bug#51602: 29.0.50; Slow completion on Windows 10 when symbol name contains unicode

[Eli Zaretskii]

> From: No Wayman <iarchivedmywholelife@gmail.com>
> Date: Thu, 04 Nov 2021 15:51:53 -0400
> 
> 1. emacs -Q
> 2. define the following command:
> 
> (defun testಠ-ಠ () 
>   (interactive) nil)
> 
> 3. Attempt completion

I assume "attempt completion" means something like

  M-x t TAB

?  If so, I'm unable to reproduce this here.

Does that user have a font installed that is capable of displaying
those special characters (they are from the Kannada script)?  If not,
the time delay might be Emacs searching the system for a suitable
font.

> They claim completion will "hang" for some time. They also claim 
> including the command in an init file will cause the init time to 
> take 5 seconds longer.

I'd be interested in seeing the smallest possible init file that
causes such a long delay.

> We have a single alias in straight.el which includes ಠ-ಠ in the 
> symbol name. My reading of:
> 
> https://www.gnu.org/software/emacs/manual/html_node/elisp/Symbol-Type.html
> 
> seems to indicate that unicode characters in a symbol name should 
> be fine. Is that my misunderstanding?

Your understanding is correct.