A const member function is one which isn’t allowed to modify the members of the object for which it is called. A static member function is one which can’t be called for a specific object.

Thus, the const modifier for a static member function is meaningless, because there is no object associated with the call.

A more detailed explanation of this reason comes from the C programming language. In C, there were no classes and member functions, so all functions were global. A member function call is translated to a global function call. Consider a member function like this:

void foo(int i);

A call like this:

obj.foo(10);

…is translated to this:

foo(&obj, 10);

This means that the member function foo has a hidden first argument of type T*:

void foo(T* const this, int i);

If a member function is const, this is of type const T* const this:

void foo(const T* const this, int i);

Static member functions don’t have such a hidden argument, so there is no this pointer to be const or not.