C++ syntax for explicit specialization of a template function in a template class?

Question

I have code which works in VC9 (Microsoft Visual C++ 2008 SP1) but not in GCC 4.2 (on Mac):

struct tag {};  template< typename T > struct C {        template< typename Tag >     void f( T );                 // declaration only      template<>     inline void f< tag >( T ) {} // ERROR: explicit specialization in };                               // non-namespace scope 'structC<T>' 

I understand that GCC would like me to move my explicit specialization outside the class but I can't figure out the syntax. Any ideas?

// the following is not correct syntax, what is? template< typename T > template<> inline void C< T >::f< tag >( T ) {} 

Answer 1

You can't specialize a member function without explicitly specializing the containing class.
What you can do however is forward calls to a member function of a partially specialized type:

template<class T, class Tag> struct helper {     static void f(T);    };  template<class T> struct helper<T, tag1> {     static void f(T) {} };  template<class T> struct C {     // ...     template<class Tag>     void foo(T t) {         helper<T, Tag>::f(t);     } };