GNU bug report logs - #15045
Point jumps inappropriately around time of Semantic lexing

Previous Next

Full log

View this message in rfc822 format

From: Eli Zaretskii <eliz <at> gnu.org>
To: Barry OReilly <gundaetiapo <at> gmail.com>
Cc: 15045 <at> debbugs.gnu.org, deng <at> randomsample.de
Subject: bug#15045: Point jumps inappropriately around time of Semantic lexing
Date: Wed, 07 Aug 2013 22:44:15 +0300

> Date: Wed, 7 Aug 2013 15:31:38 -0400
> From: Barry OReilly <gundaetiapo <at> gmail.com>
> Cc: 15045 <at> debbugs.gnu.org
> 
> > So it's "displayed at A" then "displayed at B" then "displayed at A
> > again"? what happens between each one of those 3 displays?
> 
> No. A, B, and C are backtraces. Specifically, the backtraces printed
> when goto-char went to the offending position at the beginning of the
> comment block. I don't know which of the three is the one I see
> actually displayed. The timestamps are too close together for me to be
> certain.
> 
> I'm interested to see if I get more empty backtraces at the next
> reproduction. I don't know what they could mean.
> 
> > If "nothing", then I suspect there's something like a `sit-for'
> > somewhere that causes a redisplay in the middle of the command (i.e.
> > in the middle of a save-excursion).
> 
> Ahh, I didn't know about sit-for. It might explain what I'm seeing.
> 
> I added a debug statement to Fredisplay. In a simple run (no
> reproduction of the bug yet), I get a few of these:
> 
> 2013-08-07T15:18:09.576922000|pid:11494|tid:47776720943360|dispnew.c|5822|
> DEBUG: redisplay
>   redisplay()
>   sit-for(0)
>   jit-lock-deferred-fontify()
>   apply(jit-lock-deferred-fontify nil)
>   byte-code("rÁÂHÃH\"ˆ)Á‡" [timer apply 5 6] 4)
>   timer-event-handler([t 0 0 10000 t jit-lock-deferred-fontify nil idle 0])
> 
> I don't suppose there are ways deferred jit lock would execute during
> Semantic lexing?

I think the jit-lock you see is the result of the scrolling, not its
reason.

> Anyway, next time I see the bug, I expect I'll get better data.

In the discussion that you cite at the beginning of this bug report, I
suggested a different approach to finding out the culprit, by using
the redisplay tracing facility.  Can you try that and post the
results?  It might give better clues.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.