traits问题

#include <iostream>  
#include <typeinfo>
#include <iterator>

using namespace std;  
 
class A
{
    public:
        A(int i=10)
        {
            k=i;   
        }
        int k;
};

template<class it>
void fun(it)
{
     typename iterator_traits<it>::reference reference;//编译时这行总是提示  [Error] 'reference' declared as reference but not initialized
        cout<<typeid(reference).name()<<endl;
}
int main( )   
{  
   
   A *a=new A(6);
   fun(a);
}