Having trouble with template classes having template member functions

In my experimentation with templates I've come across a confusing predicament. I'm defining a templated struct `F` who default argument is `int`. It has a templated member function `g`. I'm defining it below the struct definition. I figured this was the correct way to go about it, however, I receive an error. And only one error: prog.cpp:9:62: error: default argument for template parameter for class enclosing 'void F< >::g()' ``` template <typename = int> struct F { template <typename> void g(); }; template <typename T = int> template <typename> void F<T>::g() {} int main() { F<>f; } ``` It's quite vague. I couldn't exactly understand what it means. So I tried changing some things around. I figured it was the default template arguments for the definition of `F`. So I changed: ``` template <typename = int> struct F { ``` to ``` template <typename T = int> struct F { ``` I also tried giving `g` template arguments: ``` template <typename T = int> template <typename U> void F<T>::g<U>() {} ``` But then I received the errors: prog.cpp:9:67: error: function template partial specialization 'g' is not allowed prog.cpp:9:67: error: default argument for template parameter for class enclosing 'void F::g()' I even tried specifying that `g` was a template function: ``` template <typename T = int> template <typename U> void F<T>::template g<U>() {} ``` But it didn't help. What am I doing wrong?