Any update? Still an issue today...

+1

I agree, fixing this would be really appreciated.

Same here, this bug only happens on Safari :-\

Created attachment 427252 [details]
Patch

I've uploaded also a patch for WPT with the tests from Blink in here https://chromium-review.googlesource.com/c/chromium/src/+/2856537

If they got approved I'd just import them instead of adding these ones to imported/blink

Created attachment 427262 [details]
Patch

Created attachment 427335 [details]
Patch

Comment on attachment 427335 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=427335&action=review

> Source/WebCore/rendering/RenderElement.cpp:179
> +        // list-item should have no effect for <summary> as they're already list items. Let it
> +        // fallthrough to the default case where it will create a RenderBlockFlow.
> +        if (creationType == CreateAllRenderers)
> +            return createRenderer<RenderListItem>(element, WTFMove(style));
> +        FALLTHROUGH;

I don't understand this. If you fall through here you are going to create RenderFlexibleBox not RenderBlockFlow.

Also what does "as they're already list items" mean?

Comment on attachment 427335 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=427335&action=review

>> Source/WebCore/rendering/RenderElement.cpp:179
>> +        FALLTHROUGH;
> 
> I don't understand this. If you fall through here you are going to create RenderFlexibleBox not RenderBlockFlow.
> 
> Also what does "as they're already list items" mean?

Right that's intended. If we specify "display:list-item" then we want the <summary> to have a RenderFlexibleBox as renderer because we don't want them to be rendered as list items as they already have a marker before the text (we would end up with 2 markers, one for the list item and another for the summary, no other engine does that). The "as they're already list items" is indeed a pretty bad wording for what I mentioned before.

Created attachment 427345 [details]
Rendering sample

I hope this screenshot could help me explain my point about summary as a list item. Left, current status, we get a double marker one for the list item and another one for the summary. Right the new rendering with the patch, only the marker for the summary is shown.

Comment on attachment 427335 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=427335&action=review

>>> Source/WebCore/rendering/RenderElement.cpp:179
>>> +        FALLTHROUGH;
>> 
>> I don't understand this. If you fall through here you are going to create RenderFlexibleBox not RenderBlockFlow.
>> 
>> Also what does "as they're already list items" mean?
> 
> Right that's intended. If we specify "display:list-item" then we want the <summary> to have a RenderFlexibleBox as renderer because we don't want them to be rendered as list items as they already have a marker before the text (we would end up with 2 markers, one for the list item and another for the summary, no other engine does that). The "as they're already list items" is indeed a pretty bad wording for what I mentioned before.

The part I don't understand is that your code comment says "Let it fallthrough to the default case where it will create a RenderBlockFlow" while it actually creates a RenderFlexibleBox.

Comment on attachment 427335 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=427335&action=review

>>>> Source/WebCore/rendering/RenderElement.cpp:179
>>>> +        FALLTHROUGH;
>>> 
>>> I don't understand this. If you fall through here you are going to create RenderFlexibleBox not RenderBlockFlow.
>>> 
>>> Also what does "as they're already list items" mean?
>> 
>> Right that's intended. If we specify "display:list-item" then we want the <summary> to have a RenderFlexibleBox as renderer because we don't want them to be rendered as list items as they already have a marker before the text (we would end up with 2 markers, one for the list item and another for the summary, no other engine does that). The "as they're already list items" is indeed a pretty bad wording for what I mentioned before.
> 
> The part I don't understand is that your code comment says "Let it fallthrough to the default case where it will create a RenderBlockFlow" while it actually creates a RenderFlexibleBox.

Oh yeah, that's wrong. The whole comment is really misleading, sorry about that. Yeah the idea is that in the case of a <summary> element with display:list-item we'll create a flexbox instead of a RenderListItem. I'll revamp it

Created attachment 430192 [details]
Patch

Committed r278280 (238317@main): <https://commits.webkit.org/238317@main>

<rdar://problem/78689690>