boost/1.85.0: include boost/msm/front/state.hpp will cause build error

[auzn88]

Though unnecessary, but if we include boost/msm/front/states.hpp before include boost/msm/front/state_machine_def.hpp, it will cause compilation error. Using the following tutorial program as example:

CompositeTutorial.cpp

If we add #include <boost/msm/front/states.hpp> right after #include <iostream>, like this:

#include <iostream>

#include <boost/msm/front/states.hpp>  // <-- add this header here 
// back-end
#include <boost/msm/back11/state_machine.hpp>
//front-end
#include <boost/msm/front/state_machine_def.hpp>
...

then compiling it will give the following compilation error:

In file included from CompositeTutorial.cpp:12:
./boost/msm/front/states.hpp:57:46: error: ‘insert_range’ in namespace ‘boost::fusion::result_of’ does not name a template type
   57 |         typename ::boost::fusion::result_of::insert_range<
      |                                              ^~~~~~~~~~~~
./boost/msm/front/states.hpp:57:58: error: expected template-argument before ‘<’ token
   57 |         typename ::boost::fusion::result_of::insert_range<
      |                                                          ^
./boost/msm/front/states.hpp:57:58: error: expected ‘>’ before ‘<’ token
./boost/msm/front/states.hpp:62:5: error: template argument 1 is invalid
   62 |     >::type type;
      |     ^
./boost/msm/front/states.hpp:62:6: error: ‘<declaration error>’ is not a template [-fpermissive]
   62 |     >::type type;
      |      ^~

tested using gcc9 & gcc13. Only 1.85 has this issue