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

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

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

--- Comment #5 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> 2012-02-07 17:29:37 UTC ---
> --- Comment #4 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2012-02-07 17:12:26 UTC ---
>> 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.
>
> If you give me a proof that no released version whatsoever, from the very first
> Solaris 8 to the very latest Solaris 10, can be affected by a regression due to
> the rewrite of the pattern matching code, then I'd (reluctantly) accept the
> breakage for the Solaris 10 beta.  

You know perfectly well that such a proof is practically impossible:
that would mean updating a machine through every single Solaris 8/9/10
kernel/libc/libthread patch ever released.  The other way round, I'd
claim that you cannot prove that the old code works for every since such
combination either.

>> * 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.
>
> Let's not misrepresent things, please.  Enhancing the existing pattern matching
> code is trivial: you find the first differing frame in the stack, and you add a
> new 'else if' somewhere.

You claimed that before, and that's what I tried at first to make
Solaris 11 work, but failed completely.

> Again, this pattern matching code is at least one decade old and went through
> many Solaris versions, so rewriting it from scratch was a wrong decision.

Why didn't you object then when it was submitted *and accepted*, has
been in for almost a year, been shipped with a release, and revert it
shortly before the next release?

    Rainer