243940 2022-08-15 09:32:41 -0700 REGRESSION(252825@main): wpt /css/CSS2/visudet/inline-block-baseline-011.xht & inline-block-baseline-014.xht 2025-11-01 16:00:40 -0700 1 1 1 Unclassified WebKit Layout and Rendering WebKit Nightly Build Unspecified Unspecified RESOLVED CONFIGURATION CHANGED https://bugs.webkit.org/show_bug.cgi?id=243197 https://bugs.webkit.org/show_bug.cgi?id=209735 https://bugs.webkit.org/show_bug.cgi?id=261212 http://wpt.live/css/CSS2/visudet/inline-block-baseline-011.xht InRadar, WPTImpact P2 Normal --- 1 gsnedders webkit-unassigned ahmad.saleem792 bfulgham simon.fraser webkit-bug-importer zalan oldest_to_newest 1891348 0 gsnedders 2022-08-15 09:32:41 -0700 wpt.fyi: https://wpt.fyi/results/css/CSS2/visudet?label=master&label=experimental&product=safari-150%20preview&product=safari-151%20preview&view=subtest&q=is%3Adifferent 1891349 1 webkit-bug-importer 2022-08-15 09:33:04 -0700 <rdar://problem/98673438> 1891566 2 zalan 2022-08-15 20:33:05 -0700 This is about integral based alignment vs. non-integral based box model values e.g: vertical-align: -0.5px; -> turns into 0px margin-bottom: 0.5px; -> stays at 0.5px these tests trigger this mismatch through the combination of 'font-size: 15px' and 'align/margin -> 0.5em'. Legacy line layout is historically integral based, while IFC is not, currently it is forced to match legacy behavior through explicit flooring/ceiling of certain values. 1891669 3 zalan 2022-08-16 08:32:05 -0700 This is actually broken (and probably has been broken forever) with legacy line layout and now IFC just matches this broken behavior. :( 1891679 4 zalan 2022-08-16 09:11:49 -0700 Not forcing integral rounding fixes the issue (see below). So while 252825@main looks like the regression point, it never worked in IFC either, it was just covered by the directional rounding bug -which got corrected in 252825@main. The actual cause of this bug is the explicit rounding we need to do in IFC to match legacy line layout behavior. diff --git a/Source/WebCore/layout/formattingContexts/inline/InlineLevelBox.h b/Source/WebCore/layout/formattingContexts/inline/InlineLevelBox.h index 0ac8876b9a15..16420dd6b53c 100644 --- a/Source/WebCore/layout/formattingContexts/inline/InlineLevelBox.h +++ b/Source/WebCore/layout/formattingContexts/inline/InlineLevelBox.h @@ -123,11 +123,11 @@ private: // FIXME: Remove legacy rounding. void setLogicalWidth(InlineLayoutUnit logicalWidth) { m_logicalRect.setWidth(logicalWidth); } - void setLogicalHeight(InlineLayoutUnit logicalHeight) { m_logicalRect.setHeight(roundToInt(logicalHeight)); } - void setLogicalTop(InlineLayoutUnit logicalTop) { m_logicalRect.setTop(logicalTop >= 0 ? roundToInt(logicalTop) : -roundToInt(-logicalTop)); } - void setAscent(InlineLayoutUnit ascent) { m_ascent = roundToInt(ascent); } - void setDescent(InlineLayoutUnit descent) { m_descent = roundToInt(descent); } - void setLayoutBounds(const LayoutBounds& layoutBounds) { m_layoutBounds = { InlineLayoutUnit(roundToInt(layoutBounds.ascent)), InlineLayoutUnit(roundToInt(layoutBounds.descent)) }; } + void setLogicalHeight(InlineLayoutUnit logicalHeight) { m_logicalRect.setHeight(logicalHeight); } + void setLogicalTop(InlineLayoutUnit logicalTop) { m_logicalRect.setTop(logicalTop); } + void setAscent(InlineLayoutUnit ascent) { m_ascent = ascent; } + void setDescent(InlineLayoutUnit descent) { m_descent = descent; } + void setLayoutBounds(const LayoutBounds& layoutBounds) { m_layoutBounds = { InlineLayoutUnit(layoutBounds.ascent), InlineLayoutUnit(layoutBounds.descent) }; } void setIsFirstBox() { m_isFirstWithinLayoutBox = true; } void setIsLastBox() { m_isLastWithinLayoutBox = true; } 2155760 5 ahmad.saleem792 2025-11-01 16:00:40 -0700 We are passing these tests - https://wpt.fyi/results/css/CSS2/visudet?label=master&label=experimental&aligned&q=inline-block-baseline-01 Since April 2025. So marking this as `RESOLVED Configuration Changed`.