What is the best way to create a specialization-only function template?

Question

Is there a better way to do the following?

#include 

template 
T Bar();

template <>
int Bar() { return 3; }
         


        

Answer 1

This could work:

template 
T Bar() {
  T::ERROR_invalid_template_argument_;
}

template <>
int Bar() { return 3; }

You could also use the highest size possible if you're afraid of using 0:

  static_assert(sizeof(T) == -1, "No specialization");