[boost] is_convertible: bug or missing feature?

From: Gennadiy Rozental (rogeeff_at_[hidden])
Date: 2002-05-09 21:34:22

Hi,

Look at the following example:

#include <boost/type_traits/conversion_traits.hpp>
template<typename T>
struct A : T
{
    A()                                              {}
    template<class T1>
    A( A<T1> const& rhs ) : T( rhs ) {}
};

struct B {};
struct C {};

int main() {
    bool bb = boost::is_convertible<A<B>,A<C> >::value; // here value bb is
true, while I expext it will be false
    return 0;
}

With MSVC 6.5 I have got incorrect value bb - true.
Why?
Is it is_convertible bug?
Is it missing feature in is_convertible implementation?
Is it bug in MSVC?
Is it impossible to implement correctly?

If it last, is there other way to perform this check.

Regards,

Gennadiy.