Any thoughts from the type_traits authors?
I think decayed is an excellent trait. Your implementation should be modified to also take care of functions converting into function pointers though. It's a shame about the const qaulifier in your example make_pair messing up the int[10] conversion to int*.
I agree that it should work for function to function-pointer conversions as well. I've attached a slightly improved version that gets your non-const make_pair working, also uses remove_bounds rather than the range lib traits (just to keep things in the type_traits family). Not sure about the "decayed" name, but I can't think of anything better right now.
This is a characteristic of pair, not make_pair. And it could be disabled by restricting the member template constructor in:
template <class T1, class T2> struct pair { typedef T1 first_type; typedef T2 second_type;
T1 first; T2 second; pair(); pair(const T1& x, const T2& y); template<class U, class V> pair(const pair<U, V> &p); };
such that is_convertible<U, T1> and is_convertible<V, T2>, which is a change I would support.
If we do that, then we should do the same for the tuple constructors as well. John.