I may be wrong, but I thought it’s that you can’t have any fields with non trivial destructors, because the union wouldn’t know which destructor to call. So POD

I may be wrong, but I thought it’s that you can’t have any fields with non trivial destructors, because the union wouldn’t know which destructor to call. So POD types / raw pointers / arrays of the above / structs of the above are allowed, and that’s pretty much it.