Declaring global const objects in the header file

Question

In the Eric Niebler range-v3 library, it provides many headers, each of which has its own global function object. They are all declared the same. It provides a static_const class static_const :

 template<typename T> struct static_const { static constexpr T value {}; }; template<typename T> constexpr T static_const<T>::value; 

And then every function object of type F declared as:

 namespace { constexpr auto&& f = static_const<F>::value; } 

What are the benefits of injecting an object through the static_const template and into an unnamed namespace, rather than just writing:

 static constexpr F f{};