[Boost-users] [serialize] using virtual inheritance causes compiler error

Subject: [Boost-users] [serialize] using virtual inheritance causes compiler error
From: Douwe Gelling (douwegelling_at_[hidden])
Date: 2016-10-26 11:45:05

Hi all,

When trying to serialize a class with a virtual base class, I'm getting
compilation errors. It seems to be part of a bug in type_traits, but I'm
wondering if anyone knows a workaround for making it work anyhow.

ultimately, the error boils down to "error: virtual function 'A::foo' has
more than one final overrider in 'boost_type_traits_internal_struct_X'",
using the code listing below..
It's simplified as much as possible, but obviously I need virtual
inheritance due to using diamond inheritance.

#include <boost/archive/text_oarchive.hpp>
#include <boost/serialization/base_object.hpp>
#include <boost/serialization/export.hpp>
#include <boost/serialization/serialization.hpp>

struct A
{
  virtual ~A(){};
  virtual void foo() = 0;
  template <class Archive>
  void serialize(Archive& ar, const unsigned int version)
  {
  }
};

struct B : public virtual A
{
  virtual void foo()
  {
  }
  template <class Archive>
  void serialize(Archive& ar, const unsigned int version)
  {
    ar& boost::serialization::base_object<A>(*this);
  }
};

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

BOOST_CLASS_EXPORT(C);

int main()
{
  C c;
  return 0;
}