Help getting backtrace in gdb

[Kaushal Modi <kaushal.modi@gmail.com>]

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Hello,

It has been a while (about a year) since I did backtracing in gdb. I
followed my notes from then to look at a backtrace for an emacs crash, but
it's not working.

km²~/downloads/:git/emacs/src> gdb ./emacs
GNU gdb (GDB) Red Hat Enterprise Linux (7.2-75.el6)
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html
>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /home/kmodi/downloads/git/emacs/src/emacs...done.
SIGINT is used by the debugger.
Are you sure you want to change it? (y or n) [answered Y; input not from
terminal]
DISPLAY = :1.0
TERM = tmux-24bits
Breakpoint 1 at 0x55c782: file emacs.c, line 364.
Temporary breakpoint 2 at 0x580423: file sysdep.c, line 1022.
(gdb) break Fsignal
Breakpoint 3 at 0x605535: file eval.c, line 1508.
(gdb) r -Q
Starting program: /home/kmodi/downloads/git/emacs/src/emacs -Q

(emacs:19646): GLib-GIO-CRITICAL **: g_settings_schema_source_lookup:
assertion 'source != NULL' failed

Backtrace:
[0x0]
[0x0]
[0x0]
During startup program terminated with signal SIGSEGV, Segmentation fault.
(gdb) bt
No stack.
You can't do that without a process to debug.

(If interested, this is what causes the crash on emacs -Q:
http://lists.gnu.org/archive/html/emacs-orgmode/2017-06/msg00508.html )

The difference in behavior I see is that the breakpoint on Fsignal is not
working.

I have built emacs from the latest version of master branch with these
options:

./configure options:
  --with-modules --prefix=/home/kmodi/usr_local/apps/6/emacs/master
'--program-transform-name=s/^ctags$/ctags_emacs/' 'CPPFLAGS=-fgnu89-inline
-I/home/kmodi/usr_local/6/include -I/usr/include/freetype2 -I/usr/include'
'CFLAGS=-ggdb3 -O0' 'CXXFLAGS=-ggdb3 -O0'
'LDFLAGS=-L/home/kmodi/usr_local/6/lib -L/home/kmodi/usr_local/6/lib64
-ggdb3'

Features:
  XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GCONF GSETTINGS
NOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK2 X11 MODULES

Has something changed about configure (some new flag that I need to add?)
to enable debug in gdb?
-- 

Kaushal Modi

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