id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
2271	Cannot load version 1.35.0 xml archives that contain vectors of primitive types	Ryan Mulder <rjmyst3@…>	Matthias Troyer	"Version 1.35.0 xml archives are missing the <item_version> element in vectors of primitive types.

This is obviously a known issue, because version 1.36.0 includes the compatibility header vector_135.hpp.

The problem is, that even when vector_135.hpp is included, it makes no difference because the appropriate load method is not called.

The load method in vector.hpp that is aware of the 1.35.0 bug is this:
{{{
template<class Archive, class U, class Allocator>
inline void load(
    Archive & ar,
    std::vector<U, Allocator> &t,
    const unsigned int /* file_version */,
    mpl::true_
){
    collection_size_type count(t.size());
    ar >> BOOST_SERIALIZATION_NVP(count);
    t.resize(count);
    unsigned int item_version=0;
    if(BOOST_SERIALIZATION_VECTOR_VERSION < ar.get_library_version())
        ar >> BOOST_SERIALIZATION_NVP(item_version);
    if (!t.empty())
      ar >> make_array(detail::get_data(t),t.size());
  }
}}}

It works correctly, when called.
The problem is that the load method which dispatches to either the default or the optimized version chooses the wrong version for vectors of primitive types.

{{{
template<class Archive, class U, class Allocator>
inline void load(
    Archive & ar,
    std::vector<U, Allocator> &t,
    const unsigned int file_version
){
	load(ar,t,file_version, BOOST_DEDUCED_TYPENAME use_array_optimization<Archive>::template apply<U>::type() );
}
}}}

For some reason, use_array_optimization does not work with primitive types.

Version 1.35.0 used boost::detail::has_default_constructor<U>() to dispatch.

My patch changes the dispatching load method to this:
{{{
template<class Archive, class U, class Allocator>
inline void load(
    Archive & ar,
    std::vector<U, Allocator> &t,
    const unsigned int file_version
){
	if(BOOST_SERIALIZATION_VECTOR_VERSION < ar.get_library_version())
	{
		load(ar,t,file_version, BOOST_DEDUCED_TYPENAME use_array_optimization<Archive>::template apply<U>::type() );
	}
	else
	{
		load(ar,t,file_version, boost::detail::has_default_constructor<U>() );		
	}
}
}}}

It works well, but I do not fully why use_array_optimization did not work alone.

I used a vector< unsigned char > as a test case."	Patches	closed	Boost 1.37.0	serialization	Boost 1.36.0	Problem	fixed