[Bug c++/107295] [13 Regression] Rejected code in libreoffice with -m32 since r13-3290-g98e341130f87984a

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107295

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Ah, so that is a different issue then.
And with slightly modified testcase quite old one, which regressed with:
r8-727-g6b6ae9eb9c06b6911573bb9a13cf98b5a7c98b78
template <typename T> struct VecHelper {
  typedef T __attribute__((vector_size(sizeof(int)))) V;
};
template <int, typename T> using Vec = typename VecHelper<T>::V;
template <typename T> using V = Vec<4, T>;
using F = V<float>;
constexpr F F0 = F() + (float) 0.0L;
The problem is that the NOP_EXPR around long double REAL_CST has TREE_CONSTANT
flag and so the CONSTRUCTOR around it and thus we just fold the CONSTRUCTOR in:
    case CONSTRUCTOR:
      if (TREE_CONSTANT (t) && reduced_constant_expression_p (t))
        {
          /* Don't re-process a constant CONSTRUCTOR, but do fold it to
             VECTOR_CST if applicable.  */
          verify_constructor_flags (t);
          if (TREE_CONSTANT (t))
            return fold (t);
        }
      r = cxx_eval_bare_aggregate (ctx, t, lval,
                                   non_constant_p, overflow_p);
      break;
but that handles the case where it has REAL_CST elts, but doesn't handle the
case where it has NOP_EXPRs around them.
I wonder if we just shouldn't call cxx_eval_bare_aggregate always for
VECTOR_TYPE.