# include <boost/iterator/iterator_facade.hpp>

struct s {};

template <class T, class U>
void implicit_cast(U) {}

struct iter :
    public boost::iterator_facade<
        iter
      , s
      , boost::forward_traversal_tag
    >
{
    void increment() {}
    bool equal(iter const&) const { return true; }
    s& dereference() const { return s_; }
    mutable s s_;
};

int main()
{
    iter i;
    i.operator->();
}