g++ and aliasing bools

[Joe Buck]

> I bootstrapped this version on sparc-sun-solaris2.8:
> 
> {
>   if (AGGREGATE_TYPE_P (t) &&
>       !((TREE_CODE (t) == RECORD_TYPE)
>         && !CLASSTYPE_NON_POD_P(t)
>         && !CLASSTYPE_N_BASECLASSES(t)))
>       return 0;
>   }

CLASSNAME_NON_POD_P returns false if there are any methods or if there
is a constructor or destructor, right?  If so, then I think we're going
to get little gain: much of the payoff from better aliasing in C++ will
come if we don't get false aliasing complaints for things like STL
iterators.  At least in my code, I don't have many NON_PODs; even if
it's a plain struct otherwise, I use a constructor to initialize it.

On the other hand, some of the STL iterators are derived classes.  Sigh.