Bug 239101 – REGRESSION (r292043): [ Mac ] fast/block/positioning/fixed-container-with-relative-parent.html is a flaky image failure

• Component: New Bugs
• Status: RESOLVED FIXED

[Karl Rackler]

Created attachment 457307 [details]
Actual

Description:
fast/block/positioning/fixed-container-with-relative-parent.html

The first image failure that I see this on the dashboard was 03/29/22 at r292045, but I was not able to find a commit that seemed relevant that would have caused this.

REPRODUCTION STEPS
I can reproduce this on r292043, but unable to reproduce on r292042.

Command: 
run-webkit-tests --root --exit-after-n-failures 1 --exit-after-n-crashes-or-timeouts 1 --iterations 50 fast/block/positioning/fixed-container-with-relative-parent.html

Result: 
[10/50] fast/block/positioning/fixed-container-with-relative-parent.html failed unexpectedly (reference mismatch maxDifference=255; totalPixels=1240)
Exiting early after 2 failures. 10 tests run.
8 tests ran as expected, 2 didn't (40 didn't run):

History:
https://results.webkit.org/?suite=layout-tests&test=fast%2Fblock%2Fpositioning%2Ffixed-container-with-relative-parent.html&platform=mac&limit=49920&version_name=Big%20Sur&version_name=Monterey

Link to image diff:
https://build.webkit.org/results/Apple-BigSur-Debug-AppleSilicon-WK2-Tests/r292729%20(5534)/fast/block/positioning/fixed-container-with-relative-parent-diffs.html

[Karl Rackler]

Created attachment 457308 [details]
Expected

[Radar WebKit Bug Importer]

<rdar://problem/91603539>

[Karl Rackler]

Marked expecrtation here while the issue is investigated.
r292777

[alan]

Created attachment 457506 [details]
Patch

[alan]

Created attachment 457530 [details]
Patch

[alan]

Created attachment 457535 [details]
Patch

[Simon Fraser (smfr)]

Comment on attachment 457535 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=457535&action=review

> Source/WebCore/rendering/RenderBlock.cpp:180
> +                for (auto it = descendants->begin(); it != descendants->end(); ++it) {

Does ListHashSet not support for (auto thing : *descendants)?

[alan]

Comment on attachment 457535 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=457535&action=review

>> Source/WebCore/rendering/RenderBlock.cpp:180
>> +                for (auto it = descendants->begin(); it != descendants->end(); ++it) {
> 
> Does ListHashSet not support for (auto thing : *descendants)?

It does have support for range loop, but in this case "it" is used at "descendants->insertBefore(it..."

[EWS]

Committed r292817 (249597@main): <https://commits.webkit.org/249597@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 457535 [details].

[WebKit Commit Bot]

Re-opened since this is blocked by bug 239305

[alan]

Created attachment 457583 [details]
Patch

[EWS]

Committed r292855 (249626@main): <https://commits.webkit.org/249626@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 457583 [details].