Re: master 6ed1994d27: Prevent crashes from illegal locale coding systems

[Eli Zaretskii <eliz@gnu.org>]

> From: Po Lu <luangruo@yahoo.com>
> Cc: emacs-devel@gnu.org
> Date: Wed, 16 Feb 2022 21:40:57 +0800
> 
> --- a/src/xterm.c
> +++ b/src/xterm.c
> @@ -8734,6 +8734,15 @@ handle_one_xevent (struct x_display_info *dpyinfo,
>  	      {
>  		/* Decode the input data.  */
>  
> +#ifdef HAVE_GLIB
> +		/* If this isn't done in a build with GLib (usually
> +		   with GTK), then the resulting signal in
> +		   `setup_coding_system' will cause Emacs to
> +		   crash.  */
> +		if (NILP (Fcoding_system_p (coding_system)))
> +		  goto done_keysym;
> +#endif
> +
>  		/* The input should be decoded with `coding_system'
>  		   which depends on which X*LookupString function
>  		   we used just above and the locale.  */

This isn't right, IMO.  You should decode using Qraw_text in the
problematic case.  Dropping the bytes on the floor is too radical,
certainly for the release branch.