[Bug target/67896] Inconsistent behaviour between C and C++ for types poly8x8_t and poly16x8_t

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67896

James Greenhalgh <jgreenhalgh at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2016-01-11
                 CC|                            |jgreenhalgh at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #2 from James Greenhalgh <jgreenhalgh at gcc dot gnu.org> ---
Confirmed, and thanks for the detailed analysis and the candidate patch. I
think I agree with what your saying, and the patch looks like the right thing
to do to me (though I would refactor it to avoid the need for the bool, can we
not just pull the SET_TYPE_STRUCTURAL_EQUALITY check in to the if statement in
which you set is_vector?).

I was a little concerned that now a poly8_t and an int8_t would compare equal,
but I see that build_distinct_type_copy sets TYPE_CANONICAL correctly for the
scalar poly types, so I don't have to worry.

Please submit your patch to the mailing list along with the testcase here
annotated with the relevant dejagnu directives.