1936156 - Poor interaction between scroll{Width,Height} and margin collapsing

Status: VERIFIED FIXED

(Core :: Layout: Scrolling and Overflow, defect)

Description

[Emilio Cobos Álvarez [:emilio]]

Attachment: Test-case.

When calling scroll{Width,Height} on an overflow: visible frame, after bug 1931490 we account for margins that have really collapsed through to our ancestor BFC. That causes us to report different client / scroll margins, which eventually end up confusing the matrix-react benchmark code (see bug 1931490 comment 14 and following).

Comment 1

[Emilio Cobos Álvarez [:emilio]]

Ok, diagnostic and test-case in bug 1936156.

Comment 2

[Emilio Cobos Álvarez [:emilio]]

err, obviously commented in the wrong bug :)

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1931490

Comment 4

[Emilio Cobos Álvarez [:emilio]]

Attachment: Bug 1936156 - Don't consider collapsed margins for in-flow line bounds if we're not a BFC. r=dshin,#layout

So that our client{Width,Height} and scroll{Width,Height} calculations
make sense.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a661bff10b1f
Don't consider collapsed margins for in-flow line bounds if we're not a BFC. r=dshin

Comment 7

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

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/49641 for changes under testing/web-platform/tests

Comment 8

[agoloman]

https://hg.mozilla.org/mozilla-central/rev/a661bff10b1f

Comment 9

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

Upstream PR merged by moz-wptsync-bot

Comment 10

[Emilio Cobos Álvarez [:emilio]]

Comment on attachment 9442577 [details]
Bug 1936156 - Don't consider collapsed margins for in-flow line bounds if we're not a BFC. r=dshin,#layout

Beta/Release Uplift Approval Request

• User impact if declined/Reason for urgency: Needed to uplift the regressor.
• Is this code covered by automated tests?: Yes
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: Yes
• If yes, steps to reproduce: Comment 0
• List of other uplifts needed: none
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Returns to pre regression behavior for a subset of cases.
• String changes made/needed: none
• Is Android affected?: Yes

Comment 11

[Ciprian Georgiu, Desktop QA]

I've reproduced the issue with an affected Nightly build (2024-12-09), using the test case from comment 0.

The issue is verified as fixed on latest Nightly 135.0a1 under Win 11 x64, macOS 14 and Ubuntu 22.04. The "[not-scrollable] scroll" and "[scrollable] scroll" client values are correctly matching.

Comment 12

[Pascal Chevrel:pascalc]

Comment on attachment 9442577 [details]
Bug 1936156 - Don't consider collapsed margins for in-flow line bounds if we're not a BFC. r=dshin,#layout

Approved for 134RC, thanks.

Comment 13

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-beta/rev/481144e61f76

Comment 14

[Ciprian Georgiu, Desktop QA]

This is also verified as fixed on 134 RC (treeherder build), running Win 11, macOS 14 and Ubuntu 24.04