Re: [Libreoffice] gdb: catching exceptions...

I'm re-sending this note... I sent it yesterday via gmane, but I guess
this list is configured for moderation even in that situation; so today
I joined.

Mark Wielaard pointed out this note to me.
Feel free to CC 'archer@sourceware.org' on hacks like this, we're
interested in hearing about them and to find out what developers need
from gdb.

Michael> since my smoketest failed again today, i've distracted myself a bit
Michael> with GDB Python scripting, the result of which is a command that can
Michael> break when an exception is thrown, but only if a certain function
Michael> (which is given as parameter) is on the stack.

Nice.

Michael> seems to work, but it is quite slow: finding the smoketest exception
Michael> in SfxBaseModel::getTitle takes GDB 4 minutes of CPU time.

Michael> now probably somebody will tell me that i'm too stupid to RTFM and
Michael> there is a much simpler way to do this :)

There isn't a simpler way right now.  You could try to do it by having a
breakpoint on the function you care about that keeps a count of entries
and exits and enables the __cxa_throw breakpoint if this is nonzero.
However, this is hard to do reliably right now, because you have to do a
lot of manual management of return breakpoints.  I think this may get
simpler when the "finish breakpoint" feature goes in:

http://sourceware.org/ml/gdb-patches/2011-10/msg00394.html

We're interested in hearing about real-life uses of exceptions and what
better functionality gdb could provide.  Freely file feature requests in
gdb bugzilla; enhancing C++ development is a primary goal of ours these
days.

thanks,
Tom