[Bug target/67973] All the tests for -gstabs* fail on x86_64-apple-darwin14 with Xcode 7

[ro at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67973

--- Comment #4 from Rainer Orth <ro at gcc dot gnu.org> ---
(In reply to mrs@gcc.gnu.org from comment #2)
> Ah, found it, use the GNU assembler.  Maybe a little tricky, as one day,
> even that will be removed.  At that point, I think we just reject the
> -gstabs option.  The other option, is to just reject that now on darwin14+
> (or wherever it no longer works).

I believe every static approach is doomed to fail: why not just add a configure
test like this:

* first check if the configured assembler can assemble a trivial .stabs line

* if this fails, try again if it works with -Q added

* if this fails, too, disable both DBX_DEBUGGING_INFO and remove DBX_DEBUG from
  PREFERRED_DEBUGGING_TYPE

This should allow us to support Stabs while possible, but reject the
corresponding
options once the assembler cannot handle them.

  Rainer