#include <boost/type_traits/integral_constant.hpp>

void
f( ...)
{
}

struct udt
{
    static const bool value = true;
    operator bool() { return value; }
};

struct derived : udt {};

int
main(void)
{
    f( udt());
    f( derived());
    f( boost::integral_constant<bool,true>());
    return 0;
}