bug#66317: Project mode-line

[Eli Zaretskii]

> Cc: sbaugh@catern.com, 66317@debbugs.gnu.org
> From: Juri Linkov <juri@linkov.net>
> Date: Mon, 16 Oct 2023 20:01:36 +0300
> 
> There is another problem: calling 'project-name' while evaluating
> 'mode-line-format' often changes the coding system mode-line indicator
> from U (utf-8) to raw-text during saving the current buffer.
> 
> Here is a backtrace:
> 
> - project-name
> - project--value-in-dir (that uses with-temp-buffer)
> - hack-dir-local-variables-non-file-buffer
> - hack-local-variables-apply
> 
> Then in the last function the coding system is broken
> in two different ways:
> 
> 1. by 'hack-one-local-variable' in `emacs -Q`

How and where?

> 2. by (run-hooks 'hack-local-variables-hook)
>    in buffers where flyspell-mode is enabled
>    'flyspell-hack-local-variables-hook' breaks
>    the coding system too.

Why?