#include <boost/serialization/base_object.hpp>
#include <boost/serialization/nvp.hpp>
using boost::serialization::make_nvp;

class B 
{
public:
    virtual ~B() {}
    template<class Archive>
    void serialize(Archive& ar, unsigned int version)
    {
        ar & make_nvp("i", i);
    }
    int i;
};

class D : public B {
public:
    template<class Archive>
    void serialize(Archive& ar, unsigned int)
    {
        ar & boost::serialization::base_object<B>(*this);
    }
};