371452 - nsIFrame::IsContainingBlock should not check style data

Status: RESOLVED WONTFIX

(Core :: Layout, defect)

Description

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

In bug 9458 comment 87, bzbarsky wrote:
> That said, nsBlockFrame overrides this function, so what are the cases when
> we'll hit this code with a non-nsBlockFrame that has
> NS_STYLE_DISPLAY_INLINE_BLOCK?

In bug 9458 comment 91, dbaron wrote:
> Probably pretty low.  I suppose it should perhaps even just return PR_FALSE so
> that we don't say that something that can't be a containing block is one.

In bug 9458 comment 92, dbaron wrote:
> In the patch to bug 367247 I decided to make it do the latter -- just return
> PR_FALSE, and add an IsContainingBlock to nsTableCellFrame.

In bug 9458 comment 93, dbaron wrote:
> I had to back the nsFrame part of that out due to orange; probably need to add
> overrides on nsViewportFrame / nsHTMLFrame or something similar.

I think we should perhaps consider making IsContainingBlock implementations not check style data, since there could be potential problems if a frame returns true but isn't capable of being one (although I don't think that's the case today).  But doing this requires adding a few more overrides of IsContainingBlock (particularly for the frames near the root of the frame tree).

Comment 1

[(no longer active)]

So, David: IsContainingBlock has now been removed.  With this replacement: https://hg.mozilla.org/mozilla-central/rev/00f422b2cf36#l11.40, is this still a concern?

Comment 2

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Per comment 1, I assume this bug is not a concern.