bug#18610: 24.4.50; Specific file causing emacs to segfault upon opening

[Eli Zaretskii]

> From: Andreas Schwab <schwab@linux-m68k.org>
> Cc: Kenichi Handa <handa@gnu.org>,  dmantipov@yandex.ru,  
> maden.ldm@gmail.com,  18610@debbugs.gnu.org
> Date: Fri, 03 Oct 2014 17:16:27 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Btw, there's one more issue that bothers me.  In ONE_MORE_BYTE we have
> > this:
> >
> >     c = *src++;                                             \
> >     if (multibytep && (c & 0x80))                   \
> >       {                                                     \
> >     if ((c & 0xFE) == 0xC0)                         \
> >       c = ((c & 1) << 6) | *src++;                  \
> >     else                                            \
> >       {                                             \
> >         src--;                                      \
> >         c = - string_char (src, &src, NULL);        \
> >         record_conversion_result                    \
> >           (coding, CODING_RESULT_INVALID_SRC);      \
> >       }                                             \
> >       }                                                     \
> >
> > If 'src' is a signed type
> 
> It never is.

You are right.  But c nevertheless does get assigned a negative value
when the byte at src is beyond 127, at least according to what GDB
shows me.