bug#54488: 29.0.50; move-to-column/overlay-related regression in latest master, perhaps 28?

[Eli Zaretskii]

> From: João Távora <joaotavora@gmail.com>
> Cc: dgutov@yandex.ru,  54488@debbugs.gnu.org
> Date: Thu, 24 Mar 2022 16:03:59 +0000
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> An interesting one, though.  I think I follow.  Is there some easy way
> >> in Emacs to measure how many UTF-16 code units a given codepoint takes?
> >
> > That's easy: any codepoint above #xFFFF needs 2 UTF-16 code units.
> 
> >> I'm afraid I evicted this knowledge from the cache since I made that fix
> >> 2,5 years ago... Is a "codepoint" here a character in a string/buffer?
> >
> > Yes.
> 
> Indeed seems easy enough :-).  So
> 
> (defun measure (s) (cl-loop for c across s sum (if (> c #xFFFF) 2 1)))
> 
> ?

Yes, I think so.