Bug 288819 – [css-grid] `ASSERT(!isCalculated())` in `Length::value()` is hit under `RenderGrid::computeAutoRepeatTracksCount()` when loading https://kizu.dev/position-driven-styles/

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[Antoine Quint]

If you load https://kizu.dev/position-driven-styles/ with a ToT (291310@main) debug build, you hit `ASSERT(!isCalculated())` in `Length::value()` under a line `RenderGrid::computeAutoRepeatTracksCount()`. This occurs as the `transform` computed style is requested.

[Antoine Quint]

This page uses Scroll-driven Animations and that assertion is not hit if that flag is disabled. However the stack trace does not involve the animation code.

[Radar WebKit Bug Importer]

<rdar://problem/146466356>

[Sammy Gill]

Created attachment 475098 [details]
Reduced test case

Attaching reduced test case. It seems like this code is attempting to apply the following logic from the spec when it comes to determine the count of the auto repeat rows:

"For this purpose, each track is treated as its max track sizing function if that is definite or else its min track sizing function if that is definite. If both are definite, floor the max track sizing function by the min track sizing function. If neither are definite, the number of repetitions is one."

https://drafts.csswg.org/css-grid-2/#auto-repeat

We seem to fail to consider calc values here and presumably we should be using valueForLength in order to compute a proper value

[Sammy Gill]

Pull request: https://github.com/WebKit/WebKit/pull/44764

[Sammy Gill]

Submitted web-platform-tests pull request: https://github.com/web-platform-tests/wpt/pull/52275

[EWS]

Committed 294374@main (417c5cd1cddf): <https://commits.webkit.org/294374@main>

Reviewed commits have been landed. Closing PR #44764 and removing active labels.