template<class... Types>
void f(typename Types::X... args){

}

struct S{
    typedef int X;
};


int main()
{
    S s1;
    S s2;
    S s3;

    f(1,1,2);
}

error: no matching function for call to 'f'
    f(s1,s2,s3);
    ^
note: candidate function not viable: requires 0 arguments, but 3 were provided
void f(typename Types::X... args){
     ^