Compilation error when using logger, process_queue and member function action

Expected Behavior

Compilation succeeds

Actual Behavior

Compilation fails with error C2672: '`anonymous-namespace'::logger::log_action': no matching overloaded function found because of error C2039: 'get': is not a member of 'boost::ext::sml::v1_1_9::aux::zero_wrapper<T,void>'

Steps to Reproduce the Problem

Sample code:

#include <queue>

#include "boost/sml.hpp"

namespace sml = boost::sml;

namespace {
struct s1
{};

struct bug
{
   bug() {}

   auto operator()()
   {
      using namespace sml;
      return make_transition_table(*state<s1> + event<initial> / &bug::action);
   }

   void action() {}
};

struct logger
{
   template<class SM, class TEvent>
   void log_process_event(const TEvent &)
   {}

   template<class SM, class TAction, class TEvent>
   void log_action(const TAction &, const TEvent &)
   {}
};

void test()
{
   logger log;
   sml::sm<bug, sml::logger<logger>, sml::process_queue<std::queue>> sm {log};
}

} // namespace

Removing sml::process_queue policy makes compilation succeed. Curiously, the no-argument constructor must be provided for compilation to succeed (= default will not do).

Specifications

• Version: v1.1.9
• Platform: Windows x64
• Compiler: MSVC 14.37.32822

-       return make_transition_table(*state<s1> + event<initial> / &bug::action);
+       return make_transition_table(*state<s1> + event<initial> / wrap(&bug::action));

does the trick with SML 1.1.4 (gcc 9.4, invoked with gcc --std=c++2a)