Wrong Action is instantiated and called for initial event

[stirwl]

Compiler report an undefined reference error. It was seeking Action1 for initial event and State1.

undefined reference to `void Action1::operator()<boost::ext::sml::v1_1_6::back::initial>(boost::ext::sml::v1_1_6::back::initial const&, State1&) const'

But idle state has no on_entry defined.
Even we want one, shouldn't the default be
void SomeAction::operator()<boost::ext::sml::v1_1_6::back::initial>(boost::ext::sml::v1_1_6::back::initial const&, StateIdle&) const
?

sm.h:

#pragma once
#include <boost/sml.hpp>

namespace sml = boost::sml;


struct next {};

struct State1{int i;
};

struct Action1{
  void operator()(const auto &evt, State1 & s)const;
};

struct hello_world {
  auto operator()() const {
    using namespace sml;
    return make_transition_table(
      *"idle"_s + event<next>  = state<State1>,
       state<State1> + sml::on_entry<_> /Action1(),
       state<State1> + event<next>  = X
    );
  }
};

sm.cpp:

#include "sm.h"

void Action1::operator()(const auto &evt, State1 &s) const
{
}

main.cpp:

#include "sm.h"
//#include "sm.cpp" //will be fine with this line
int main()
{
  using namespace sml;

  sm<hello_world> sm;
}

sm.zip

Error msg:

$ g++ -std=c++20 main.cpp sm.cpp
D:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/12.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe:
 D:\msys64\tmp\ccqXGsRK.o:main.cpp:(.text$_ZN5boost3ext3sml6v1_1_65front4callINS2_4back8on_entryINS5
_1_ENS5_7initialEEENS2_3aux9type_listIJRKS8_R6State1EEENS5_9no_policyEE7executeINSA_12zero_wrapperI7
Action1vEENS5_7sm_implINS5_9sm_policyI11hello_worldJEEEEENSA_4poolIJSF_EEENSS_IJSR_EEEEEDaT_RKS9_RT0
_RT1_RT2_[_ZN5boost3ext3sml6v1_1_65front4callINS2_4back8on_entryINS5_1_ENS5_7initialEEENS2_3aux9type
_listIJRKS8_R6State1EEENS5_9no_policyEE7executeINSA_12zero_wrapperI7Action1vEENS5_7sm_implINS5_9sm_p
olicyI11hello_worldJEEEEENSA_4poolIJSF_EEENSS_IJSR_EEEEEDaT_RKS9_RT0_RT1_RT2_]+0x61): undefined refe
rence to `void Action1::operator()<boost::ext::sml::v1_1_6::back::initial>(boost::ext::sml::v1_1_6::
back::initial const&, State1&) const'
collect2.exe: error: ld returned 1 exit status