Boost lock free queue asserts for trivial assignment and destructor

Question

When trying to insert an "Event" into boost lock free queue, I receive: error: static assertion failed: (boost::has_trivial_destructor::value) and static assertion failed: (boost::has_trivial_assign::value). I know the requirement of the container is : T must have a copy constructor T must have a trivial assignment operator T must have a trivial destructor I am not sure why my event class does not meet these requirements.

I've read this question/answer : /boost/lockfree/queue.hpp: error: static assertion failed: (boost::has_trivial_destructor<T>::value). I don't see why my class doesn't satisfy the requirements.

struct Event
{
    typedef uint8_t Event_Type;

    //event bitmask..
    enum : uint8_t
    {
        SS      = 1,
        TS      = 2
    };

    static constexpr uint8_t BOTH = SS | TS;

    Event():      _time {}
                  ,_data1 {}
                  ,_eventType {}
                  ,_data2 {}
    {}

    Event(const Event& event_)
    {
        _id                  = event_._id;
        _time                = event_._time;
        _data1                = event_.data1;
        _eventType           = event_._eventType;
        _data2                = event_.data2;
    }

    template<Event_Type type, typename... Args >
    void update(Args...args)
    {
        _eventType |= type;
        apply(std::forward<Args>(args)...);
    }

    void apply(int32_t d)
    {
        data1 = d;
    }

    void apply(bool b)
    {
        data2= b;
    }

    template<typename Event, typename... Args>
    void apply(Event event, Args... args)
    {
        apply(event);
        apply(args...);
    }

    std::string                _id;
    int64_t                    _time;
    int32_t                    _data1;
    Event_Type                 _eventType;
    bool                       _data2;
};

boost::lockfree::queue<Event, boost::lockfree::fixed_sized<false>> q;
Event e;
e._id="test";    
q.push(event);

/boost/1.57.0/include/boost/static_assert.hpp:78:41: error: static assertion failed: (boost::has_trivial_destructor::value) # define BOOST_STATIC_ASSERT( ... ) static_assert(VA_ARGS, #VA_ARGS)

boost/1.57.0/include/boost/static_assert.hpp:78:41: error: static assertion failed: (boost::has_trivial_assign::value) # define BOOST_STATIC_ASSERT( ... ) static_assert(VA_ARGS, #VA_ARGS)

Answer 1

Your Event class has a member of type std::string, which has a non-trivial assignment operator and a non-trivial destructor. Those stop the auto-generated assignment operator and destructor of Event itself from being trivial. (Remember, "trivial" doesn't just mean "defaulted". It also means that the default behavior doesn't have to do anything interesting. A trivial assignment is just copying bits; a trivial destructor is a no-op.)