Bug 239101

Summary: REGRESSION (r292043): [ Mac ] fast/block/positioning/fixed-container-with-relative-parent.html is a flaky image failure
Product: WebKit Reporter: Karl Rackler <rackler>
Component: New BugsAssignee: zalan <zalan>
Status: RESOLVED FIXED    
Severity: Normal CC: changseok, commit-queue, esprehn+autocc, ews-watchlist, glenn, koivisto, kondapallykalyan, pdr, simon.fraser, webkit-bot-watchers-bugzilla, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
See Also: https://bugs.webkit.org/show_bug.cgi?id=181834
Bug Depends on: 239305    
Bug Blocks:    
Attachments:
Description Flags
Actual
none
Expected
none
Patch
none
Patch
none
Patch
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Patch none

Description Karl Rackler 2022-04-11 19:48:14 PDT 
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
Comment 1 Karl Rackler 2022-04-11 19:48:44 PDT 
Created attachment 457308 [details]
Expected
Comment 2 Radar WebKit Bug Importer 2022-04-11 19:49:34 PDT 
<rdar://problem/91603539>
Comment 3 Karl Rackler 2022-04-12 10:47:18 PDT 
Marked expecrtation here while the issue is investigated.
r292777
Comment 4 zalan 2022-04-12 21:33:52 PDT 
Created attachment 457506 [details]
Patch
Comment 5 zalan 2022-04-13 07:35:51 PDT 
Created attachment 457530 [details]
Patch
Comment 6 zalan 2022-04-13 08:47:01 PDT 
Created attachment 457535 [details]
Patch
Comment 7 Simon Fraser (smfr) 2022-04-13 11:09:45 PDT 
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)?
Comment 8 zalan 2022-04-13 11:13:03 PDT 
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..."
Comment 9 EWS 2022-04-13 11:51:31 PDT 
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].
Comment 10 WebKit Commit Bot 2022-04-13 15:20:00 PDT 
Re-opened since this is blocked by bug 239305
Comment 11 zalan 2022-04-13 18:37:10 PDT 
Created attachment 457583 [details]
Patch
Comment 12 EWS 2022-04-13 20:58:08 PDT 
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].