bug#74922: 29.4; copy_string_contents doesn't always produce a valid utf-8

[Eli Zaretskii]

> From: Evgeny Kurnevsky <kurnevsky@gmail.com>
> Date: Tue, 17 Dec 2024 06:08:30 +0000
> 
> According to the docs and comment inside module_copy_string_contents it 
> should always produce a valid
> utf-8 string that can be used in dynamic modules, but it seems it's not 
> always the case. I encountered an
> emacs crash when using emacs-module-rs because it always expects a valid 
> utf-8 for strings. To reproduce
> you can call:
> 
> (some-function-from-dynamic-library (encode-coding-string (f-read-text 
> "wg-private-pc.age") 'utf-8 t))
> 
> The file is
> https://github.com/kurnevsky/nixfiles/raw/0b3de016dac551398627a55788b80d4809afcbf9/secrets/wg-private-pc.age

This string includes raw bytes, it isn't a text string, as far as I
could see.  It definitely isn't UTF-8 encoded text.  What did you
expect to happen with it when you copy such a string from Emacs?

> See https://github.com/ubolonton/emacs-module-rs/issues/58 for additional 
> details.

Can't say there are too many details there...