c++ error: redeclaration of "XXX" may not have default arguments

模板函数的默认参数似乎必须在第一次声明的时候给出。

stackoverflow上的例子

#include 
#include 

class MyClass {
    public:
    std::wstring msg = L"hey";
    MyClass(){};
};

class MyClass2{
    public:
    template<class T> MyClass2(T* t, int i);
};
template<class T>
MyClass2::MyClass2(T* t,int i=0){ std::wcout << t->msg << std::endl; }

int main(int argc, char **argv)
{
    MyClass mc;
    MyClass2 mc2(&mc);
    return 0;
}

会报如下错误

error: redeclaration of 'MyClass2::MyClass2(T*, int)' may not have default arguments [-fpermissive]

相关条款

[C++14: 8.3.6/4]: For non-template functions, default arguments can be added in later 
declarations of a function in the same scope. [..]
[C++14: 8.3.6/6]: Except for member functions of class templates, the default 
arguments in a member function definition that appears outside of the class 
definition are added to the set of default arguments provided by the member function 
declaration in the class definition [..]