[Serialization] Strange giant warning
For a short while now I've been using boost serialization. It works perfectly... except... it keeps coming up one massive warning (that takes up ~100 lines). (see below) Whenever I get annoyed, I try to experiment and then search for answers online, but no luck. I'm probably using the library incorrectly somewhere. So I made a small program that generates the problem. Any advice on what I could be doing wrong would be appreciated. I use vc++ 2008 btw. Thanks. Code: -------------------------------------------- /* demonstration of problem. The program asks the user for a number, and then saves this number to a file. When the user returns, the number is remembered. */ #include <iostream> #include <fstream> #include <boost/serialization/shared_ptr.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> // save and load methods void save (const char * fname); bool load (const char * fname); // returns if successful // I know this is way too simple to put in a class, but bare with me class Game { public: Game () { number = 0; } void getNumberFromUser () { std::cin >> number; } int getNumber () { return number; } private: int number; friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & number; } }; typedef boost::shared_ptr< Game > Game_ptr; Game_ptr game; // entry int main () { game = Game_ptr( new Game ); // welcome std::cout << "Hello\n"; // if file exists, recall the number if (load ("save.txt")) std::cout << "You're number is " << game->getNumber() << ".\n"; // ask user for number std::cout << "Enter a number: \n"; game->getNumberFromUser (); // memorise number save ("save.txt"); // exit return 0; } void save (const char * fname) { std::ofstream ofs( fname ); boost::archive::text_oarchive oa( ofs ); // save oa << game; } bool load (const char * fname) { std::ifstream ifs( fname ); if (!ifs) return false; // file doesn't already exist boost::archive::text_iarchive ia( ifs ); // load ia >> game; // <------ Removing this line makes the warning go away return true; } Warning: -------------------------------------------- 1>main.cpp 1>d:\dev\boostpro\boost\boost_1_40\boost\serialization\extended_type_info_typeid.hpp(88) : warning C4099: 'boost::serialization::static_warning_impl<false>::STATIC_WARNING' : type name first seen using 'struct' now seen using 'class' 1> d:\dev\boostpro\boost\boost_1_40\boost\serialization\static_warning.hpp(115) : see declaration of 'boost::serialization::static_warning_impl<false>::STATIC_WARNING' 1> d:\dev\boostpro\boost\boost_1_40\boost\serialization\extended_type_info_typeid.hpp(85) : while compiling class template member function 'const boost::serialization::extended_type_info *boost::serialization::extended_type_info_typeid<T>::get_derived_extended_type_info(const T &) const' 1> with 1> [ 1> T=Game 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\archive\shared_ptr_helper.hpp(105) : see reference to class template instantiation 'boost::serialization::extended_type_info_typeid<T>' being compiled 1> with 1> [ 1> T=Game 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\serialization\shared_ptr.hpp(138) : see reference to function template instantiation 'void boost::archive::detail::shared_ptr_helper::reset<Game>(boost::shared_ptr<T> &,T *)' being compiled 1> with 1> [ 1> T=Game 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\serialization\split_free.hpp(58) : see reference to function template instantiation 'void boost::serialization::load<Archive,Game>(Archive &,boost::shared_ptr<T> &,const unsigned int)' being compiled 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\serialization\split_free.hpp(54) : while compiling class template member function 'void boost::serialization::free_loader<Archive,T>::invoke(Archive &,T &,const unsigned int)' 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=boost::shared_ptr<Game> 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\serialization\split_free.hpp(74) : see reference to class template instantiation 'boost::serialization::free_loader<Archive,T>' being compiled 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=boost::shared_ptr<Game> 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\serialization\shared_ptr.hpp(153) : see reference to function template instantiation 'void boost::serialization::split_free<Archive,boost::shared_ptr<T>>(Archive &,boost::shared_ptr<T> &,const unsigned int)' being compiled 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\serialization\serialization.hpp(133) : see reference to function template instantiation 'void boost::serialization::serialize<Archive,Game>(Archive &,boost::shared_ptr<T> &,const unsigned int)' being compiled 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\archive\detail\iserializer.hpp(174) : see reference to function template instantiation 'void boost::serialization::serialize_adl<Archive,T>(Archive &,T &,const unsigned int)' being compiled 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game_ptr 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\archive\detail\iserializer.hpp(161) : while compiling class template member function 'void boost::archive::detail::iserializer<Archive,T>::load_object_data(boost::archive::detail::basic_iarchive &,void *,const unsigned int) const' 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game_ptr 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\archive\detail\iserializer.hpp(362) : see reference to class template instantiation 'boost::archive::detail::iserializer<Archive,T>' being compiled 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game_ptr 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\archive\detail\iserializer.hpp(351) : while compiling class template member function 'void boost::archive::detail::load_non_pointer_type<Archive,T>::load_standard::invoke(Archive &,T &)' 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game_ptr 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\archive\detail\iserializer.hpp(417) : see reference to class template instantiation 'boost::archive::detail::load_non_pointer_type<Archive,T>::load_standard' being compiled 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game_ptr 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\archive\detail\iserializer.hpp(405) : while compiling class template member function 'void boost::archive::detail::load_non_pointer_type<Archive,T>::invoke(Archive &,T &)' 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game_ptr 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\archive\detail\iserializer.hpp(542) : see reference to class template instantiation 'boost::archive::detail::load_non_pointer_type<Archive,T>' being compiled 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game_ptr 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\archive\detail\common_iarchive.hpp(61) : see reference to function template instantiation 'void boost::archive::load<Archive,T>(Archive &,T &)' being compiled 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game_ptr 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\archive\basic_text_iarchive.hpp(62) : see reference to function template instantiation 'void boost::archive::detail::common_iarchive<Archive>::load_override<T>(T &,int)' being compiled 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game_ptr 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\archive\text_iarchive.hpp(66) : see reference to function template instantiation 'void boost::archive::basic_text_iarchive<Archive>::load_override<T>(T &,int)' being compiled 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game_ptr 1> ] 1> d:\dev\boostpro\boost\boost_1_40\boost\archive\detail\interface_iarchive.hpp(61) : see reference to function template instantiation 'void boost::archive::text_iarchive_impl<Archive>::load_override<T>(T &,int)' being compiled 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game_ptr 1> ] 1> d:\dev\visual studio 2008\projects\boostserialisation\boostserialisation\main.cpp(82) : see reference to function template instantiation 'Archive &boost::archive::detail::interface_iarchive<Archive>::operator >><Game_ptr>(T &)' being compiled 1> with 1> [ 1> Archive=boost::archive::text_iarchive, 1> T=Game_ptr 1> ]
2010/3/8 David <evildavo@gmail.com>
1>d:\dev\boostpro\boost\boost_1_40\boost\serialization\extended_type_info_typeid.hpp(88) : warning C4099: 'boost::serialization::static_warning_impl<false>::STATIC_WARNING' : type name first seen using 'struct' now seen using 'class'
Take a look at extended_type_info_typeid.hpp line 88. Roman Perepelitsa.
Nothing stands out to me. Polymorphic.... hmm... I don't do anything of the sort in my example. Doesn't really explain why the warning is there does it. So that readers can follow along... here's extended_type_info_typeid.hpp line 88: // get the eti record for the true type of this record // relying upon standard type info implemenation (rtti) const extended_type_info * get_derived_extended_type_info(const T & t) const { // note: this implementation - based on usage of typeid (rtti) // only does something if the class has at least one virtual function. BOOST_STATIC_WARNING(boost::is_polymorphic<T>::value); return detail::extended_type_info_typeid_0::get_extended_type_info( typeid(t) ); ----- Original Message ----- From: Roman Perepelitsa To: boost-users@lists.boost.org Sent: Tuesday, March 09, 2010 12:41 AM Subject: Re: [Boost-users] [Serialization] Strange giant warning 2010/3/8 David <evildavo@gmail.com> 1>d:\dev\boostpro\boost\boost_1_40\boost\serialization\extended_type_info_typeid.hpp(88) : warning C4099: 'boost::serialization::static_warning_impl<false>::STATIC_WARNING' : type name first seen using 'struct' now seen using 'class' Take a look at extended_type_info_typeid.hpp line 88. Roman Perepelitsa. ------------------------------------------------------------------------------ _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users
2010/3/8 David <evildavo@gmail.com>
Nothing stands out to me. Polymorphic.... hmm... I don't do anything of the sort in my example. Doesn't really explain why the warning is there does it.
What if someone implemented a class that inherits Game and serialized that to an archive? When reading shared_ptr<Game> from such an archive, serialization library does no know in advance which type should be used to create an object, hence the need for a type to be polymorphic. Adding a virtual function (e.g. destructor) fixes the problem for you? Roman Perepelitsa.
"David" <evildavo@gmail.com> wrote in message news:001401cabed0$fc9ea1d0$0300a8c0@pheonix... Nothing stands out to me. Polymorphic.... hmm... I don't do anything of the sort in my example. Doesn't really explain why the warning is there does it.
Out of curiosity, have you tried compiling this with boost 1.42?
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