1840782 - WPT css/css-flexbox/flex-aspect-ratio-img-column-008.html fails in Firefox, due to float clearance difference

Status: NEW

(Core :: Layout: Floats, defect)

Description

[Daniel Holbert [:dholbert]]

We fail this WPT:
https://wpt.fyi/results/css/css-flexbox/flex-aspect-ratio-img-column-008.html
http://wpt.live/css/css-flexbox/flex-aspect-ratio-img-column-008.html

The WPT is trying to test percent resolution, but the reason we fail is something entirely different.

The testcase has a floated green div, with a green flex container following it, and it's expecting them to end up side-by-side. However, Firefox seems to treat the writing-mode-change as a reason to clear the float, i.e. push the flex container down below the float.

Other browsers match our rendering if I add clear:both to the flex container; this confirms that this float-clearance is what's going on here.

(I need to do some digging to determine whether there's any reason that this float-clearance behavior might be correct. In the meantime, it might be worth adjusting the test to avoid tripping this bug, since the test is otherwise 100% interoperable and it's odd for it to be ostensibly a flexbox interop test but really just testing an obscure orthogonal-writing-mode float clearance bug.)

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: testcase 1

Here's a reduced testcase. In Firefox, the cyan div ends up below the float. In other browsers, it ends up to the right of the float.

If I add an explicit width to the cyan div (e.g. width:50px), then we change to match other browsers, i.e. we stop clearing the float.

So I suspect this is related to bug 1310551 and general issues around intrinsic sizing and orthogonal writing modes.

Comment 3

[[:anutrix]]

Blocks interop-2026-flexbox too: https://wpt.fyi/results/css/css-flexbox?label=master&label=experimental&aligned&view=interop&q=label%3Ainterop-2021-flexbox%20or%20label%3Ainterop-2023-flexbox%20or%20label%3Ainterop-2021-grid%20or%20label%3Ainterop-2023-grid%20or%20label%3Ainterop-2022-subgrid