bug#61934: 28.2; Exec format error when `default-directory` contains non-ASCII characters on Windows 11

[Grzegorz Kowzan]

Thank you for the explanation. Can the code page be changed from within Emacs 
or is it set for good at startup? I tried changing the codepage to cp1250, 
which can handle all the characters in the directory name, with appropriate 
commands but I still get the same errors. When I execute 
(describe-coding-system) I get:

Coding system for saving this buffer:
  Not set locally, use the default.
Default coding system (for new files):
  * -- windows-1250 (alias: cp1250)

Coding system for keyboard input:
  * -- windows-1250-unix (alias: cp1250-unix)

Coding system for terminal output:
  * -- cp1250 (alias of windows-1250)

Coding system for inter-client cut and paste:
  U -- utf-16le-dos

Defaults for subprocess I/O:
  decoding: * -- windows-1250-dos (alias: cp1250-dos)

  encoding: * -- windows-1250-unix (alias: cp1250-unix)

Priority order for recognizing coding systems when reading files:
  1. windows-1250 (alias: cp1250)
  2. utf-8 (alias: mule-utf-8 cp65001)
...

which looks good to me. On the other hand, I did check that I can execute 
commands from a directory named C:/þñÜ, which has characters beyond ASCII that 
are handled by cp1252.

Best regards,
Grzegorz

On Fri, Mar 3, 2023, at 15:41, Eli Zaretskii wrote:
>> Date: Fri, 03 Mar 2023 14:56:32 +0100
>> From: "Grzegorz Kowzan" <grzegorz@kowzan.eu>
>> 
>> Calling external commands fails on Emacs under Windows 11 if
>> `default-directory' contains non-ASCII characters. Steps to reproduce:
>> 
>> 0. Start emacs -Q
>> 1. Create directory C:/zażółćgęśląjaźń.
>> 2. Enter the directory with dired.
>> 3. Press M-! and try executing any command.
>> 4. Minibuffer shows error message: "Spawning child process: Exec format 
>> error"
>
> This is expected.  Emacs on Windows supports starting programs only if
> the command-line arguments, including the program's file name, can be
> encoded in the system's codepage.  According to this bug report, your
> system codepage is 1252, and the file name you show cannot be encoded
> using that codepage.
>
> This is a limitation of how Emacs on Windows invokes programs, but the
> root cause is that many programs that run on Windows only support the
> current codepage, and cannot support UTF-8 due to Windows misfeatures.
>
> Sorry.