bug#61667: 29.0.60; Failure to redisplay

[Dmitry Gutov]

On 21/02/2023 14:58, Eli Zaretskii wrote:
> > Cc:61667@debbugs.gnu.org
> > Date: Tue, 21 Feb 2023 12:43:29 +0200
> > From: Dmitry Gutov<dgutov@yandex.ru>
> >
> > With --eval '(trace-redisplay t)', redisplay always happens. ;-(
> That's strange: trace-redisplay just adds calls to functions that
> write to stderr, but doesn't change the display code in any way that
> could affect the control or data flow.  So, unless this is some weird
> compiler bug, I don't understand how trace-redisplay could have
> affected this.  Although the fact that with a tool bar displayed you
> cannot reproduce the problem is already weird for the same reason.
>
> If you build with no optimizations (CFLAGS=-O0 ./configure...), but
> without --enable-checking=glyphs, does the problem still happen?

Still reproduces, yes. As long as I don't hurry too much to type 'C-x b 
file-name RET' too early, before the frame has managed to resize and 
redisplay fully the first time.

So if I wait for it, and then use 'C-x b' (with Ido's support for 
recentf), then I also can trigger the problem.

Oh, here's another description of the bug: the frame's title bar changes 
(to display the visited file name), but the buffer is blank for a little 
while.

> > That's not the effect of 'checking', though -- I can still repro if I
> > don't turn on redisplay tracing (which prints stuff in the background
> > window; maybe it's relevant, maybe it's not).
> By "background window" you mean a shell window from which you started
> Emacs?  Or do you mean something else?

Yes, that one.