bug#70014: 29.2; debugging with gdb problem with input/output buffer

[Eli Zaretskii <eliz@gnu.org>]

> From: Richard Stallman <rms@gnu.org>
> Cc: careless@live.it, 70014@debbugs.gnu.org
> Date: Thu, 28 Mar 2024 18:03:36 -0400
> 
>   > This feature doesn't work on MS-Windows because the underlying GDB
>   > feature (set inferior-tty) doesn't.  If someone knows how to fix that,
>   > patches are very welcome, but they are are probably need to be
>   > submitted to GDB, not to Emacs.
> 
> Emacs should at least five a clear error message.
> That it can do without changes in GDB.  For users to know
> that this usage is unsupported in GDB would be a big help.

gdb-inferior-io--init-proc silently punts when it cannot get a useful
name from process-tty-name.  It always did that.  This initialization
is done during initialization of the session, where displaying error
messages is tricky at best, and I also don't know what message to
display, TBH.  But patches are welcome.

> I would guess that there are fundamental reasons it is not supported

Yes: Emacs on Windows uses pipes to communicate with subprocesses,
because PTYs don't exist or cannot be used by Emacs.  So there's no
name of a TTY to use in the "set inferior-tty" command.