模板类中没有匹配的函数

Question

当我尝试在我的mingw32编译器上编译此代码时,我没有得到匹配的成员函数错误

#include <iostream> 
using std::cout;
template <class T>
class Pattern
{
public:
    Pattern(): element(){

        cout<< "default c-tor";
        }

    Pattern(Pattern &copy): element(copy.element){

        cout<< "copy c-tor";

        }

    Pattern& operator=(Pattern &assgn)
    {
        cout<<" assignment operator";
       element = assgn.element;
       return *this;
    }

    ~Pattern(){

        cout<<"destructor";

        }

private:
     T element;
};

template <class T>
Pattern<T> creator()
{
   cout<< "Testing creator";
   Pattern<T> pat;
   return pat;
}

int main()
{
   Pattern<double> pt1(creator<double>());
   Pattern<double> pt2 = creator<double>();
}

有人请告诉我如何解决问题.