[Bug target/51921] [4.6/4.7 regression] EH unwinding support is broken

["ro at CeBiTec dot Uni-Bielefeld.DE" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51921

--- Comment #3 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> 2012-02-07 16:59:32 UTC ---
> --- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-02-07 15:37:54 UTC ---
> Only sparc-sun-solaris2.10 is a primary target at the moment.  Rainer, you
> say "regression from 4.6" but the summary says 4.6/4.7 regression, not 4.7
> regression.  No known-to-work/known-to-fail field.  Does this only affect Ada?
>
> Please clarify.

I'd only noticed the breakage on mainline at first, but Eric reverted
the patch to support Solaris 11 on both mainline and the 4.6 branch, so
it indeed regressed on both branches.

It doesn't affect only Ada, but Java, too, which chooses to ignore.

I'm quite upset about this because the only reason for that reversion
he's given so far is a failure (I wouldn't call it regression) on a
7-year-old Solaris 10 beta release (or rather, one of many two-weekly
builds).  AFAICT, no released version is affected by my rewrite of
sparc/sol2-unwind.h, which introduced Solaris 11 support before 4.6.0,
which is now completely broken.

I don't buy his compatibility argument for several reasons:

* Even Sun/Oracle makes no compatibility guarantee of any sort for
  betas, and can break it if need we.  I don't see us making stronger
  guarantees in FSF GCC, especially to keep prehistoric betas working at
  the expense of the latest shipping release.

* Such versions are completely untestable: I've been in the Solaris 10
  Express and Platinum Beta programs myself, and ran practically every
  single one of those bi-weekly builds (that's what s10_72 is) on my
  machines, but didn't keep the ISO images for space reasons.

* If some AdaCore customer couldn't be bothered to upgrade to a release
  (I'm talking about any release here, not supported or latest) version
  of Solaris in 7 years, but needs to run bleeding-edge versions of GCC,
  I declare that AdaCore's problem, not mine.  If the only ill effect of
  a patch of mine is to break such ancient beta versions (not
  intentionally or lightly), so be it.  I'm not jumping through hoops to
  fix that.

I'm sort of tempted to revert Eric's reversion to restore working
Solaris 11 support in 4.6 and mainline, but would only do that as a very
last resort.

    Rainer