How can I make this variadic template code shorter using features from C++14 and C++1z?

Question

This is a code snippet that I am going to use in order to check whether the variadic template types are unique:

template 
struct is_one_of         


        

Answer 1

#include 

template 
constexpr bool is_one_of = (std::is_same{} || ...);

template 
constexpr bool is_unique = true;

template 
constexpr bool is_unique = is_unique && !is_one_of;

DEMO