has_trivial_destructor improvable?

[Hite, Christopher]

Hi, does has_trivial_destructor<> and co depend on compiler magic?

Is it possible to detect empty deconstructors/constructors.  The reason I ask is because I'd like to make better placeholders for a boost::optional implementation using new unions from N2544.

template<typename T>
union placeholder{
	T v;
	placeholder() {}   // breaks has_trivial_constructor
	~placeholder (){} // breaks has_trivial_destructor
};

Is improving these possible or is there some conceptual problem with a circular reference?

Chris