Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: e63622220d8afb3b32fe321feb489fed73b941b9
https://github.com/WebKit/WebKit/commit/e63622220d8afb3b32fe321feb489fed73b941b9
Author: Brandon Stewart <[email protected]>
Date: 2026-02-25 (Wed, 25 Feb 2026)
Changed paths:
A
LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-display-grid-intrinsic-sizing-expected.html
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LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-display-grid-intrinsic-sizing-ref.html
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LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-display-grid-intrinsic-sizing.html
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LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-intrinsic-sizing-expected.html
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LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-intrinsic-sizing-ref.html
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LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-intrinsic-sizing.html
M Source/WebCore/rendering/GridTrackSizingAlgorithm.cpp
Log Message:
-----------
[grid-lanes] display:grid subgrid should contribute item sizes to correct
tracks
https://bugs.webkit.org/show_bug.cgi?id=307587
rdar://170168798
Reviewed by Sammy Gill.
When an explicitly placed subgrid uses display:grid (instead of
display:grid-lanes) inside a grid-lanes container, the subgrid's items
should contribute their intrinsic sizes only to the specific tracks
where they are placed, not to all tracks in the subgrid's span.
The issue was in computeDefiniteAndIndefiniteItemsForMasonry, which
determines whether items have indefinite positions based on their CSS
style (via resolveGridPositionsFromStyle). For auto-placed items inside
the subgrid, this returns indefinite even though a display:grid subgrid
has already placed them to specific tracks via its grid auto-placement
algorithm.
The fix checks whether the item's parent is a regular grid (not
grid-lanes) using isMasonry(). If so, we treat items as having definite
positions since the grid has placed them, and they contribute only to
their actual tracks rather than all tracks in the subgrid span.
Tests:
imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-display-grid-intrinsic-sizing-ref.html
imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-display-grid-intrinsic-sizing.html
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LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-display-grid-intrinsic-sizing-expected.html:
Copied from
LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-intrinsic-sizing-expected.html.
*
LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-display-grid-intrinsic-sizing-ref.html:
Copied from
LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-intrinsic-sizing-expected.html.
*
LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-display-grid-intrinsic-sizing.html:
Copied from
LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-intrinsic-sizing.html.
*
LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-intrinsic-sizing-expected.html:
*
LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-intrinsic-sizing-ref.html:
*
LayoutTests/imported/w3c/web-platform-tests/css/css-grid/grid-lanes/tentative/subgrid/track-sizing/grid-lanes-subgrid-intrinsic-sizing.html:
* Source/WebCore/rendering/GridTrackSizingAlgorithm.cpp:
(WebCore::GridTrackSizingAlgorithm::computeDefiniteAndIndefiniteItemsForMasonry):
Canonical link: https://commits.webkit.org/308253@main
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