In http://www.boost.org/doc/libs/1_54_0/libs/serialization/doc/index.html:
By default, data types designated primitive by Implementation Level class serialization trait are never tracked. If it is desired to track a shared primitive object through a pointer (e.g. a long used as a reference count), It should be wrapped in a class/struct so that it is an identifiable type. The alternative of changing the implementation level of a long would affect all longs serialized in the whole program - probably not what one would intend.
Hence:
struct Wrapped {
int value;
private:
friend class boost::serialization::access;
template<class Archive>
void serialize(Archive & ar,const unsigned int file_version)
{
ar & value;
}
};
boost::shared_ptr<Wrapped> sp;
Wrapped const * p;