bug#28242: Batch mode compiling: Error messages are displayed with "invalid character" glyph bounding symbols.

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 26 Aug 2017 19:24:31 +0000
> Cc: 28242@debbugs.gnu.org
> From: Alan Mackenzie <acm@muc.de>
> 
> > No, I think the problem is in the function using_utf8, called from
> > 'main'.  Does it return true in your case?
> 
> I haven't worked out how to hook up gdb to a batch mode Emacs yet

 $ gdb ./emacs
 ...
 (gdb) break using_utf8
 (gdb) r -batch ... <rest of arguments here>

> > If so, what does terminal-coding-system return in your case in the
> > -batch invocation, and what is the value of locale-coding-system in
> > that case?
> 
> In an interactive session, terminal-coding-system is utf-8-unix and
> locale-coding-system is also utf-8-unix.
> 
> But I would be disturbed if my batch mode session didn't report
> utf-8-unix, or something similar.  It's running on an up to date
> GNU/Linux system.

If you locale's codeset is UTF-8, then how come your terminal cannot
display those quote characters?

> Surely Emacs doesn't assume from the use of UTF8 that curly quotes are
> displayable?  Those quotes are merely two characters from several
> hundred thousand, and not all of these are going to be displayable.  On
> a Linux tty, as I use, there is a maximum of 256 displayable glyphs.
> Most UTF8 characters aren't displayable.

We are not interested in all of the Unicode characters, we are only
interested in a few of them.

Anyway, I think it works for everyone else, the question is why
doesn't it work for you?