compile error with boost fusion

[zhuoqiang]

• compiler: g++ 11 std=20
• boost 1.77
• visit_struct: 8c91d22

source code trigger the error

#include <visit_struct/visit_struct_boost_fusion.hpp>
BOOST_FUSION_DEFINE_STRUCT((), FusionParams,
                           (int, param1)(double, param2))

template <class Params>
constexpr void PopulateVsFoo(const Params& params) {
  visit_struct::for_each(params, []<typename T>(const char*, const T&) {});
}

void test() {
  FusionParams p;
  PopulateVsFoo(p);
}

compile error:

In file included from /param_test.cpp:1:
/visit_struct/include/visit_struct/visit_struct_boost_fusion.hpp: In instantiation of 'static void visit_struct::traits::visitable<S, typename std::enable_if<std::is_same<typename boost::mpl::sequence_tag<Sequence>::type, boost::fusion::fusion_sequence_tag>::value>::type>::apply(V&&, T&&) [with V = PopulateVsFoo<{anonymous}::FusionParams>(const {anonymous}::FusionParams&)::<lambda(const char*, const T&)>; T = const {anonymous}::FusionParams&; S = {anonymous}::FusionParams]':
/visit_struct/include/visit_struct/visit_struct.hpp:144:47:   required from 'constexpr typename std::enable_if<visit_struct::traits::is_visitable<typename visit_struct::traits::clean<S>::type>::value>::type visit_struct::for_each(S&&, V&&) [with V = PopulateVsFoo<{anonymous}::FusionParams>(const {anonymous}::FusionParams&)::<lambda(const char*, const T&)>; S = const {anonymous}::FusionParams&; typename std::enable_if<visit_struct::traits::is_visitable<typename visit_struct::traits::clean<S>::type>::value>::type = void; typename visit_struct::traits::clean<S>::type = {anonymous}::FusionParams]'
/param_test.cpp:6:25:   required from 'constexpr void PopulateVsFoo(const Params&) [with Params = {anonymous}::FusionParams]'
/param_test.cpp:11:16:   required from here
/visit_struct/include/visit_struct/visit_struct_boost_fusion.hpp:133:21: error: use of deleted function 'visit_struct::traits::visitable<{anonymous}::FusionParams, void>::fusion_visitor<PopulateVsFoo<{anonymous}::FusionParams>(const {anonymous}::FusionParams&)::<lambda(const char*, const T&)>&&, const {anonymous}::FusionParams&>::fusion_visitor(const visit_struct::traits::visitable<{anonymous}::FusionParams, void>::fusion_visitor<PopulateVsFoo<{anonymous}::FusionParams>(const {anonymous}::FusionParams&)::<lambda(const char*, const T&)>&&, const {anonymous}::FusionParams&>&)'
  133 |     fusion::for_each(Indices(), fv);
      |     ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
/visit_struct/include/visit_struct/visit_struct_boost_fusion.hpp:66:10: note: 'visit_struct::traits::visitable<{anonymous}::FusionParams, void>::fusion_visitor<PopulateVsFoo<{anonymous}::FusionParams>(const {anonymous}::FusionParams&)::<lambda(const char*, const T&)>&&, const {anonymous}::FusionParams&>::fusion_visitor(const visit_struct::traits::visitable<{anonymous}::FusionParams, void>::fusion_visitor<PopulateVsFoo<{anonymous}::FusionParams>(const {anonymous}::FusionParams&)::<lambda(const char*, const T&)>&&, const {anonymous}::FusionParams&>&)' is implicitly deleted because the default definition would be ill-formed:
   66 |   struct fusion_visitor {
      |          ^~~~~~~~~~~~~~
/visit_struct/include/visit_struct/visit_struct_boost_fusion.hpp:66:10: error: copying non-static data member 'PopulateVsFoo<{anonymous}::FusionParams>(const {anonymous}::FusionParams&)::<lambda(const char*, const T&)>&& visit_struct::traits::visitable<{anonymous}::FusionParams, void>::fusion_visitor<PopulateVsFoo<{anonymous}::FusionParams>(const {anonymous}::FusionParams&)::<lambda(const char*, const T&)>&&, const {anonymous}::FusionParams&>::visitor' of rvalue reference type
In file included from /boost/fusion/include/for_each.hpp:11,
                 from /visit_struct/include/visit_struct/visit_struct_boost_fusion.hpp:12,
                 from /param_test.cpp:1:
/boost/fusion/algorithm/iteration/for_each.hpp:41:37: note:   initializing argument 2 of 'constexpr typename boost::enable_if<boost::fusion::traits::is_sequence<Sequence> >::type boost::fusion::for_each(const Sequence&, F) [with Sequence = boost::mpl::range_c<unsigned int, 0, 2>; F = visit_struct::traits::visitable<{anonymous}::FusionParams, void>::fusion_visitor<PopulateVsFoo<{anonymous}::FusionParams>(const {anonymous}::FusionParams&)::<lambda(const char*, const T&)>&&, const {anonymous}::FusionParams&>; typename boost::enable_if<boost::fusion::traits::is_sequence<Sequence> >::type = void]'
   41 |     for_each(Sequence const& seq, F f)
      |                                   ~~^

[cbeck88]

Thanks, i havent tested this with latest boost, ill take a look