bug#63589: [PATCH] 29.0.91; crash after creating graphical frames via emacsclient when compiled with cairo-xcb

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Cc: 63589@debbugs.gnu.org,  Thiago Melo <tmdmelo@gmail.com>
> Date: Mon, 22 May 2023 10:48:43 +0800
> 
> Po Lu <luangruo@yahoo.com> writes:
> 
> > The situation in which this crash occurs is sufficiently uncommon.  It's
> > the result of another bug in Emacs, hopefully one that should be safe to
> > fix.
> 
> Unfortunately, both this crash and its cause (actually, a
> RenderBadPicture from a glyph compositing request somewhere within
> cairo) are bugs in cairo-xcb itself.  Emacs never allows the display
> connection to be closed without dereferencing all Cairo resources
> created for that display connection, but Cairo keeps its own references
> around.

Was this bug reported to the relevant Cairo developers?

> The only reasonable solution is to disable the use of XCB surfaces by
> default.  Is this OK for the release branch?

It's OK, but please also add to NEWS some short notice about this
option and its potential pitfalls, which explain why it is off by
default.  Perhaps also about its advantages, so that users could make
up their minds.

What is the kind of situations in which these crashes could happen?