I don't understand why this simple test doesn't compile. Any hints? #include <iostream> #include <sstream> #include <boost/archive/binary_oarchive.hpp> #include <boost/archive/binary_iarchive.hpp> class rng_t { public: friend class boost::serialization::access; // BOOST_SERIALIZATION_SPLIT_MEMBER() template<class Archive> inline void save (Archive &ar, const unsigned int) const { for (int j = 0; j < 10; ++j) // ar << compute(j); ar << int(0); } template<class Archive> inline void load (Archive &ar, const unsigned int) { } template<class Archive> void serialize(Archive & ar, const unsigned int file_version) { boost::serialization::split_member(ar, *this, file_version); } }; void getstate (const rng_t& rng) { std::ostringstream os; boost::archive::binary_oarchive oa(os); oa << rng; } void setstate (rng_t& rng, std::string& st) { std::istringstream is (st); boost::archive::binary_iarchive ia (is); ia >> rng; } g++ -c test.cc test.cc: In member function ‘void rng_t::save(Archive&, unsigned int) const [with Archive = boost::archive::binary_oarchive]’: /usr/include/boost/serialization/access.hpp:93: instantiated from ‘static void boost::serialization::access::member_save(Archive&, T&, unsigned int) [with Archive = boost::archive::binary_oarchive, T = const rng_t]’ /usr/include/boost/serialization/split_member.hpp:43: instantiated from ‘static void boost::serialization::detail::member_saver<Archive, T>::invoke(Archive&, const T&, unsigned int) [with Archive = boost::archive::binary_oarchive, T = rng_t]’ /usr/include/boost/serialization/split_member.hpp:69: instantiated from ‘void boost::serialization::split_member(Archive&, T&, unsigned int) [with Archive = boost::archive::binary_oarchive, T = rng_t]’ test.cc:25: instantiated from ‘void rng_t::serialize(Archive&, unsigned int) [with Archive = boost::archive::binary_oarchive]’ /usr/include/boost/serialization/access.hpp:109: instantiated from ‘static void boost::serialization::access::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::binary_oarchive, T = rng_t]’ /usr/include/boost/serialization/serialization.hpp:81: instantiated from ‘void boost::serialization::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::binary_oarchive, T = rng_t]’ /usr/include/boost/serialization/serialization.hpp:140: instantiated from ‘void boost::serialization::serialize_adl(Archive&, T&, unsigned int) [with Archive = boost::archive::binary_oarchive, T = rng_t]’ /usr/include/boost/archive/detail/oserializer.hpp:147: instantiated from ‘void boost::archive::detail::oserializer<Archive, T>::save_object_data(boost::archive::detail::basic_oarchive&, const void*) const [with Archive = boost::archive::binary_oarchive, T = rng_t]’ test.cc:37: instantiated from here test.cc:16: error: no match for ‘operator<<’ in ‘ar << 0’ /usr/include/boost/archive/detail/interface_oarchive.hpp:84: note: candidates are: Archive& boost::archive::detail::interface_oarchive<Archive>::operator<<(T&) [with T = int, Archive = boost::archive::binary_oarchive]