[Bug fortran/107000] ICE in gfc_real2complex, at fortran/arith.cc:2243

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107000

--- Comment #14 from anlauf at gcc dot gnu.org ---
(In reply to Mikael Morin from comment #13)
> If we pass this check, we proceed to reduce_binary, where if one (or both)
> of the operands is an array, we do numerical evaluation for every element of
> the array.
> 
> With the guarding check above, it is safe, with the assumption that elements
> of an array have the same type as the array itself.  If that condition is
> not true, well, it doesn't work obviously.
> 
> I don't see right now where an additional check would fit well, but the fix
> doesn't belong to walk_array_constructor in any case from my point of view.

We could walk through the elements of each array passed to reduce_binary
and check the types of the elements there, or do this check in a somewhat
more clever way than in the patch attached to comment#3.

This patch tried to perform checks in reduce_binary_ac, but I was not happy
with that particular implementation.

When looping over the elements, we currently have

      gfc_simplify_expr (c->expr, 0);

      if (c->expr->expr_type == EXPR_CONSTANT)
        rc = eval (c->expr, op2, &r);
      else
        rc = reduce_binary_ac (eval, c->expr, op2, &r);

and do not handle the case that c->expr->ts.type == BT_UNKNOWN.
Should we return sth. like rc = ARITH_INCOMMENSURATE, except that it is
not array .op. array?