[Bug fortran/54572] Use libbacktrace library

["jb at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54572

--- Comment #9 from Janne Blomqvist <jb at gcc dot gnu.org> 2012-11-27 08:58:59 UTC ---
(In reply to comment #7)
> Why are there no line numbers in the backtrace from gdb?  You said you compiled
> with -g.  Are you sure that libbacktrace itself was compiled with -g?

I meant that I compiled the Fortran testcase with -g; GCC itself, including
libbacktrace, was built with default flags which ought to be "-O2 -g", but I
didn't specifically check how libbacktrace was built. Now that you mention it,
it does indeed seem like libbacktrace doesn't have debug symbols for some
reason.

(In reply to comment #8)
> The crash within libbacktrace is occurring as it tries to read the debug info. 
> This is presumably a bug in libbacktrace, but I don't know what the problem is
> without more information.  libbacktrace is pretty careful to only read memory
> that was explicitly read.  There is presumably a bug there, but I don't know
> what it is.
> 
> I doubt the fact that a signal occurred has anything to do with this.  There
> seems to be something odd about the debug info, as shown both by the fact that
> libbacktrace crashes trying to read it and that gdb does not display file/line
> information.

I forgot to mention, that I'm able to get a symbolic backtrace from outside a
signal handler. Though in that case my testcase used external procedures rather
than module procedures, so I guess it's possible there's a bug in handling
debug info for module procedures. I'll recheck this..