bug#24205: 25.1.50; Re-display issue (lag) when opening certain files [sml-mode]

[Eli Zaretskii <eliz@gnu.org>]

> From: Kaushal Modi <kaushal.modi@gmail.com>
> Date: Thu, 11 Aug 2016 19:53:05 +0000
> Cc: bug-gnu-emacs@gnu.org, monnier@iro.umontreal.ca
> 
> The file has to contain just this sml comment:
> 
> =====
> (* ''a is a special equality type (it is not the same as the generic 'a type. It *) 
> ===== 
> 
> I cannot figure out what's special about this comment that freaks the re-display.

Most probably the unbalanced parentheses.  Something in sml-mode
causes the display engine to hit on that many times.

I will look into this.

>  Are you saying that just visiting this file exhibits the problem? 
> 
> Yes, in sml-mode.
> 
>  If
>  so, what modes should be turned on in the visiting buffer to see the
>  problem?
> 
> All my MWE is doing is:
> - Install sml-mode from GNU Elpa
> - Create a specific example file that causes this issue
> - Start profiler
> - Visit the file

I must explain something so that my requests don't sound arbitrary.
When I work on a problem, I usually run Emacs many times in different
ways, most of the times under a debugger.  Since the debugger (and
other tools) need to read my init files for working properly as I'm
used to, I cannot easily change my home directory, or mess with my
init files during the debugging session.  In addition, with 10-20 sec
delay I don't need a profiler to notice it.

So it is much more helpful to have a recipe that is as simple as
possible (so invoking it many times won't be painful), avoids
interfering with my init files and system configuration, and includes
only the stuff that is directly relevant to the bug reproduction.

A good recipe along the above lines could easily speed up a bugfix by
hours and even days.  So if you can afford that, please try to follow
these guidelines when you prepare a recipe.

I hope this clarifies the reason for my requests.

Thanks.