Build failure when using std::variant #24

tusooa · 2021-01-23T00:26:38Z

I got this build failure:

/usr/include/zug/sequence.hpp:225:47: error: wrong number of template arguments (1, should be at least 2)
  225 |                       std::decay_t<RangeTs>...>
      |                                               ^
/usr/include/zug/sequence.hpp:158:8: note: provided for ‘template<class ValueT, class XformT, class ... RangeTs> struct zug::sequence_range’
  158 | struct sequence_range
      |        ^~~~~~~~~~~~~~
/usr/include/zug/sequence.hpp:225:47: error: wrong number of template arguments (1, should be at least 2)
  225 |                       std::decay_t<RangeTs>...>
      |                                               ^
/usr/include/zug/sequence.hpp:158:8: note: provided for ‘template<class ValueT, class XformT, class ... RangeTs> struct zug::sequence_range’
  158 | struct sequence_range
      |        ^~~~~~~~~~~~~~
/usr/include/zug/sequence.hpp:225:47: error: wrong number of template arguments (1, should be at least 2)
  225 |                       std::decay_t<RangeTs>...>
      |                                               ^
/usr/include/zug/sequence.hpp:158:8: note: provided for ‘template<class ValueT, class XformT, class ... RangeTs> struct zug::sequence_range’
  158 | struct sequence_range
      |        ^~~~~~~~~~~~~~
/usr/include/zug/sequence.hpp:225:47: error: wrong number of template arguments (1, should be at least 2)
  225 |                       std::decay_t<RangeTs>...>
      |                                               ^
/usr/include/zug/sequence.hpp:158:8: note: provided for ‘template<class ValueT, class XformT, class ... RangeTs> struct zug::sequence_range’
  158 | struct sequence_range
      |        ^~~~~~~~~~~~~~
/usr/include/zug/sequence.hpp:220:8: error: invalid template-id
  220 |     -> sequence_range<typename boost::mpl::eval_if<
      |        ^~~~~~~~~~~~~~
/usr/include/zug/sequence.hpp:220:32: error: ‘boost’ has not been declared
  220 |     -> sequence_range<typename boost::mpl::eval_if<
      |                                ^~~~~
/usr/include/zug/sequence.hpp:220:51: error: expected ‘(’ before ‘<’ token
  220 |     -> sequence_range<typename boost::mpl::eval_if<
      |                                                   ^
      |                                                   (
/usr/include/zug/sequence.hpp:221:74: error: expected primary-expression before ‘,’ token
  221 |                           std::is_same<ValueT, detail::deduce_value_type>,
      |                                                                          ^
/usr/include/zug/sequence.hpp:223:50: error: expected initializer before ‘::’ token
  223 |                           meta::identity<ValueT>>::type,

The text was updated successfully, but these errors were encountered:

tusooa · 2021-01-23T00:44:56Z

With ZUG_VARIANT_BOOST (succeeds):

tlcr: 0 2021,1,22 (5) 19,40,04 tusooa@tusooa-yoga /home/test/
] cat zug-test.cpp

#include <vector>
#define ZUG_VARIANT_BOOST 1
#include <boost/mpl/eval_if.hpp>
#include <zug/sequence.hpp>

int main()
{
    std::vector<int> foo;
    auto seq = zug::sequence(zug::identity, foo);
    for (auto i: seq) {
    }
}
tlcr: 0 2021,1,22 (5) 19,40,34 tusooa@tusooa-yoga /home/test/
] g++ -std=gnu++17 zug-test.cpp

Without ZUG_VARIANT_BOOST:

] cat zug-test.cpp

#include <vector>
#include <boost/mpl/eval_if.hpp>
#include <zug/sequence.hpp>

int main()
{
    std::vector<int> foo;
    auto seq = zug::sequence(zug::identity, foo);
    for (auto i: seq) {
    }
}

In file included from /usr/include/zug/skip.hpp:25,
                 from /usr/include/zug/reductor.hpp:11,
                 from /usr/include/zug/sequence.hpp:15,
                 from zug-test.cpp:4:
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant: In instantiation of ‘constexpr const size_t std::variant_size_v<zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >’:
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1014:10:   required from ‘struct std::__detail::__variant::__gen_vtable<true, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_traits<zug::skip_state<SkippedT, CalledT> >::complete(T&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:23&&)>&&, zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&&>’
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1638:23:   required from ‘constexpr decltype(auto) std::__do_visit(_Visitor&&, _Variants&& ...) [with bool __use_index = false; bool __same_return_types = true; _Visitor = zug::state_traits<zug::skip_state<SkippedT, CalledT> >::complete(T&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:23&&)>; _Variants = {zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >}]’
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1654:24:   required from ‘constexpr decltype(auto) std::visit(_Visitor&&, _Variants&& ...) [with _Visitor = zug::state_traits<zug::skip_state<SkippedT, CalledT> >::complete(T&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:23&&)>; _Variants = {zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >}]’
/usr/include/zug/skip.hpp:76:25:   required from ‘static decltype(auto) zug::state_traits<zug::skip_state<SkippedT, CalledT> >::complete(T&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]’
/usr/include/zug/state_traits.hpp:103:39:   required from ‘decltype(auto) zug::state_complete(T&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >]’
/usr/include/zug/reductor.hpp:26:45:   required from ‘struct zug::reductor_base<zug::detail::caller<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)> >, zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >’
/usr/include/zug/reductor.hpp:179:8:   required from ‘struct zug::empty_reductor<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)>, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*>’
/usr/include/zug/sequence.hpp:126:20:   required from ‘struct zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::<unnamed>’
/usr/include/zug/sequence.hpp:127:7:   required from ‘struct zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >’
/usr/include/zug/sequence.hpp:184:16:   required from ‘struct zug::sequence_range<int, zug::identity_t, std::vector<int, std::allocator<int> > >::iterator’
zug-test.cpp:10:18:   required from here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:94:29: error: incomplete type ‘std::variant_size<zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >’ used in nested name specifier
   94 |     inline constexpr size_t variant_size_v = variant_size<_Variant>::value;
      |                             ^~~~~~~~~~~~~~
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant: In instantiation of ‘constexpr decltype(auto) std::__do_visit(_Visitor&&, _Variants&& ...) [with bool __use_index = false; bool __same_return_types = true; _Visitor = zug::state_traits<zug::skip_state<SkippedT, CalledT> >::complete(T&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:23&&)>; _Variants = {zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >}]’:
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1654:24:   required from ‘constexpr decltype(auto) std::visit(_Visitor&&, _Variants&& ...) [with _Visitor = zug::state_traits<zug::skip_state<SkippedT, CalledT> >::complete(T&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:23&&)>; _Variants = {zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >}]’
/usr/include/zug/skip.hpp:76:25:   required from ‘static decltype(auto) zug::state_traits<zug::skip_state<SkippedT, CalledT> >::complete(T&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]’
/usr/include/zug/state_traits.hpp:103:39:   required from ‘decltype(auto) zug::state_complete(T&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >]’
/usr/include/zug/reductor.hpp:26:45:   required from ‘struct zug::reductor_base<zug::detail::caller<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)> >, zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >’
/usr/include/zug/reductor.hpp:179:8:   required from ‘struct zug::empty_reductor<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)>, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*>’
/usr/include/zug/sequence.hpp:126:20:   required from ‘struct zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::<unnamed>’
/usr/include/zug/sequence.hpp:127:7:   required from ‘struct zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >’
/usr/include/zug/sequence.hpp:184:16:   required from ‘struct zug::sequence_range<int, zug::identity_t, std::vector<int, std::allocator<int> > >::iterator’
zug-test.cpp:10:18:   required from here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1638:23: error: ‘_S_vtable’ is not a member of ‘std::__detail::__variant::__gen_vtable<true, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_traits<zug::skip_state<SkippedT, CalledT> >::complete(T&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:23&&)>&&, zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&&>’
 1638 |       constexpr auto& __vtable = __detail::__variant::__gen_vtable<
      |                       ^~~~~~~~
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant: In instantiation of ‘constexpr decltype(auto) std::__do_visit(_Visitor&&, _Variants&& ...) [with bool __use_index = false; bool __same_return_types = true; _Visitor = zug::state_traits<zug::skip_state<SkippedT, CalledT> >::rewrap(T&&, U&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; U = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:25&&)>; _Variants = {zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >}]’:
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1654:24:   required from ‘constexpr decltype(auto) std::visit(_Visitor&&, _Variants&& ...) [with _Visitor = zug::state_traits<zug::skip_state<SkippedT, CalledT> >::rewrap(T&&, U&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; U = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:25&&)>; _Variants = {zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >}]’
/usr/include/zug/skip.hpp:92:25:   required from ‘static decltype(auto) zug::state_traits<zug::skip_state<SkippedT, CalledT> >::rewrap(T&&, U&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; U = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]’
/usr/include/zug/state_traits.hpp:148:37:   required from ‘decltype(auto) zug::state_rewrap(T&&, U&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; U = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*]’
/usr/include/zug/reductor.hpp:55:30:   required from ‘void zug::reductor_base<ReducingFnT, StateT, InputTs>::current(T&&) [with T = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; ReducingFnT = zug::detail::caller<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)> >; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}]’
/usr/include/zug/sequence.hpp:63:9:   required from ‘zug::detail::sequence_data<ValueT, XformT>::sequence_data(zug::detail::sequence_data<ValueT, XformT>&&) [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:176:36:   required from ‘zug::sequence_range<ValueT, XformT, RangeTs>::iterator::iterator(zug::sequence_range<ValueT, XformT, RangeTs>::data_t) [with ValueT = int; XformT = zug::identity_t; RangeTs = {std::vector<int, std::allocator<int> >}; zug::sequence_range<ValueT, XformT, RangeTs>::data_t = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >; decltype (zug::comp(zug::iter(zug::detail::make_iterator_range((declval<const RangeTs&>)())...), declval<XformT>())) = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:194:44:   required from ‘zug::sequence_range<ValueT, XformT, RangeTs>::iterator zug::sequence_range<ValueT, XformT, RangeTs>::begin() const [with ValueT = int; XformT = zug::identity_t; RangeTs = {std::vector<int, std::allocator<int> >}]’
zug-test.cpp:10:18:   required from here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1638:23: error: ‘_S_vtable’ is not a member of ‘std::__detail::__variant::__gen_vtable<true, zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >, zug::state_traits<zug::skip_state<SkippedT, CalledT> >::rewrap(T&&, U&&) [with T = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; U = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:25&&)>&&, zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&&>’
In file included from /usr/include/zug/sequence.hpp:15,
                 from zug-test.cpp:4:
/usr/include/zug/reductor.hpp: In instantiation of ‘void zug::reductor_base<ReducingFnT, StateT, InputTs>::current(T&&) [with T = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; ReducingFnT = zug::detail::caller<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)> >; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}]’:
/usr/include/zug/sequence.hpp:63:9:   required from ‘zug::detail::sequence_data<ValueT, XformT>::sequence_data(zug::detail::sequence_data<ValueT, XformT>&&) [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:176:36:   required from ‘zug::sequence_range<ValueT, XformT, RangeTs>::iterator::iterator(zug::sequence_range<ValueT, XformT, RangeTs>::data_t) [with ValueT = int; XformT = zug::identity_t; RangeTs = {std::vector<int, std::allocator<int> >}; zug::sequence_range<ValueT, XformT, RangeTs>::data_t = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >; decltype (zug::comp(zug::iter(zug::detail::make_iterator_range((declval<const RangeTs&>)())...), declval<XformT>())) = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:194:44:   required from ‘zug::sequence_range<ValueT, XformT, RangeTs>::iterator zug::sequence_range<ValueT, XformT, RangeTs>::begin() const [with ValueT = int; XformT = zug::identity_t; RangeTs = {std::vector<int, std::allocator<int> >}]’
zug-test.cpp:10:18:   required from here
/usr/include/zug/reductor.hpp:55:16: error: no match for ‘operator=’ (operand types are ‘zug::reductor_base<zug::detail::caller<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)> >, zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >::state_type’ {aka ‘zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >’} and ‘void’)
   55 |         state_ = state_rewrap(std::move(state_), std::forward<T>(x));
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/zug/reductor.hpp:11,
                 from /usr/include/zug/sequence.hpp:15,
                 from zug-test.cpp:4:
/usr/include/zug/skip.hpp:46:8: note: candidate: ‘zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >& zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >::operator=(const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&)’
   46 | struct skip_state : ZUG_VARIANT<SkippedT, CalledT>
      |        ^~~~~~~~~~
/usr/include/zug/skip.hpp:46:8: note:   no known conversion for argument 1 from ‘void’ to ‘const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&’
/usr/include/zug/skip.hpp:46:8: note: candidate: ‘zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >& zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >::operator=(zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&&)’
/usr/include/zug/skip.hpp:46:8: note:   no known conversion for argument 1 from ‘void’ to ‘zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&&’
In file included from /usr/include/zug/skip.hpp:25,
                 from /usr/include/zug/reductor.hpp:11,
                 from /usr/include/zug/sequence.hpp:15,
                 from zug-test.cpp:4:
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant: In instantiation of ‘struct std::variant_size<const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >’:
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:94:29:   required from ‘constexpr const size_t std::variant_size_v<const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >’
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1014:10:   required from ‘struct std::__detail::__variant::__gen_vtable<true, bool, zug::state_traits<zug::skip_state<SkippedT, CalledT> >::is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:22&&)>&&, const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&>’
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1638:23:   required from ‘constexpr decltype(auto) std::__do_visit(_Visitor&&, _Variants&& ...) [with bool __use_index = false; bool __same_return_types = true; _Visitor = zug::state_traits<zug::skip_state<SkippedT, CalledT> >::is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:22&&)>; _Variants = {const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&}]’
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1654:24:   required from ‘constexpr decltype(auto) std::visit(_Visitor&&, _Variants&& ...) [with _Visitor = zug::state_traits<zug::skip_state<SkippedT, CalledT> >::is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:22&&)>; _Variants = {const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&}]’
/usr/include/zug/skip.hpp:69:25:   required from ‘static decltype(auto) zug::state_traits<zug::skip_state<SkippedT, CalledT> >::is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]’
/usr/include/zug/state_traits.hpp:112:41:   required from ‘bool zug::state_is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&]’
/usr/include/zug/reductor.hpp:33:62:   required from ‘zug::reductor_base<ReducingFnT, StateT, InputTs>::operator bool() const [with ReducingFnT = zug::detail::caller<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)> >; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}]’
/usr/include/zug/sequence.hpp:116:40:   required from ‘void zug::detail::sequence_data<ValueT, XformT>::pull() [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:53:9:   required from ‘zug::detail::sequence_data<ValueT, XformT>::sequence_data(const XformT&) [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:194:44:   required from ‘zug::sequence_range<ValueT, XformT, RangeTs>::iterator zug::sequence_range<ValueT, XformT, RangeTs>::begin() const [with ValueT = int; XformT = zug::identity_t; RangeTs = {std::vector<int, std::allocator<int> >}]’
zug-test.cpp:10:18:   required from here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:81:12: error: invalid use of incomplete type ‘struct std::variant_size<zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >’
   81 |     struct variant_size<const _Variant> : variant_size<_Variant> {};
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:78:12: note: declaration of ‘struct std::variant_size<zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >’
   78 |     struct variant_size;
      |            ^~~~~~~~~~~~
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant: In instantiation of ‘constexpr const size_t std::variant_size_v<const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >’:
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1014:10:   required from ‘struct std::__detail::__variant::__gen_vtable<true, bool, zug::state_traits<zug::skip_state<SkippedT, CalledT> >::is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:22&&)>&&, const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&>’
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1638:23:   required from ‘constexpr decltype(auto) std::__do_visit(_Visitor&&, _Variants&& ...) [with bool __use_index = false; bool __same_return_types = true; _Visitor = zug::state_traits<zug::skip_state<SkippedT, CalledT> >::is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:22&&)>; _Variants = {const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&}]’
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1654:24:   required from ‘constexpr decltype(auto) std::visit(_Visitor&&, _Variants&& ...) [with _Visitor = zug::state_traits<zug::skip_state<SkippedT, CalledT> >::is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:22&&)>; _Variants = {const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&}]’
/usr/include/zug/skip.hpp:69:25:   required from ‘static decltype(auto) zug::state_traits<zug::skip_state<SkippedT, CalledT> >::is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]’
/usr/include/zug/state_traits.hpp:112:41:   required from ‘bool zug::state_is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&]’
/usr/include/zug/reductor.hpp:33:62:   required from ‘zug::reductor_base<ReducingFnT, StateT, InputTs>::operator bool() const [with ReducingFnT = zug::detail::caller<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)> >; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}]’
/usr/include/zug/sequence.hpp:116:40:   required from ‘void zug::detail::sequence_data<ValueT, XformT>::pull() [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:53:9:   required from ‘zug::detail::sequence_data<ValueT, XformT>::sequence_data(const XformT&) [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:194:44:   required from ‘zug::sequence_range<ValueT, XformT, RangeTs>::iterator zug::sequence_range<ValueT, XformT, RangeTs>::begin() const [with ValueT = int; XformT = zug::identity_t; RangeTs = {std::vector<int, std::allocator<int> >}]’
zug-test.cpp:10:18:   required from here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:94:29: error: ‘value’ is not a member of ‘std::variant_size<const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >’
   94 |     inline constexpr size_t variant_size_v = variant_size<_Variant>::value;
      |                             ^~~~~~~~~~~~~~
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant: In instantiation of ‘constexpr decltype(auto) std::__do_visit(_Visitor&&, _Variants&& ...) [with bool __use_index = false; bool __same_return_types = true; _Visitor = zug::state_traits<zug::skip_state<SkippedT, CalledT> >::is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:22&&)>; _Variants = {const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&}]’:
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1654:24:   required from ‘constexpr decltype(auto) std::visit(_Visitor&&, _Variants&& ...) [with _Visitor = zug::state_traits<zug::skip_state<SkippedT, CalledT> >::is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:22&&)>; _Variants = {const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&}]’
/usr/include/zug/skip.hpp:69:25:   required from ‘static decltype(auto) zug::state_traits<zug::skip_state<SkippedT, CalledT> >::is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]’
/usr/include/zug/state_traits.hpp:112:41:   required from ‘bool zug::state_is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&]’
/usr/include/zug/reductor.hpp:33:62:   required from ‘zug::reductor_base<ReducingFnT, StateT, InputTs>::operator bool() const [with ReducingFnT = zug::detail::caller<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)> >; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}]’
/usr/include/zug/sequence.hpp:116:40:   required from ‘void zug::detail::sequence_data<ValueT, XformT>::pull() [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:53:9:   required from ‘zug::detail::sequence_data<ValueT, XformT>::sequence_data(const XformT&) [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:194:44:   required from ‘zug::sequence_range<ValueT, XformT, RangeTs>::iterator zug::sequence_range<ValueT, XformT, RangeTs>::begin() const [with ValueT = int; XformT = zug::identity_t; RangeTs = {std::vector<int, std::allocator<int> >}]’
zug-test.cpp:10:18:   required from here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1638:23: error: ‘_S_vtable’ is not a member of ‘std::__detail::__variant::__gen_vtable<true, bool, zug::state_traits<zug::skip_state<SkippedT, CalledT> >::is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&; SkippedT = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*; CalledT = zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > >]::<lambda(auto:22&&)>&&, const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&>’
 1638 |       constexpr auto& __vtable = __detail::__variant::__gen_vtable<
      |                       ^~~~~~~~
In file included from /usr/include/zug/detail/reduce_nested_non_empty_nullary.hpp:11,
                 from /usr/include/zug/detail/reduce_nested_non_empty.hpp:13,
                 from /usr/include/zug/reduce.hpp:12,
                 from /usr/include/zug/transduce.hpp:11,
                 from /usr/include/zug/into.hpp:13,
                 from /usr/include/zug/meta.hpp:11,
                 from /usr/include/zug/sequence.hpp:13,
                 from zug-test.cpp:4:
/usr/include/zug/state_traits.hpp: In instantiation of ‘bool zug::state_is_reduced(T&&) [with T = const zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&]’:
/usr/include/zug/reductor.hpp:33:62:   required from ‘zug::reductor_base<ReducingFnT, StateT, InputTs>::operator bool() const [with ReducingFnT = zug::detail::caller<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)> >; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}]’
/usr/include/zug/sequence.hpp:116:40:   required from ‘void zug::detail::sequence_data<ValueT, XformT>::pull() [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:53:9:   required from ‘zug::detail::sequence_data<ValueT, XformT>::sequence_data(const XformT&) [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:194:44:   required from ‘zug::sequence_range<ValueT, XformT, RangeTs>::iterator zug::sequence_range<ValueT, XformT, RangeTs>::begin() const [with ValueT = int; XformT = zug::identity_t; RangeTs = {std::vector<int, std::allocator<int> >}]’
zug-test.cpp:10:18:   required from here
/usr/include/zug/state_traits.hpp:112:41: error: void value not ignored as it ought to be
  112 |     return state_traits_t<T>::is_reduced(std::forward<T>(s));
      |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/zug/skip.hpp:25,
                 from /usr/include/zug/reductor.hpp:11,
                 from /usr/include/zug/sequence.hpp:15,
                 from zug-test.cpp:4:
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant: In instantiation of ‘constexpr decltype(auto) std::__do_visit(_Visitor&&, _Variants&& ...) [with bool __use_index = false; bool __same_return_types = true; _Visitor = zug::call(ReducingFnT&&, StateT&&, InputTs&& ...) [with ReducingFnT = zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)>&; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}; std::enable_if_t<zug::is_skip_state<typename std::decay<Rhs>::type>{}, typename std::decay<Rhs>::type> = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >]::<lambda(auto:26&&)>; _Variants = {zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >}]’:
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1654:24:   required from ‘constexpr decltype(auto) std::visit(_Visitor&&, _Variants&& ...) [with _Visitor = zug::call(ReducingFnT&&, StateT&&, InputTs&& ...) [with ReducingFnT = zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)>&; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}; std::enable_if_t<zug::is_skip_state<typename std::decay<Rhs>::type>{}, typename std::decay<Rhs>::type> = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >]::<lambda(auto:26&&)>; _Variants = {zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >}]’
/usr/include/zug/skip.hpp:210:21:   required from ‘std::enable_if_t<zug::is_skip_state<typename std::decay<Rhs>::type>{}, typename std::decay<Rhs>::type> zug::call(ReducingFnT&&, StateT&&, InputTs&& ...) [with ReducingFnT = zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)>&; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}; std::enable_if_t<zug::is_skip_state<typename std::decay<Rhs>::type>{}, typename std::decay<Rhs>::type> = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >]’
/usr/include/zug/reductor.hpp:165:20:   required from ‘decltype(auto) zug::detail::caller<ReducingFnT>::operator()(Args&& ...) [with Args = {zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >}; ReducingFnT = zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)>]’
/usr/include/zug/reductor.hpp:70:14:   required from ‘zug::reductor_base<ReducingFnT, StateT, InputTs>& zug::reductor_base<ReducingFnT, StateT, InputTs>::operator()(InputTs2&& ...) & [with InputTs2 = {}; ReducingFnT = zug::detail::caller<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)> >; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}]’
/usr/include/zug/sequence.hpp:117:17:   required from ‘void zug::detail::sequence_data<ValueT, XformT>::pull() [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:53:9:   required from ‘zug::detail::sequence_data<ValueT, XformT>::sequence_data(const XformT&) [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:194:44:   required from ‘zug::sequence_range<ValueT, XformT, RangeTs>::iterator zug::sequence_range<ValueT, XformT, RangeTs>::begin() const [with ValueT = int; XformT = zug::identity_t; RangeTs = {std::vector<int, std::allocator<int> >}]’
zug-test.cpp:10:18:   required from here
/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9/variant:1638:23: error: ‘_S_vtable’ is not a member of ‘std::__detail::__variant::__gen_vtable<true, zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >, zug::call(ReducingFnT&&, StateT&&, InputTs&& ...) [with ReducingFnT = zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)>&; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}; std::enable_if_t<zug::is_skip_state<typename std::decay<Rhs>::type>{}, typename std::decay<Rhs>::type> = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >]::<lambda(auto:26&&)>&&, zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >&&>’
 1638 |       constexpr auto& __vtable = __detail::__variant::__gen_vtable<
      |                       ^~~~~~~~
In file included from /usr/include/zug/reductor.hpp:11,
                 from /usr/include/zug/sequence.hpp:15,
                 from zug-test.cpp:4:
/usr/include/zug/skip.hpp: In instantiation of ‘std::enable_if_t<zug::is_skip_state<typename std::decay<Rhs>::type>{}, typename std::decay<Rhs>::type> zug::call(ReducingFnT&&, StateT&&, InputTs&& ...) [with ReducingFnT = zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)>&; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}; std::enable_if_t<zug::is_skip_state<typename std::decay<Rhs>::type>{}, typename std::decay<Rhs>::type> = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >]’:
/usr/include/zug/reductor.hpp:165:20:   required from ‘decltype(auto) zug::detail::caller<ReducingFnT>::operator()(Args&& ...) [with Args = {zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >}; ReducingFnT = zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)>]’
/usr/include/zug/reductor.hpp:70:14:   required from ‘zug::reductor_base<ReducingFnT, StateT, InputTs>& zug::reductor_base<ReducingFnT, StateT, InputTs>::operator()(InputTs2&& ...) & [with InputTs2 = {}; ReducingFnT = zug::detail::caller<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)> >; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}]’
/usr/include/zug/sequence.hpp:117:17:   required from ‘void zug::detail::sequence_data<ValueT, XformT>::pull() [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:53:9:   required from ‘zug::detail::sequence_data<ValueT, XformT>::sequence_data(const XformT&) [with ValueT = int; XformT = zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t>]’
/usr/include/zug/sequence.hpp:194:44:   required from ‘zug::sequence_range<ValueT, XformT, RangeTs>::iterator zug::sequence_range<ValueT, XformT, RangeTs>::begin() const [with ValueT = int; XformT = zug::identity_t; RangeTs = {std::vector<int, std::allocator<int> >}]’
zug-test.cpp:10:18:   required from here
/usr/include/zug/skip.hpp:210:21: error: could not convert ‘std::visit<zug::call(ReducingFnT&&, StateT&&, InputTs&& ...) [with ReducingFnT = zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)>&; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}; std::enable_if_t<zug::is_skip_state<typename std::decay<Rhs>::type>{}, typename std::decay<Rhs>::type> = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >]::<lambda(auto:26&&)>, zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >(<lambda closure object>zug::call(ReducingFnT&&, StateT&&, InputTs&& ...) [with ReducingFnT = zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)> [with auto:27 = zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >::step_t]::<lambda(auto:28&&, auto:29&& ...)>&; StateT = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >; InputTs = {}; std::enable_if_t<zug::is_skip_state<typename std::decay<Rhs>::type>{}, typename std::decay<Rhs>::type> = zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >]::<lambda(auto:26&&)>{(* & step)}, (* & std::forward<zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >((* & state))))’ from ‘void’ to ‘std::enable_if_t<true, zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > > >’ {aka ‘zug::skip_state<zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, zug::state_wrapper<zug::iter_tag, zug::detail::sequence_data<int, zug::composed<zug::iter(InputRangeT&&) [with InputRangeT = zug::detail::iterator_range<__gnu_cxx::__normal_iterator<const int*, std::vector<int> >, __gnu_cxx::__normal_iterator<const int*, std::vector<int> > >]::<lambda(auto:27&&)>, zug::identity_t> >*, std::tuple<__gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<const int*, std::vector<int, std::allocator<int> > > > > >’}
  210 |     return ZUG_VISIT(
      |                     ^
      |                     |
      |                     void

Without boost/mpl include:

tlcr: 1 2021,1,22 (5) 19,44,21 tusooa@tusooa-yoga /home/test/
] cat zug-test.cpp

#include <vector>
#include <zug/sequence.hpp>

int main()
{
    std::vector<int> foo;
    auto seq = zug::sequence(zug::identity, foo);
    for (auto i: seq) {
    }
}
tlcr: 0 2021,1,22 (5) 19,44,26 tusooa@tusooa-yoga /home/test/
] g++ -std=gnu++17 zug-test.cpp
In file included from zug-test.cpp:3:
/usr/include/zug/sequence.hpp:225:47: error: wrong number of template arguments (1, should be at least 2)
  225 |                       std::decay_t<RangeTs>...>
      |                                               ^
/usr/include/zug/sequence.hpp:158:8: note: provided for ‘template<class ValueT, class XformT, class ... RangeTs> struct zug::sequence_range’
  158 | struct sequence_range
      |        ^~~~~~~~~~~~~~
/usr/include/zug/sequence.hpp:225:47: error: wrong number of template arguments (1, should be at least 2)
  225 |                       std::decay_t<RangeTs>...>
      |                                               ^
/usr/include/zug/sequence.hpp:158:8: note: provided for ‘template<class ValueT, class XformT, class ... RangeTs> struct zug::sequence_range’
  158 | struct sequence_range
      |        ^~~~~~~~~~~~~~
/usr/include/zug/sequence.hpp:225:47: error: wrong number of template arguments (1, should be at least 2)
  225 |                       std::decay_t<RangeTs>...>
      |                                               ^
/usr/include/zug/sequence.hpp:158:8: note: provided for ‘template<class ValueT, class XformT, class ... RangeTs> struct zug::sequence_range’
  158 | struct sequence_range
      |        ^~~~~~~~~~~~~~
/usr/include/zug/sequence.hpp:225:47: error: wrong number of template arguments (1, should be at least 2)
  225 |                       std::decay_t<RangeTs>...>
      |                                               ^
/usr/include/zug/sequence.hpp:158:8: note: provided for ‘template<class ValueT, class XformT, class ... RangeTs> struct zug::sequence_range’
  158 | struct sequence_range
      |        ^~~~~~~~~~~~~~
/usr/include/zug/sequence.hpp:220:8: error: invalid template-id
  220 |     -> sequence_range<typename boost::mpl::eval_if<
      |        ^~~~~~~~~~~~~~
/usr/include/zug/sequence.hpp:220:32: error: ‘boost’ has not been declared
  220 |     -> sequence_range<typename boost::mpl::eval_if<
      |                                ^~~~~
/usr/include/zug/sequence.hpp:220:51: error: expected ‘(’ before ‘<’ token
  220 |     -> sequence_range<typename boost::mpl::eval_if<
      |                                                   ^
      |                                                   (
/usr/include/zug/sequence.hpp:221:74: error: expected primary-expression before ‘,’ token
  221 |                           std::is_same<ValueT, detail::deduce_value_type>,
      |                                                                          ^
/usr/include/zug/sequence.hpp:223:50: error: expected initializer before ‘::’ token
  223 |                           meta::identity<ValueT>>::type,
      |                                                  ^~
zug-test.cpp: In function ‘int main()’:
zug-test.cpp:8:21: error: ‘sequence’ is not a member of ‘zug’
    8 |     auto seq = zug::sequence(zug::identity, foo);
      |                     ^~~~~~~~

Yohsi · 2021-04-22T21:06:43Z

This seems to be an issue with gcc (or even with the C++ standard?) that doesn't allow std::visit to be applied on a class inherited from std::variant.
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90943 and https://stackoverflow.com/questions/51309467/using-stdvisit-on-a-class-inheriting-from-stdvariant-libstdc-vs-libc

zug can't be built with std::variant for now. See: arximboldi/zug#24

tusooa changed the title ~~sequence depends on boost::mpl but without including it~~ Build failure when using std::variant Jan 23, 2021

arximboldi added the bug Something isn't working label Jan 17, 2022

jacktony980 pushed a commit to jacktony980/sendingcpp that referenced this issue May 15, 2023

Fix build failure

dcb098b

zug can't be built with std::variant for now. See: arximboldi/zug#24

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Build failure when using std::variant #24

Build failure when using std::variant #24

tusooa commented Jan 23, 2021

tusooa commented Jan 23, 2021 •

edited

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Yohsi commented Apr 22, 2021

Build failure when using std::variant #24

Build failure when using std::variant #24

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tusooa commented Jan 23, 2021

tusooa commented Jan 23, 2021 • edited Loading

Yohsi commented Apr 22, 2021

tusooa commented Jan 23, 2021 •

edited

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