Getting the implicitly deleted error when using a struct-CodePudding

I'm getting this error:

<source>:48:32: error: use of deleted function 'FPTask_sim::Data_T::Data_T()'
   48 | FPTask_sim::Data_T FPTask_sim::_data;
      |                                ^~~~~
<source>:40:9: note: 'FPTask_sim::Data_T::Data_T()' is implicitly deleted because the default definition would be ill-formed:
   40 |       } Data_T;
      |         ^~~~~~

You can recreate the error using stripped version of my code:

(NOTE: comment the "#define BREAK_EVERYTHING" and the code will compile)

#define BREAK_EVERYTHING

namespace tinyfsm
{
    struct Event {};
}


namespace EventConsts
{
    struct EventCode_T  {};
    struct Event_T      {};

   struct EventStruct_T : tinyfsm::Event
    {
    #ifdef BREAK_EVERYTHING
        EventStruct_T(const Event_T& Event);           
    #else
        struct Event { };
    #endif
    };
}


class FPTask_sim
{
   public:
        FPTask_sim();
         
      typedef struct
      {
         tinyfsm::Event ARG_react_01_unused_arg01;

         EventConsts::EventStruct_T ARG_react_02_unused_arg01;          // These lines seem to be causing the issue
         EventConsts::EventStruct_T ARG_dispatch_e;                     // These lines seem to be causing the issue
      } Data_T;

      static Data_T _data;
      static Data_T _call_data;
};



FPTask_sim::Data_T FPTask_sim::_data;

int main()
{
    bool exampleVariable;
}

I'm thinking this is being caused by the

EventStruct_T(const Event_T& Event);

line, specifically because its being passed by reference and the overall object "_data" is static. Not sure how to fix this though.

Thanks!

EDITS:

Sorry, forgot to include the constructor that is in it already. It looks like it just copies the Event_T obj to EventStruct_T. If Im understanding what you are saying, I need to either give values when declaring the object or add in the blank default constructor. Right?

#define BREAK_EVERYTHING

namespace tinyfsm
{
    struct Event {};
}

namespace EventConsts
{
    struct Event_T      {bool a;};                

   struct EventStruct_T : tinyfsm::Event
    {
        bool a;
    #ifdef BREAK_EVERYTHING
        //EventStruct_T(){}                            // New default constructor? 
        EventStruct_T() = default;                     // Answer provided by user17732522
        EventStruct_T(const Event_T& Event);           
    #else
        struct Event { };
    #endif
    };
}


class FPTask_sim
{
   public:
        FPTask_sim();
         
      typedef struct
      {
         tinyfsm::Event ARG_react_01_unused_arg01;

         EventConsts::EventStruct_T ARG_react_02_unused_arg01;          // These lines seem to be causing the issue
         EventConsts::EventStruct_T ARG_dispatch_e;                     // These lines seem to be causing the issue
      } Data_T;

      static Data_T _data;
      static Data_T _call_data;
};



FPTask_sim::Data_T FPTask_sim::_data;

int main()
{
    bool exampleVariable;
}

// Current constructor in separate file
EventConsts::EventStruct_T::EventStruct_T(const EventConsts::Event_T& Event) :        
      a(Event.a),
{}

CodePudding user response：

If you declare any constructor for a class, then the default constructor (constructor not requiring any argument) will not be declared implicitly.

So then there is no constructor to construct e.g. FPTask_sim::_data.ARG_react_02_unused_arg01 when you are trying to initialize it without constructor argument in FPTask_sim::Data_T FPTask_sim::_data;.

Either provide arguments to the initializer of FPTask_sim::_data so that FPTask_sim::_data.ARG_react_02_unused_arg01 and the other are given arguments from which they can be constructed, give them default-initializers in the definition of EventStruct_T or define a default constructor for EventStruct_T yourself.