On Fri, 21 Dec 2018 at 22:35, Jonathan Wakely <jwak...@redhat.com> wrote: > > I also explcitely define BACKTRACE_SUPPORTED to 0 to make sure > >libstdc++ has no libbacktrace dependency after usual build.
> I'm concerned about the requirement to link to libbacktrace > explicitly (which will break existing makefiles and build systems that > currently use debug mode in testing). But see what Francois wrote, "I also explcitely define BACKTRACE_SUPPORTED to 0 to make sure libstdc++ has no libbacktrace dependency after usual build." > Also, some of the glibc team pointed out to me that running *any* > extra code after undefined behaviour has been detected is a potential > risk. The less that you do between detecting UB and calling abort(), > the better. Giving the users more information is helpful, but comes > with some additional risk. Ditto. Having said those things, I think we need to figure out a good way to provide this sensibly as an opt-in. The backtrace support is bloody useful, and dovetails into a possible Contracts-aware implementation of our library, but I think we need to do some more thought-work on this, thus I agree that it's not stage3 material. I do think it's something that we need to keep in mind, thanks for working on it, Francois!
