Hello, I have a class hierarchy that looks like this : class A {/**/}; // Polymorphic class B1 : virtual public A {/**/}; class B2 : virtual public A {/**/}; class C : public B1, public B2 {/**/}; class D : public C {/**/}; In C, I define the serialize function like this : template <class Archive> void C::serialize(Archive &ar, const unsigned int version) { BOOST_SERIALIZATION_BASE_OBJECT_NVP(B1); BOOST_SERIALIZATION_BASE_OBJECT_NVP(B2); // serialize fields specific to C } When I try to serialize an object of type C, it works just fine. However, when I try to serialize an object of class D, it fails. I have not yet tried to reproduce this problem in fully a toy example, but I'm going to do so ASAP. I'm using VC++8.0. When I try to debug the system, here is the information I get : At one time, I'm in save_pointer_type<xml_oarchive, A*> polymorphic::save in line vp = serialization::void_downcast(*true_type, *this_type, &t); At that place, when I inspect t, all is fine (especially the vfprt). Then I go in this void_downcast, where I can't inspect data, since the pointer has been cast to a void type. Next time I gets back some type info, i when calling : void_downcast( const extended_type_info & derived_type, // D const extended_type_info & base_type, // A const void * const t, bool top) In this function, I get an iterator at some point void_cast_detail::void_caster_registry::const_iterator it; That has the following content: Derived == D, Base == C. Then, it calls void_caster_primitive::downcast with those informations, where it calls boost::smart_cast<const Derived *, const Base *>( static_cast<const Base *>(t) // Derived == D, Base == C However, in this function, declared that way: template<class T, class U> T smart_cast(U u); If I try to look at the content of u, it seems totally broken. For instance, the vfptr contains values such as 0xcdcdcdcd 0x00000000 ... From my (limited) understanding of C++, casting from A* to void* and back to C* is not supposed to work, but I'd like some confirmation. Does someone have any idea about this problem, and if there is a workaround ? Best regards, -- Loïc