[Boost-users] Problem compiling a statemachine with "class" instead of "struct"

Hi folks, we have run into an interesting problem when compiling one of our state machines using the boost state chart templates. If we instantiate a state like this: struct Active : public boost::statechart::simple_state< Active, PRX5StateMachine > { public: Active() : m_data("") {} ~Active() {} std::string & Data() { return m_data;} const std::string& Data() const { return m_data; } private: std::string m_data; }; and use it in our code, everything compiles fine. As soon as we change the declaration to class Active : public boost::statechart::simple_state< Active, PRX5StateMachine > we get massive compiler errors, which look like this: /usr/include/boost/statechart/simple_state.hpp:832: error: within this context /usr/include/boost/statechart/state_machine.hpp:243: error: ‘typedef struct boost::statechart::detail::rtti_policy boost::statechart::state_machine::rtti_policy_type’ is inaccessible Is it mandatory to inherit from simple_state via a struct and not from a class? Thanks for any inputs on this. On request I post two source directories which show the problem. Cheers, Rudi