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

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

[No Wayman]

This is a bug that was reported to straight.el's repository. 
According to the user's report, it is reproducible from emacs -Q 
without straight.el. I asked them to report it here, but they 
refused (citing a "previous unpleasant experience with 
bugs-gnu-emacs").

To reproduce:

1. emacs -Q
2. define the following command:

(defun testಠ-ಠ () 
  (interactive) nil)

3. Attempt completion

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.
User claims Emacs 26, 27.2 and current master branch are all 
affected when built on Windows 10 (Home and Enterprise using 
MSYS2).

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?

Initial report:

https://github.com/raxod502/straight.el/issues/877

I'm unable to verify the reproduction case myself, as I don't have 
access to a Windows machine.
Apologies in advance if this is noise.

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.

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

[No Wayman]

Eli Zaretskii <eliz@gnu.org> writes:

> Your understanding is correct.

Thank you for confirming that.

I agree with your assessment that this is likely the result of the 
user's system configuration.
Appreciate you taking the time to address it at our repo.

Thanks again,

Nick

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

[Eli Zaretskii]

> From: No Wayman <iarchivedmywholelife@gmail.com>
> Cc: 51602@debbugs.gnu.org
> Date: Fri, 05 Nov 2021 12:23:21 -0400
> 
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Your understanding is correct.
> 
> Thank you for confirming that.
> 
> I agree with your assessment that this is likely the result of the 
> user's system configuration.
> Appreciate you taking the time to address it at our repo.

I think this bug can be closed now, since it turns out the "hang" is
due to Emacs looking for a suitable font for some special characters
(and not finding it, for some reason).

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

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> I think this bug can be closed now, since it turns out the "hang" is
> due to Emacs looking for a suitable font for some special characters
> (and not finding it, for some reason).

OK; closing.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no