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

[Alan Mackenzie]

Hello, Eli.

On Sat, Aug 26, 2017 at 21:12:04 +0300, Eli Zaretskii wrote:
> > Date: Sat, 26 Aug 2017 17:06:59 +0000
> > Cc: 28242@debbugs.gnu.org
> > From: Alan Mackenzie <acm@muc.de>

> > Perhaps the problem is that that function (or some equivalent) isn't
> > being called, and Emacs is outputting non-displayable characters
> > regardless.

> 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, but
surely using_utf8 will return non-zero.  I _am_ using utf8.

> 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.

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.

-- 
Alan Mackenzie (Nuremberg, Germany).