c – boost :: serialization：具有私有默认构造函数的对象在向

#include <boost/serialization/nvp.hpp>
#include <boost/archive/xml_iarchive.hpp>
#include <boost/archive/xml_oarchive.hpp>

class Foo{
    friend class boost::serialization::access;
    template<class Archive>
    void serialize(Archive & ar,const unsigned int)
    {
        ar & BOOST_SERIALIZATION_NVP(i);
    }
    int i;
    Foo():i(0){}
public:
    Foo(int k):i(k){}
};

int main(int argc,char *argv[])
{
    std::vector< Foo> f;
    f.push_back(Foo(12));
    std::ofstream os("path");
    boost::archive::xml_oarchive oa(os);
    oa << boost::serialization::make_nvp("f",f);
    os.close();
    std::vector<Foo> g;
    std::ifstream is("path");
    boost::archive::xml_iarchive ia(is);
    ia >> boost::serialization::make_nvp("f",g);
}

这在序列化Foos矢量时工作正常.但是,如果我尝试序列化Foos的映射,它在私有默认构造函数上失败：

std::map<std::string,Foo> f;
f.insert(std::make_pair("hello",Foo(12)));
std::ofstream os("path");
boost::archive::xml_oarchive oa(os);
oa << boost::serialization::make_nvp("f",f);
os.close();
std::map<std::string,Foo> g;
std::ifstream is("path");
boost::archive::xml_iarchive ia(is);
ia >> boost::serialization::make_nvp("f",g);

失败了

In file included from main.cpp:2:
In file included from /usr/local/include/boost/serialization/nvp.hpp:19:
In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/utility:70:
/usr/bin/../lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/bits/stl_pair.h:109:18: error: field of type 'Foo' has private default constructor
      : first(),second() { }
                 ^
/usr/local/include/boost/serialization/access.hpp:132:17: note: in instantiation of member function 'std::pair<const std::basic_string<char>,Foo>::pair' requested here
        ::new(t)T;
                ^
/usr/local/include/boost/serialization/serialization.hpp:93:13: note: in instantiation of function template specialization 'boost::serialization::access::construct<std::pair<const std::basic_string<char>,Foo> >' requested here
    access::construct(t);
            ^
/usr/local/include/boost/serialization/serialization.hpp:158:9: note: in instantiation of function template specialization 'boost::serialization::load_construct_data<boost::archive::xml_iarchive,std::pair<const std::basic_string<char>,Foo> >' requested here
        load_construct_data(ar,t,v);
        ^
/usr/local/include/boost/serialization/detail/stack_constructor.hpp:58:31: note: in instantiation of function template specialization 'boost::serialization::load_construct_data_adl<boost::archive::xml_iarchive,Foo> >' requested here
        boost::serialization::load_construct_data_adl(
                              ^
/usr/local/include/boost/serialization/collections_load_imp.hpp:83:48: note: in instantiation of member function 'boost::serialization::detail::stack_construct<boost::archive::xml_iarchive,Foo> >::stack_construct' requested here
        detail::stack_construct<Archive,type> t(ar,v);
                                               ^
/usr/local/include/boost/serialization/collections_load_imp.hpp:158:16: note: (skipping 12 contexts in backtrace; use -ftemplate-backtrace-limit=0 to see all)
        hint = ifunc(ar,s,item_version,hint);
               ^
/usr/local/include/boost/archive/detail/common_iarchive.hpp:66:18: note: in instantiation of function template specialization 'boost::archive::load<boost::archive::xml_iarchive,std::map<std::basic_string<char>,Foo,std::less<std::basic_string<char> >,std::allocator<std::pair<const std::basic_string<char>,Foo> > > >' requested here
        archive::load(* this->This(),t);
                 ^
/usr/local/include/boost/archive/basic_xml_iarchive.hpp:86:39: note: in instantiation of function template specialization 'boost::archive::detail::common_iarchive<boost::archive::xml_iarchive>::load_override<std::map<std::basic_string<char>,Foo> > > >' requested here
        this->detail_common_iarchive::load_override(t.value(),0);
                                      ^
/usr/local/include/boost/archive/xml_iarchive.hpp:93:38: note: in instantiation of function template specialization 'boost::archive::basic_xml_iarchive<boost::archive::xml_iarchive>::load_override<std::map<std::basic_string<char>,Foo> > > >' requested here
        basic_xml_iarchive<Archive>::load_override(t,0);
                                     ^
/usr/local/include/boost/archive/detail/interface_iarchive.hpp:60:23: note: in instantiation of function template specialization 'boost::archive::xml_iarchive_impl<boost::archive::xml_iarchive>::load_override<const boost::serialization::nvp<std::map<std::basic_string<char>,Foo> > > > >' requested here
        this->This()->load_override(t,0);
                      ^
main.cpp:50:8: note: in instantiation of function template specialization 'boost::archive::detail::interface_iarchive<boost::archive::xml_iarchive>::operator>><const boost::serialization::nvp<std::map<std::basic_string<char>,Foo> > > > >' requested here
    ia >> boost::serialization::make_nvp("f",g);
       ^
main.cpp:34:5: note: implicitly declared private here
    Foo():i(0){}
    ^

我正在使用clang
Ubuntu clang版本3.4-1ubuntu3(标签/ RELEASE_34 / final)(基于LLVM 3.4)

和Ubuntu 14.04LTS一起提供1.55版本.

我试过提供load_construct_data()函数,如下所示：

namespace boost
{
    namespace serialization
    {
        template<class Archive>
        inline void load_construct_data(Archive &archive,Foo*a,unsigned int
file_version)
        {
            ::new(a)Foo(0);
        }
    }
}

但我仍然得到相同的错误,因为它在实例化std :: pair时需要构造函数