[Bug target/47558] 163267 breaks exception traceback in xplor-nih

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47558

--- Comment #26 from Iain Sandoe <iains at gcc dot gnu.org> 2011-02-01 18:40:53 UTC ---
(In reply to comment #25)
> Again, I would note Nick's original comments on these issues...


> So for compatibility with any Apple gcc built software, we should never
> allow the FSF gcc unwinder to become operational under any circumstances.

and that is how we have the design (the comment  applies to all versions of
Darwin, not just 10).

the only case where using the FSF unwinder would make any sense  is for
stand-alone code which does not link any system libs - not a likely scenario
for anything other than test-code.

You can defeat the design in various ways (e.g. setting DYLD_LIBRARY_PATHs) but
there's nothing we can do about that - everything is working as intended - if
the User instructs the compiler/linker to do incompatible things there is
little we can do.

The residual issue is that we are (99.9% likely) issuing unwind information
which is incompatible with the Darwin system unwinders - there have been fixes
posted for this, and it needs re-visiting - but, again, nothing to do with the
PR at hand.