// g++-10 -std=c++2a
#include <boost/unordered/unordered_set.hpp>
#include <iterator>

int main()
{
    boost::unordered_multiset<std::string> a, b;
    b.insert(std::make_move_iterator(a.begin()), std::make_move_iterator(b.begin()));
}


```
In file included from /opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/stl_iterator_base_types.h:71,
                 from /opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/stl_algobase.h:65,
                 from /opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/array:40,
                 from /opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/tuple:39,
                 from /opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/functional:54,
                 from /opt/compiler-explorer/libs/boost_1_75_0/boost/container_hash/hash.hpp:20,
                 from /opt/compiler-explorer/libs/boost_1_75_0/boost/functional/hash.hpp:6,
                 from /opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:18,
                 from <source>:1:
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h: In substitution of 'template<class _Tp> using __iter_value_t = typename std::__detail::__iter_traits_impl<_Tp, std::indirectly_readable_traits<_Iter> >::type::value_type [with _Tp = boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > >]':
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h:259:11:   required by substitution of 'template<class _Tp> using iter_value_t = std::__detail::__iter_value_t<typename std::remove_cv<typename std::remove_reference<_Tp>::type>::type> [with _Tp = boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > >]'
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/stl_iterator.h:1301:13:   required from 'class std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >'
<source>:7:47:   required from here
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h:254:13: error: ambiguous template instantiation for 'struct std::indirectly_readable_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >'
  254 |       using __iter_value_t = typename
      |             ^~~~~~~~~~~~~~
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h:242:12: note: candidates are: 'template<class _Tp>  requires requires{typename _Tp::value_type;} struct std::indirectly_readable_traits<_Iter> [with _Tp = boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > >]'
  242 |     struct indirectly_readable_traits<_Tp>
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h:247:12: note:                 'template<class _Tp>  requires requires{typename _Tp::element_type;} struct std::indirectly_readable_traits<_Iter> [with _Tp = boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > >]'
  247 |     struct indirectly_readable_traits<_Tp>
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h:254:13: error: invalid use of incomplete type 'std::__detail::__iter_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > >, std::indirectly_readable_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > > >' {aka 'struct std::indirectly_readable_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >'}
  254 |       using __iter_value_t = typename
      |             ^~~~~~~~~~~~~~
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h:225:29: note: declaration of 'std::__detail::__iter_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > >, std::indirectly_readable_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > > >' {aka 'struct std::indirectly_readable_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >'}
  225 |   template<typename> struct indirectly_readable_traits { };
      |                             ^~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/set.hpp:6,
                 from /opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:20,
                 from <source>:1:
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp: In instantiation of 'struct boost::unordered::detail::is_forward<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > > >':
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:273:14:   required from 'struct boost::unordered::detail::disable_if_forward<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >, void*>'
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4364:14:   required by substitution of 'template<class I> void boost::unordered::detail::table<boost::unordered::detail::set<std::allocator<std::__cxx11::basic_string<char> >, std::__cxx11::basic_string<char>, boost::hash<std::__cxx11::basic_string<char> >, std::equal_to<std::__cxx11::basic_string<char> > > >::insert_range_equiv<I>(I, I, typename boost::unordered::detail::disable_if_forward<I, void*>::type) [with I = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >]'
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:1714:32:   required from 'void boost::unordered::unordered_multiset<T, H, P, A>::insert(InputIt, InputIt) [with InputIt = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >; T = std::__cxx11::basic_string<char>; H = boost::hash<std::__cxx11::basic_string<char> >; P = std::equal_to<std::__cxx11::basic_string<char> >; A = std::allocator<std::__cxx11::basic_string<char> >]'
<source>:7:84:   required from here
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:260:14: error: no type named 'iterator_category' in 'struct std::iterator_traits<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > > >'
  260 |       struct is_forward : boost::is_base_of<std::forward_iterator_tag,
      |              ^~~~~~~~~~
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp: In instantiation of 'struct boost::unordered::detail::disable_if_forward<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >, void*>':
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4364:14:   required by substitution of 'template<class I> void boost::unordered::detail::table<boost::unordered::detail::set<std::allocator<std::__cxx11::basic_string<char> >, std::__cxx11::basic_string<char>, boost::hash<std::__cxx11::basic_string<char> >, std::equal_to<std::__cxx11::basic_string<char> > > >::insert_range_equiv<I>(I, I, typename boost::unordered::detail::disable_if_forward<I, void*>::type) [with I = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >]'
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:1714:32:   required from 'void boost::unordered::unordered_multiset<T, H, P, A>::insert(InputIt, InputIt) [with InputIt = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >; T = std::__cxx11::basic_string<char>; H = boost::hash<std::__cxx11::basic_string<char> >; P = std::equal_to<std::__cxx11::basic_string<char> >; A = std::allocator<std::__cxx11::basic_string<char> >]'
<source>:7:84:   required from here
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:273:14: error: 'value' is not a member of 'boost::unordered::detail::is_forward<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > > >'
  273 |       struct disable_if_forward
      |              ^~~~~~~~~~~~~~~~~~
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp: In instantiation of 'struct boost::unordered::detail::enable_if_forward<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >, void*>':
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4340:14:   required by substitution of 'template<class I> void boost::unordered::detail::table<boost::unordered::detail::set<std::allocator<std::__cxx11::basic_string<char> >, std::__cxx11::basic_string<char>, boost::hash<std::__cxx11::basic_string<char> >, std::equal_to<std::__cxx11::basic_string<char> > > >::insert_range_equiv<I>(I, I, typename boost::unordered::detail::enable_if_forward<I, void*>::type) [with I = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >]'
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:1714:32:   required from 'void boost::unordered::unordered_multiset<T, H, P, A>::insert(InputIt, InputIt) [with InputIt = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >; T = std::__cxx11::basic_string<char>; H = boost::hash<std::__cxx11::basic_string<char> >; P = std::equal_to<std::__cxx11::basic_string<char> >; A = std::allocator<std::__cxx11::basic_string<char> >]'
<source>:7:84:   required from here
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:266:14: error: 'value' is not a member of 'boost::unordered::detail::is_forward<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > > >'
  266 |       struct enable_if_forward
      |              ^~~~~~~~~~~~~~~~~
In file included from <source>:1:
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp: In instantiation of 'void boost::unordered::unordered_multiset<T, H, P, A>::insert(InputIt, InputIt) [with InputIt = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >; T = std::__cxx11::basic_string<char>; H = boost::hash<std::__cxx11::basic_string<char> >; P = std::equal_to<std::__cxx11::basic_string<char> >; A = std::allocator<std::__cxx11::basic_string<char> >]':
<source>:7:84:   required from here
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:1714:32: error: no matching function for call to 'boost::unordered::detail::table<boost::unordered::detail::set<std::allocator<std::__cxx11::basic_string<char> >, std::__cxx11::basic_string<char>, boost::hash<std::__cxx11::basic_string<char> >, std::equal_to<std::__cxx11::basic_string<char> > > >::insert_range_equiv(std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >&, std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >&)'
 1714 |       table_.insert_range_equiv(first, last);
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
In file included from /opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/set.hpp:6,
                 from /opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:20,
                 from <source>:1:
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4340:14: note: candidate: 'template<class I> void boost::unordered::detail::table<Types>::insert_range_equiv(I, I, typename boost::unordered::detail::enable_if_forward<I, void*>::type) [with I = I; Types = boost::unordered::detail::set<std::allocator<std::__cxx11::basic_string<char> >, std::__cxx11::basic_string<char>, boost::hash<std::__cxx11::basic_string<char> >, std::equal_to<std::__cxx11::basic_string<char> > >]'
 4340 |         void insert_range_equiv(I i, I j,
      |              ^~~~~~~~~~~~~~~~~~
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4340:14: note:   substitution of deduced template arguments resulted in errors seen above
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4364:14: note: candidate: 'template<class I> void boost::unordered::detail::table<Types>::insert_range_equiv(I, I, typename boost::unordered::detail::disable_if_forward<I, void*>::type) [with I = I; Types = boost::unordered::detail::set<std::allocator<std::__cxx11::basic_string<char> >, std::__cxx11::basic_string<char>, boost::hash<std::__cxx11::basic_string<char> >, std::equal_to<std::__cxx11::basic_string<char> > >]'
 4364 |         void insert_range_equiv(I i, I j,
      |              ^~~~~~~~~~~~~~~~~~
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4364:14: note:   substitution of deduced template arguments resulted in errors seen above
ASM generation compiler returned: 1
In file included from /opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/stl_iterator_base_types.h:71,
                 from /opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/stl_algobase.h:65,
                 from /opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/array:40,
                 from /opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/tuple:39,
                 from /opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/functional:54,
                 from /opt/compiler-explorer/libs/boost_1_75_0/boost/container_hash/hash.hpp:20,
                 from /opt/compiler-explorer/libs/boost_1_75_0/boost/functional/hash.hpp:6,
                 from /opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:18,
                 from <source>:1:
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h: In substitution of 'template<class _Tp> using __iter_value_t = typename std::__detail::__iter_traits_impl<_Tp, std::indirectly_readable_traits<_Iter> >::type::value_type [with _Tp = boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > >]':
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h:259:11:   required by substitution of 'template<class _Tp> using iter_value_t = std::__detail::__iter_value_t<typename std::remove_cv<typename std::remove_reference<_Tp>::type>::type> [with _Tp = boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > >]'
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/stl_iterator.h:1301:13:   required from 'class std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >'
<source>:7:47:   required from here
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h:254:13: error: ambiguous template instantiation for 'struct std::indirectly_readable_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >'
  254 |       using __iter_value_t = typename
      |             ^~~~~~~~~~~~~~
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h:242:12: note: candidates are: 'template<class _Tp>  requires requires{typename _Tp::value_type;} struct std::indirectly_readable_traits<_Iter> [with _Tp = boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > >]'
  242 |     struct indirectly_readable_traits<_Tp>
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h:247:12: note:                 'template<class _Tp>  requires requires{typename _Tp::element_type;} struct std::indirectly_readable_traits<_Iter> [with _Tp = boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > >]'
  247 |     struct indirectly_readable_traits<_Tp>
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h:254:13: error: invalid use of incomplete type 'std::__detail::__iter_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > >, std::indirectly_readable_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > > >' {aka 'struct std::indirectly_readable_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >'}
  254 |       using __iter_value_t = typename
      |             ^~~~~~~~~~~~~~
/opt/compiler-explorer/gcc-10.3.0/include/c++/10.3.0/bits/iterator_concepts.h:225:29: note: declaration of 'std::__detail::__iter_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > >, std::indirectly_readable_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > > >' {aka 'struct std::indirectly_readable_traits<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >'}
  225 |   template<typename> struct indirectly_readable_traits { };
      |                             ^~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/set.hpp:6,
                 from /opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:20,
                 from <source>:1:
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp: In instantiation of 'struct boost::unordered::detail::is_forward<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > > >':
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:273:14:   required from 'struct boost::unordered::detail::disable_if_forward<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >, void*>'
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4364:14:   required by substitution of 'template<class I> void boost::unordered::detail::table<boost::unordered::detail::set<std::allocator<std::__cxx11::basic_string<char> >, std::__cxx11::basic_string<char>, boost::hash<std::__cxx11::basic_string<char> >, std::equal_to<std::__cxx11::basic_string<char> > > >::insert_range_equiv<I>(I, I, typename boost::unordered::detail::disable_if_forward<I, void*>::type) [with I = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >]'
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:1714:32:   required from 'void boost::unordered::unordered_multiset<T, H, P, A>::insert(InputIt, InputIt) [with InputIt = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >; T = std::__cxx11::basic_string<char>; H = boost::hash<std::__cxx11::basic_string<char> >; P = std::equal_to<std::__cxx11::basic_string<char> >; A = std::allocator<std::__cxx11::basic_string<char> >]'
<source>:7:84:   required from here
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:260:14: error: no type named 'iterator_category' in 'struct std::iterator_traits<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > > >'
  260 |       struct is_forward : boost::is_base_of<std::forward_iterator_tag,
      |              ^~~~~~~~~~
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp: In instantiation of 'struct boost::unordered::detail::disable_if_forward<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >, void*>':
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4364:14:   required by substitution of 'template<class I> void boost::unordered::detail::table<boost::unordered::detail::set<std::allocator<std::__cxx11::basic_string<char> >, std::__cxx11::basic_string<char>, boost::hash<std::__cxx11::basic_string<char> >, std::equal_to<std::__cxx11::basic_string<char> > > >::insert_range_equiv<I>(I, I, typename boost::unordered::detail::disable_if_forward<I, void*>::type) [with I = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >]'
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:1714:32:   required from 'void boost::unordered::unordered_multiset<T, H, P, A>::insert(InputIt, InputIt) [with InputIt = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >; T = std::__cxx11::basic_string<char>; H = boost::hash<std::__cxx11::basic_string<char> >; P = std::equal_to<std::__cxx11::basic_string<char> >; A = std::allocator<std::__cxx11::basic_string<char> >]'
<source>:7:84:   required from here
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:273:14: error: 'value' is not a member of 'boost::unordered::detail::is_forward<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > > >'
  273 |       struct disable_if_forward
      |              ^~~~~~~~~~~~~~~~~~
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp: In instantiation of 'struct boost::unordered::detail::enable_if_forward<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >, void*>':
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4340:14:   required by substitution of 'template<class I> void boost::unordered::detail::table<boost::unordered::detail::set<std::allocator<std::__cxx11::basic_string<char> >, std::__cxx11::basic_string<char>, boost::hash<std::__cxx11::basic_string<char> >, std::equal_to<std::__cxx11::basic_string<char> > > >::insert_range_equiv<I>(I, I, typename boost::unordered::detail::enable_if_forward<I, void*>::type) [with I = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >]'
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:1714:32:   required from 'void boost::unordered::unordered_multiset<T, H, P, A>::insert(InputIt, InputIt) [with InputIt = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >; T = std::__cxx11::basic_string<char>; H = boost::hash<std::__cxx11::basic_string<char> >; P = std::equal_to<std::__cxx11::basic_string<char> >; A = std::allocator<std::__cxx11::basic_string<char> >]'
<source>:7:84:   required from here
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:266:14: error: 'value' is not a member of 'boost::unordered::detail::is_forward<std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > > >'
  266 |       struct enable_if_forward
      |              ^~~~~~~~~~~~~~~~~
In file included from <source>:1:
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp: In instantiation of 'void boost::unordered::unordered_multiset<T, H, P, A>::insert(InputIt, InputIt) [with InputIt = std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >; T = std::__cxx11::basic_string<char>; H = boost::hash<std::__cxx11::basic_string<char> >; P = std::equal_to<std::__cxx11::basic_string<char> >; A = std::allocator<std::__cxx11::basic_string<char> >]':
<source>:7:84:   required from here
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:1714:32: error: no matching function for call to 'boost::unordered::detail::table<boost::unordered::detail::set<std::allocator<std::__cxx11::basic_string<char> >, std::__cxx11::basic_string<char>, boost::hash<std::__cxx11::basic_string<char> >, std::equal_to<std::__cxx11::basic_string<char> > > >::insert_range_equiv(std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >&, std::move_iterator<boost::unordered::iterator_detail::c_iterator<boost::unordered::detail::ptr_node<std::__cxx11::basic_string<char> > > >&)'
 1714 |       table_.insert_range_equiv(first, last);
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
In file included from /opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/set.hpp:6,
                 from /opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/unordered_set.hpp:20,
                 from <source>:1:
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4340:14: note: candidate: 'template<class I> void boost::unordered::detail::table<Types>::insert_range_equiv(I, I, typename boost::unordered::detail::enable_if_forward<I, void*>::type) [with I = I; Types = boost::unordered::detail::set<std::allocator<std::__cxx11::basic_string<char> >, std::__cxx11::basic_string<char>, boost::hash<std::__cxx11::basic_string<char> >, std::equal_to<std::__cxx11::basic_string<char> > >]'
 4340 |         void insert_range_equiv(I i, I j,
      |              ^~~~~~~~~~~~~~~~~~
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4340:14: note:   substitution of deduced template arguments resulted in errors seen above
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4364:14: note: candidate: 'template<class I> void boost::unordered::detail::table<Types>::insert_range_equiv(I, I, typename boost::unordered::detail::disable_if_forward<I, void*>::type) [with I = I; Types = boost::unordered::detail::set<std::allocator<std::__cxx11::basic_string<char> >, std::__cxx11::basic_string<char>, boost::hash<std::__cxx11::basic_string<char> >, std::equal_to<std::__cxx11::basic_string<char> > >]'
 4364 |         void insert_range_equiv(I i, I j,
      |              ^~~~~~~~~~~~~~~~~~
/opt/compiler-explorer/libs/boost_1_75_0/boost/unordered/detail/implementation.hpp:4364:14: note:   substitution of deduced template arguments resulted in errors seen above
Execution build compiler returned: 1
```

It works on 9 and 11 though. Could a fix be backported to 10?

https://godbolt.org/z/Mzd3TaM4Y