Fix `property-no-unknown` false positives for `corner-shape` by jeddy3 · Pull Request #9099 · stylelint/stylelint

jeddy3 · 2026-02-20T17:12:41Z

Which issue, if any, is this issue related to?

Is there anything in the PR that needs further explanation?

We try to avoid false positives, as they're more disruptive to our users than false negatives. Now that the known-css-properties package is getting out of date, we want to avoid maintaining our own reference of new properties by using the csstree lexer.

There are a number of historic properties that differ.

acelerator
additive-symbols
alt
animation-trigger-behavior
animation-trigger-exit-range
animation-trigger-exit-range-end
animation-trigger-exit-range-start
animation-trigger-range
animation-trigger-range-end
animation-trigger-range-start
animation-trigger-timeline
app-region
ascent-override
audio-level
base-palette
buffered-rendering
chains
color-profile
color-rendering
column-progression
column-rule-outset
descent-override
display-align
elevation
enable-background
epub-caption-side
epub-hyphens
epub-text-combine
epub-text-emphasis
epub-text-emphasis-color
epub-text-emphasis-style
epub-text-orientation
epub-text-transform
epub-word-break
epub-writing-mode
fallback
flow
font-display
inherits
initial-value
input-format
inset-area
item-slack
layout-flow
layout-grid
layout-grid-char
layout-grid-line
layout-grid-mode
layout-grid-type
line-gap-override
line-increment
marker-knockout-left
marker-knockout-right
marker-offset
marker-pattern
marker-segment
marks
mask-position-x
mask-position-y
mask-source-type
max-zoom
min-zoom
motion
motion-offset
motion-path
motion-rotation
nav-down
nav-index
nav-left
nav-right
nav-up
navigation
negative
offset-block-end
offset-block-start
offset-inline-end
offset-inline-start
offset-rotation
orientation
override-colors
pad
page-orientation
pen-action
perspective-origin-x
perspective-origin-y
pitch
pitch-range
play-during
position-try-options
prefix
property-name
range
richness
row-rule-outset
rule-outset
rule-paint-order
running
scroll-snap-margin
scroll-snap-margin-bottom
scroll-snap-margin-left
scroll-snap-margin-right
scroll-snap-margin-top
scroll-start-target
scrollbar-arrow-color
scrollbar-base-color
scrollbar-dark-shadow-color
scrollbar-darkshadow-color
scrollbar-face-color
scrollbar-highlight-color
scrollbar-shadow-color
scrollbar-track-color
scrollbar3d-light-color
scrollbar3dlight-color
size
size-adjust
snap-height
solid-color
solid-opacity
speak-header
speak-numeral
speak-punctuation
speech-rate
stress
suffix
supported-color-schemes
symbols
syntax
system
text-decoration-blink
text-decoration-line-through
text-decoration-none
text-decoration-overline
text-decoration-skip-inset
text-decoration-trim
text-decoration-underline
text-justify-trim
text-kashida
text-kashida-space
text-line-through
text-line-through-color
text-line-through-mode
text-line-through-style
text-line-through-width
text-overline
text-overline-color
text-overline-mode
text-overline-style
text-overline-width
text-underline
text-underline-color
text-underline-mode
text-underline-style
text-underline-width
touch-action-delay
transform-origin-x
transform-origin-y
transform-origin-z
types
uc-alt-skin
uc-skin
user-zoom
viewport-fill
viewport-fill-opacity
viewport-fit
volume

I've added these to our reference to avoid regressions.

The change introduces false negatives, such as for -moz-align-self, but this is fine, as we typically favour false negatives over positives.

No change in performance as getProperty is quick:

# main
Warnings: 0
Mean: 99.86150898039216 ms
Deviation: 16.122225718391842 ms

# this branch
Warnings: 0
Mean: 97.8256785769231 ms
Deviation: 15.598629079995217 ms

…rs and `corner-shape`

changeset-bot · 2026-02-20T17:12:45Z

🦋 Changeset detected

Latest commit: 75f24e3

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

This PR includes changesets to release 1 package

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github-actions · 2026-02-20T17:14:52Z

This PR is packaged and the instant preview is available (75f24e3). View the demo website.

Install it locally:

npm i -D https://pkg.pr.new/stylelint@75f24e3

lib/reference/properties.mjs

jeddy3 · 2026-02-21T11:28:36Z

What's even weirder is that it also affects a non-prefixed one. i.e. accelerator

Typo in the Set. I've pushed a commit to fix.

Demo with every property from the package looks clean, so I think no regressions.

resolved

lib/rules/property-no-unknown/README.md

Mouvedia · 2026-02-21T23:40:51Z

Looking at #8155 and #8203, we might have to remove the descriptors from the previouslyKnownProperties set, right?
e.g. syntax

If we do let's do it in a separate PR.

romainmenke

Thank you. LGTM 👍

Nice that the rule has very comparable performance :)

Mister-Hope · 2026-02-26T01:49:39Z

@jeddy3 Can you check #9115? We are meeting issues when upgrading to 17.4.0 from 17.2.0

@theacrat

| datasource | package | from | to | | ---------- | --------- | ------ | ------ | | npm | stylelint | 17.3.0 | 17.4.0 | ## [v17.4.0](https://github.com/stylelint/stylelint/blob/HEAD/CHANGELOG.md#1740---2026-02-25) It adds 2 options to the rules and fixes 7 bugs. - Added: `ignoreAtRules: []` to `at-rule-no-vendor-prefix` ([#9096](stylelint/stylelint#9096)) ([@theacrat](https://github.com/theacrat)). - Added: `ignoreMediaFeatureNames: []` to `media-feature-name-no-vendor-prefix` ([#9097](stylelint/stylelint#9097)) ([@theacrat](https://github.com/theacrat)). - Fixed: performance of selector cloning rules ([#9089](stylelint/stylelint#9089)) ([@jeddy3](https://github.com/jeddy3)). - Fixed: `*-empty-line-before` performance ([#9092](stylelint/stylelint#9092)) ([@jeddy3](https://github.com/jeddy3)). - Fixed: `declaration-property-value-no-unknown` performance ([#9090](stylelint/stylelint#9090)) ([@jeddy3](https://github.com/jeddy3)). - Fixed: `no-irregular-whitespace` performance ([#9091](stylelint/stylelint#9091)) ([@jeddy3](https://github.com/jeddy3)). - Fixed: `property-no-unknown` false negatives for at-rule descriptors ([#9109](stylelint/stylelint#9109)) ([@jeddy3](https://github.com/jeddy3)). - Fixed: `property-no-unknown` false positives for `corner-shape` ([#9099](stylelint/stylelint#9099)) ([@jeddy3](https://github.com/jeddy3)). - Fixed: `property-no-unknown` false positives for double-slashed properties ([#9099](stylelint/stylelint#9099)) ([@jeddy3](https://github.com/jeddy3)).

@theacrat

| datasource | package | from | to | | ---------- | --------- | ------ | ------ | | npm | stylelint | 17.3.0 | 17.4.0 | ## [v17.4.0](https://github.com/stylelint/stylelint/blob/HEAD/CHANGELOG.md#1740---2026-02-25) It adds 2 options to the rules and fixes 7 bugs. - Added: `ignoreAtRules: []` to `at-rule-no-vendor-prefix` ([#9096](stylelint/stylelint#9096)) ([@theacrat](https://github.com/theacrat)). - Added: `ignoreMediaFeatureNames: []` to `media-feature-name-no-vendor-prefix` ([#9097](stylelint/stylelint#9097)) ([@theacrat](https://github.com/theacrat)). - Fixed: performance of selector cloning rules ([#9089](stylelint/stylelint#9089)) ([@jeddy3](https://github.com/jeddy3)). - Fixed: `*-empty-line-before` performance ([#9092](stylelint/stylelint#9092)) ([@jeddy3](https://github.com/jeddy3)). - Fixed: `declaration-property-value-no-unknown` performance ([#9090](stylelint/stylelint#9090)) ([@jeddy3](https://github.com/jeddy3)). - Fixed: `no-irregular-whitespace` performance ([#9091](stylelint/stylelint#9091)) ([@jeddy3](https://github.com/jeddy3)). - Fixed: `property-no-unknown` false negatives for at-rule descriptors ([#9109](stylelint/stylelint#9109)) ([@jeddy3](https://github.com/jeddy3)). - Fixed: `property-no-unknown` false positives for `corner-shape` ([#9099](stylelint/stylelint#9099)) ([@jeddy3](https://github.com/jeddy3)). - Fixed: `property-no-unknown` false positives for double-slashed properties ([#9099](stylelint/stylelint#9099)) ([@jeddy3](https://github.com/jeddy3)).

jeddy3 added 4 commits February 20, 2026 16:34

Fix property-no-unknown false negatives and positives for descripto…

0e0982d

…rs and `corner-shape`

Document consistent description with other *-no-unknown rules

2d5e240

Document consistent extending syntax

22ede53

Add previously known properties

1394aaf

jeddy3 requested a review from a team as a code owner February 20, 2026 17:12

Changeset

ebcc95e

Add corner-shape testcase

aa486f8

Mouvedia reviewed Feb 20, 2026

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jeddy3 added 2 commits February 21, 2026 11:17

Fix for prefixed

0a0ca57

Fix accelerator typo

96a4fb3

Mouvedia reviewed Feb 21, 2026

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lib/rules/property-no-unknown/README.md Show resolved Hide resolved

Document in README

75f24e3

jeddy3 mentioned this pull request Feb 24, 2026

Release 17.4.0 #9098

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romainmenke approved these changes Feb 25, 2026

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jeddy3 merged commit 83cfd65 into main Feb 25, 2026
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jeddy3 deleted the fix-property-no-unknown branch February 25, 2026 10:18

jeddy3 mentioned this pull request Feb 25, 2026

Fix property-no-unknown false negatives for at-rule descriptors #9109

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Mister-Hope mentioned this pull request Feb 26, 2026

Fix property-no-unknown false positive for font-display #9115

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