369227 - "ASSERTION: Backuping up twice; this should never be necessary" with floats and vertical scrollbar

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[Jesse Ruderman]

Attachment: testcase

Loading the testcase triggers:

###!!! ASSERTION: Backuping up twice; this should never be necessary: '!forceBreakInContent', file /Users/jruderman/trunk/mozilla/layout/generic/nsBlockFrame.cpp, line 3074

This assertion was added in bug 343445.

http://quotes.burntelectrons.org/1892

Comment 1

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Attachment: fix

There are two parts to this fix:

1) The text frame "  A  " wants to try to place the following <span> after itself, just in case the span collapses completely into the text frame's trailing whitespace, even though the text frame's trailing soft break is beyond the available width. We need to fail to place the span and back up to the text frame's soft break. Problem is that up till now we haven't allowed potential breaks to be registered beyond the available width. This patch alters that, allowing us to record a break opportunity beyond the available width if there isn't already a (better) one recorded.

2) nsLineLayout::ClearOptionalBreakPosition needs to clear out the NEEDBACKUP flag so that nsBlockFrame::DoReflowInlineFrames doesn't assert, thinking that backup is required more often that it is.

Comment 2

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

Comment on attachment 254382 [details] [diff] [review]
fix

r+sr=dbaron.

Please also change the assertion text from "Backuping up" to "Backing up".

Comment 3

[Robert O'Callahan (:roc) (email my personal email if necessary)]

checked in.

Comment 4

[Jesse Ruderman]

Crashtest checked in.