bug#75207: 29.4; Path conversion from native codepage to UTF-8 fails when Windows is set by default to UTF-8

[Eli Zaretskii <eliz@gnu.org>]

severity 75207 wishlist
thanks

> Date: Mon, 30 Dec 2024 12:12:02 +0000
> From: michal--- via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Emacs generates gibberish UTF-8 characters during conversion from native
> codepage to UTF-8 if experimental default UTF-8 codepage is set on
> Windows.

Please provide the minimum recipe for reproducing this, starting from
"emacs -Q".  What exactly did you convert, and how?  And what problems
did you see, exactly?  Also, what do the following commands produce
inside "emacs -Q"?

  M-: (getenv "ENU") RET
  M-: current-locale-environment RET
  M-: w32-ansi-code-page RET
  M-: (default-value 'buffer-file-coding-system) RET

In general, the UTF-8 codepage on Windows is not (yet) supported.  In
particular, some functions we use in Emacs assume the system codepage
cannot be a multibyte encoding.  Also, invoking subprocesses on
Windows doesn't currently support anything but single-byte encoding of
the program's name and its command-line arguments, for boring
technical reasons.  For that reason, I don't recommend using the UTF-8
codepage, and I don't recommend making UTF-8 the default encoding on
MS-Windows.

That said, presenting a clear recipe could help us gradually improve
support for this, as Windows improves its part in parallel.

Thanks.