bug#50983: 28.0.50; [REGRESSION, BUG] Display bugs with uncommon characters

[Rudi C]

> I see no Emacs problem here

But the problem does not happen with vim (nor with emacs 27 for `weird.txt`), so it is clearly an interaction of different elements. 

Anyhow, I have opened an [upstream issue](https://github.com/kovidgoyal/kitty/issues/4094). Please subscribe to it so that you might offer your emacs expertise there, if needed.

> changing the "character encoding" setting in iTerm to ASCII

This is a most loath workaround. I do want UTF-8, as I use mathematical symbols, emojis, and non-English languages. Anyhow, making the text full of random unrecognized characters is not much better than the current behavior.

On Sun, Oct 3, 2021 at 2:42 PM Eli Zaretskii <eliz@gnu.org> wrote:

> From: Rudi C <rudiwillalwaysloveyou@gmail.com>
> Date: Sun, 3 Oct 2021 14:30:56 +0330
>
> Also, can you be more specific about where you do observe the bugs? In TUI emacs on iTerm?
>
> I can confirm that the bug with `weird.txt` happens on iTerm, too, again with both emacs and neovim! But the
> bug with `bug.txt` does not happen in iTerm, only on Kitty.

This sounds like the terminal emulators have a problem in supporting
unusual Unicode characters, such as zero-width or double-width
characters, perhaps?  I see no Emacs problem here, since it happens
only on some terminal emulators and not on others.