([#8878](stylelint/stylelint#8878)) ([@jeddy3](https://github.com/jeddy3)). - Removed: support for Node.js less than 20.19.0 ([#8867](stylelint/stylelint#8867)) ([@jeddy3](https://github.com/jeddy3)). - Removed: GitHub formatter ([#8888](stylelint/stylelint#8888)) ([@jeddy3](https://github.com/jeddy3)). - Removed: `resolveNestedSelectors` option from `selector-class-pattern` ([#8931](stylelint/stylelint#8931)) ([@jeddy3](https://github.com/jeddy3)). - Removed: `checkContextFunctionalPseudoClasses` option from `selector-max-id` ([#8913](stylelint/stylelint#8913)) ([@jeddy3](https://github.com/jeddy3)). - Changed: default `fix` mode to `strict` ([#8889](stylelint/stylelint#8889)) ([@jeddy3](https://github.com/jeddy3)). - Changed: `report` to be consistent and predictable in how it handles the provided position arguments ([#8217](stylelint/stylelint#8217)) ([@romainmenke](https://github.com/romainmenke)). - Changed: `selector-max-*` syntax rules for standard CSS nesting and modern functional pseudo-classes ([#8913](stylelint/stylelint#8913)) ([@jeddy3](https://github.com/jeddy3)). - Changed: `*-specificity` semantic rules for standard CSS nesting ([#8913](stylelint/stylelint#8913)) ([@jeddy3](https://github.com/jeddy3)). - Changed: `no-duplicate-selectors` and `selector-no-qualifying-type` for standard CSS nesting ([#8913](stylelint/stylelint#8913)) ([@jeddy3](https://github.com/jeddy3)). - Changed: `*-list` rules to have consistent behaviour for vendor prefixes and case ([#8912](stylelint/stylelint#8912)) ([@jeddy3](https://github.com/jeddy3)). - Changed: `*-no-vendor-prefix` rules to have consistent behaviour for their `ignore*: []` secondary options ([#8924](stylelint/stylelint#8924)) ([@jeddy3](https://github.com/jeddy3)). - Changed: `declaration-property-max-values` rule to have consistent behaviour for vendor prefixes ([#8926](stylelint/stylelint#8926)) ([@jeddy3](https://github.com/jeddy3)). - Added: `except: ["after-block"]` to `custom-property-empty-line-before` ([#8921](stylelint/stylelint#8921)) ([@kovsu](https://github.com/kovsu)). - Added: `except: ["after-block"]` to `declaration-empty-line-before` ([#8910](stylelint/stylelint#8910)) ([@kovsu](https://github.com/kovsu)). - Added: `ignoreSelectors: []` to `no-duplicate-selectors` ([#8883](stylelint/stylelint#8883)) ([@kovsu](https://github.com/kovsu)). - Fixed: Windows drive letter casing inconsistencies when matching patterns against file paths ([#8941](stylelint/stylelint#8941)) ([@adalinesimonian](https://github.com/adalinesimonian)). - Fixed: CLI help to include TypeScript config files ([#8908](stylelint/stylelint#8908)) ([@kovsu](https://github.com/kovsu)). - Fixed: `at-rule-descriptor-no-unknown` false positives for declarations within feature-value-blocks ([#8868](stylelint/stylelint#8868)) ([@kovsu](https://github.com/kovsu)). - Fixed: `declaration-block-no-redundant-longhand-properties` false negatives for short and long combinations ([#8892](stylelint/stylelint#8892)) ([@nathannewyen](https://github.com/nathannewyen)). - Fixed: `media-feature-name-no-unknown` false positives for namespaced dollar variables and range context queries ([#8890](stylelint/stylelint#8890)) ([@kovsu](https://github.com/kovsu)). - Fixed: `nesting-selector-no-missing-scoping-root` false positives for CSS-in-JS ([#8905](stylelint/stylelint#8905)) ([@kovsu](https://github.com/kovsu)). - Fixed: `no-invalid-position-declaration` false negatives for embedded blocks ([#8907](stylelint/stylelint#8907)) ([@kovsu](https://github.com/kovsu)). - Fixed: `selector-no-qualifying-type` false negatives for `:is/where()` ([#8940](stylelint/stylelint#8940)) ([@romainmenke](https://github.com/romainmenke)). - Fixed: `selector-type-no-unknown` false positives for MathML 4 tags ([#8874](stylelint/stylelint#8874)) ([@jeddy3](https://github.com/jeddy3)).

nathannewyen force-pushed the fix/redundant-longhand-after-shorthand branch from 9306b73 to 922a26a Compare December 5, 2025 07:45

ybiquitous requested changes Dec 6, 2025

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nathannewyen force-pushed the fix/redundant-longhand-after-shorthand branch from 922a26a to a5ba767 Compare December 6, 2025 01:31

nathannewyen requested a review from a team as a code owner December 6, 2025 01:31

nathannewyen force-pushed the fix/redundant-longhand-after-shorthand branch from a5ba767 to 68bdba7 Compare December 6, 2025 01:32

nathannewyen changed the base branch from main to v17 December 6, 2025 01:32

Add changelog

01786e9

ybiquitous requested changes Dec 6, 2025

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nathannewyen added 3 commits December 5, 2025 22:15

Remove verbose comments from README examples and code

60dcff4

Rename redundantLonghand to unexpectedLonghand for consistency

6077f2c

Address review feedback: refactor code and update tests

721cf6d

ybiquitous requested changes Dec 6, 2025

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nathannewyen and others added 5 commits December 6, 2025 13:12

Update lib/rules/declaration-block-no-redundant-longhand-properties/R…

4312d6d

…EADME.md Co-authored-by: Masafumi Koba <473530+ybiquitous@users.noreply.github.com>

Update lib/rules/declaration-block-no-redundant-longhand-properties/R…

70b1726

…EADME.md Co-authored-by: Masafumi Koba <473530+ybiquitous@users.noreply.github.com>

Add test cases for ignoreShorthands and ignoreLonghands options

49c8b6d

fix: correct fix range for margin-left warning [24, 42]

e34ae6e

nathannewyen requested a review from ybiquitous December 7, 2025 21:40

nathannewyen and others added 4 commits December 7, 2025 16:40

Merge branch 'v17' into fix/redundant-longhand-after-shorthand

9023b41

fix: remove fix object from margin-right warning (should be undefined)

059a01b

Move new example to last

d788ec6

Merge test cases into one testRule

0173032

ybiquitous approved these changes Dec 8, 2025

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jeddy3 approved these changes Dec 9, 2025

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jeddy3 merged commit 3e18363 into stylelint:v17 Dec 9, 2025
14 checks passed

jeddy3 mentioned this pull request Dec 9, 2025

Fix declaration-block-no-redundant-longhand-properties false negatives for short and long combinations #8349

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Fix declaration-block-no-redundant-longhand-properties false negatives for shorthand-then-longhand #8892

Fix declaration-block-no-redundant-longhand-properties false negatives for shorthand-then-longhand #8892

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Fix `declaration-block-no-redundant-longhand-properties` false negatives for shorthand-then-longhand #8892

Fix `declaration-block-no-redundant-longhand-properties` false negatives for shorthand-then-longhand #8892

nathannewyen commented Dec 5, 2025 •

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