bug#66764: 29.1; Emacs scrolls for "(goto-char (point-max))" instead of jumping

[Eli Zaretskii <eliz@gnu.org>]

Ping! Ping!  Gregory, are you there?

> Cc: 66764@debbugs.gnu.org, geza.herman@gmail.com
> Date: Sat, 04 Nov 2023 10:29:49 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> 
> Ping!  Gregory, could you please look into this?
> 
> > Cc: Gregory Heytings <gregory@heytings.org>, 66764@debbugs.gnu.org
> > Date: Fri, 27 Oct 2023 09:50:33 +0300
> > From: Eli Zaretskii <eliz@gnu.org>
> > 
> > OK, I think I see the root cause of the problem: it's your
> > font-lock-keywords setting, viz.:
> > 
> >  (font-lock-add-keywords nil '(((lambda (bound)) (1 'error prepend t))) t)
> > 
> > Without this setting, everything works as expected, and goto-char goes
> > to the EOB almost instantaneously, even when scroll-conservatively is
> > set to a large value.
> > 
> > AFAIU, the font-lock-keywords setting above causes the display engine
> > to call this function every time it moves across some chunk of text,
> > which slows down redisplay.  This shows with scroll-conservatively set
> > to a large value because Emacs then attempts to find the minimum
> > amount of scrolling the screen in order to bring point into the view.
> > 
> > It is a known fact that modes which use advanced font-lock settings
> > should adapt to the long-line situation (when the function
> > long-line-optimizations-p returns non-nil), so I think you should
> > modify your font-lock settings to avoid this problem in that case.
> > 
> > CC'ing Gregory in case I missed something in this scenario.
> > 
> > 
> > 
> > 
> 
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> 
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