bug#17753: Cygwin emacs-X11 core dump

[Eli Zaretskii]

> Date: Thu, 09 Oct 2014 10:17:47 +0200
> From: Markus Hoenicka <markus.hoenicka@mhoenicka.de>
> Cc: kbrown@cornell.edu, 17753@debbugs.gnu.org
> 
> This time with gdb's crash message. FWIW, I was hitting the backspace 
> key to erase some characters from an XML document in a nXML buffer.
> 
> Program received signal SIGSEGV, Segmentation fault.
> face_for_char (f=0x100f45c48 <bss_sbrk_buffer+6331368>, 
> face=face@entry=0x0,
>      c=101, pos=17134, object=object@entry=4304695346)
>      at /usr/src/debug/emacs-24.3.93-3/src/fontset.c:917
> 917         return face->ascii_face->id;

Why do you think it's the same problem?  It looks very different to
me, judging by the backtrace.

> #0  0x00000001005a1673 in face_for_char (f=0x100f45c48 
> <bss_sbrk_buffer+6331368>, face=face@entry=0x0, c=101, pos=17134, 
> object=object@entry=4304695346)
>      at /usr/src/debug/emacs-24.3.93-3/src/fontset.c:917
> #1  0x0000000100428c1a in get_next_display_element 
> (it=it@entry=0x425c30)
>      at /usr/src/debug/emacs-24.3.93-3/src/xdisp.c:7139

What do the following GDB commands produce?

 (gdb) thread 1
 (gdb) frame 1
 (gdb) print it->what
 (gdb) print it->face_id
 (gdb) print FRAME_FACE_CACHE (it->f)->used
 (gdb) print face