Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 4fc65915b5cfbd4fe0525657e66242f86ea87fbb
https://github.com/WebKit/WebKit/commit/4fc65915b5cfbd4fe0525657e66242f86ea87fbb
Author: Ahmad Saleem <[email protected]>
Date: 2026-05-25 (Mon, 25 May 2026)
Changed paths:
M LayoutTests/TestExpectations
M Source/WebCore/rendering/RenderBlock.cpp
Log Message:
-----------
Fieldset border painted behind legend when legend overlaps non-block-start
border via negative margin
https://bugs.webkit.org/show_bug.cgi?id=189617
rdar://174185071
Reviewed by Alan Baradlay.
This patch aligns WebKit with Gecko / Firefox and Blink / Chromium.
Per spec [1], the fieldset border should not be painted behind the rendered
legend. When the CSS block-start border is zero (e.g. border:none;
border-left:100px solid red), paintRectToClipOutFromBorder() produced an
empty clip rect since it used borderBefore as the clip extent. This meant
a legend overlapping a non-block-start border via negative margin did not
clip that border.
When borderBefore is zero, use the legend's layout box (mapped into
paint-relative coordinates) as the clip rect instead. This only activates
when there is no block-start border, so normal fieldsets with a block-start
border gap are completely unaffected.
[1]
https://html.spec.whatwg.org/multipage/rendering.html#the-fieldset-and-legend-elements
* LayoutTests/TestExpectations: Progression
* Source/WebCore/rendering/RenderBlock.cpp:
(WebCore::RenderBlock::paintRectToClipOutFromBorder):
Canonical link: https://commits.webkit.org/313863@main
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