[Boost-users] Problems with nesting boost::container::small_vector and C++98

Subject: [Boost-users] Problems with nesting boost::container::small_vector and C++98
From: Daniel Trstenjak (daniel.trstenjak_at_[hidden])
Date: 2016-12-31 11:44:02

Hi,

first the used versions:
   boost 1.63.0
   gcc 5.4.0 20160609
   Ubuntu 16.04.1

the example I've problems with is:

   #include <map>
   #include <boost/container/small_vector.hpp>
   
   using boost::container::small_vector;
   
   typedef std::pair<int, small_vector<float, 8> > mypair;
   
   typedef std::map<int, mypair> mymap;
   typedef std::map<int, small_vector<mypair, 8> > mymap2;
   typedef std::map<int, small_vector<small_vector<float, 8>, 8> > mymap3;
   
   int main()
   {
      mymap m;
      mypair& sv = m[0];
   
      mymap2 m2;
      small_vector<mypair, 8>& sv2 = m2[0];
   
      mymap3 m3;
      small_vector<small_vector<float, 8>, 8>& sv3 = m3[0];
   }

I can compile it without errors with 'g++ -std=c++11', but without
'-std=c++11' I'm getting an error for the 'operator[]' on mymap2:

dan_at_octa ~> g++ -Iboost_1_63_0/ small_vector_test.cpp 
In file included from boost_1_63_0/boost/container/small_vector.hpp:27:0,
                 from small_vector_test.cpp:2:
boost_1_63_0/boost/container/vector.hpp: In instantiation of ‘void boost::container::vector<T, Allocator>::assign(FwdIt, FwdIt, typename boost::move_detail::disable_if_or<void, boost::move_detail::is_same<typename boost::container::container_detail::version<Allocator>::type, boost::move_detail::integral_constant<unsigned int, 0u> >, boost::move_detail::is_convertible<InIt, typename boost::container::allocator_traits<Allocator>::size_type>, boost::container::container_detail::is_input_iterator<FwdIt> >::type*) [with FwdIt = boost::container::container_detail::vec_iterator<std::pair<int, boost::container::small_vector<float, 8ul> >*, true>; T = std::pair<int, boost::container::small_vector<float, 8ul> >; Allocator = boost::container::small_vector_allocator<boost::container::new_allocator<std::pair<int, boost::container::small_vector<float, 8ul> > > >; typename boost::move_detail::disable_if_or<void, boost::move_detail::is_same<typename boost::container::container_detail::version<Allocator>::type, boost::move_detail::integral_constant<unsigned int, 0u> >, boost::move_detail::is_convertible<InIt, typename boost::container::allocator_traits<Allocator>::size_type>, boost::container::container_detail::is_input_iterator<FwdIt> >::type = void]’:
boost_1_63_0/boost/container/small_vector.hpp:563:7:   required from ‘boost::container::small_vector<T, N, Allocator>::small_vector(const boost::container::small_vector<T, N, Allocator>&) [with T = std::pair<int, boost::container::small_vector<float, 8ul> >; long unsigned int N = 8ul; Allocator = boost::container::new_allocator<std::pair<int, boost::container::small_vector<float, 8ul> > >]’
/usr/include/c++/5/bits/stl_pair.h:113:31:   required from ‘std::pair<_T1, _T2>::pair(const _T1&, const _T2&) [with _T1 = const int; _T2 = boost::container::small_vector<std::pair<int, boost::container::small_vector<float, 8ul> >, 8ul>]’
/usr/include/c++/5/bits/stl_map.h:487:23:   required from ‘std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const key_type&) [with _Key = int; _Tp = boost::container::small_vector<std::pair<int, boost::container::small_vector<float, 8ul> >, 8ul>; _Compare = std::less<int>; _Alloc = std::allocator<std::pair<const int, boost::container::small_vector<std::pair<int, boost::container::small_vector<float, 8ul> >, 8ul> > >; std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type = boost::container::small_vector<std::pair<int, boost::container::small_vector<float, 8ul> >, 8ul>; std::map<_Key, _Tp, _Compare, _Alloc>::key_type = int]’
small_vector_test.cpp:18:39:   required from here
boost_1_63_0/boost/container/vector.hpp:1261:15: error: binding ‘const std::pair<int, boost::container::small_vector<float, 8ul> >’ to reference of type ‘std::pair<int, boost::container::small_vector<float, 8ul> >&’ discards qualifiers
          *cur = *first;
               ^
In file included from /usr/include/c++/5/bits/stl_algobase.h:64:0,
                 from /usr/include/c++/5/bits/stl_tree.h:63,
                 from /usr/include/c++/5/map:60,
                 from small_vector_test.cpp:1:
/usr/include/c++/5/bits/stl_pair.h:96:12: note:   initializing argument 1 of ‘std::pair<int, boost::container::small_vector<float, 8ul> >& std::pair<int, boost::container::small_vector<float, 8ul> >::operator=(std::pair<int, boost::container::small_vector<float, 8ul> >&)’
     struct pair
            ^

Any ideas?
Is 'boost:container::small_vector' supposed to work without C++11 support?

Thanks!

Greetings,
Daniel