1901688 - [wpt-sync] Sync PR 46685 - [anchor] Update OOF style correctly when nothing fits

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, task, P4)

Description

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Sync web-platform-tests PR 46685 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/46685
Details from upstream follow.

Anders Hartvoll Ruud <[e-mail]> wrote:

[anchor] Update OOF style correctly when nothing fits

We currently have a bug when updating the OOF style for an element
that:

• Does not contain any anchor*() functions (or similar).
• Has an overflowing base style.
• Has at least one item in position-try-options, all of which overflow.

In the above case, neither the base attempt nor the position-try-option
attempts are successfully placed within the CB, and during OOF style
iteration (OOFCandidateStyleIterator) we then go back to the base
styles. The problem is that this we'll then call UpdateStyleForOutOfFlow
with try_set=nullptr and tactic_list=\<empty>, which (absent any anchor()
queries) causes the current logic to think that no update is needed.
However, the ComputedStyle currently held by the element is the style
from the last (failed) position-try attempt, so an update is needed
if we want to back to base.

To fix this:

• A call to UpdateStyleForOutOfFlow is now unconditional.
  It will always recalculate the style.
• When OOFCandidateStyleIterator is initialized, we check if
  we depend on anchor*() queries, and if so update the style.
  This initialization is reached by all OOFs, not just those that
  use anchor positioning features.
• All other calls to UpdateStyle in OOFCandidateStyleIterator
  will always lead to a style recalc. That's because these calls only
  take place when there's some position-try-option being processed,
  which are exactly the cases where we always need to recalc the style.

Fixed: 339686368
Change-Id: I046e20527e29924d8b6fbbd794232f51b7a2bb59

Reviewed-on: https://chromium-review.googlesource.com/5616572
WPT-Export-Revision: ec4ffbc5298535d41ef59dff46e75b9e746adf31

Comment 1

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Pushed to try (stability) https://treeherder.mozilla.org/#/jobs?repo=try&revision=46d193acad9f052781be196b3e451177a63b1819

Comment 2

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

CI Results

Ran 0 Firefox configurations based on mozilla-central, and Firefox, Chrome, and Safari on GitHub CI

Total 2 tests

Status Summary

Firefox

OK : 1
PASS : 2

Chrome

OK : 1
CRASH: 1
FAIL : 1

Safari

OK : 1
PASS : 2

Links

GitHub PR Head
GitHub PR Base

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b8acacc3af10
[wpt PR 46685] - [anchor] Update OOF style correctly when nothing fits, a=testonly

Comment 4

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/b8acacc3af10