C++ : Why cant static functions be declared as const or volatile or const volatile [duplicate]

Question

Possible Duplicate:
C++ - Why static member function can’t be created with ‘const’ qualifier

Was curious to know the reason why static member functions cant be declared as const or volatile or const volatile ?

#include<iostream>

class Test 
{     
   static void fun() const 
   { // compiler error
       return;
   }
};

Answer 1

The cv-modifiers of the member functions correspond to the qualification of the hidden this parameter.

static functions have no this parameter. Therefore, they need no cv-qualifiers. So it was decided (IMHO rightly, as otherwise, it would have no meaning) to disallow them on static functions.

BTW static member functions can't also be virtual, pure (=0), deleted, defaulted, && etc.

Answer 2

Because that's what the standard says:

9.4.1 Static member functions [class.static.mfct]

2) [ Note: A static member function does not have a this pointer (9.3.2). —end note ] A static member function shall not be virtual. There shall not be a static and a non-static member function with the same name and the same parameter types (13.1). A static member function shall not be declared const, volatile, or const volatile. (emphasis mine)

The reason for this is that a const (or volatile or virtual) static method wouldn't make sense (in the traditional sense, see below). For example, const implies you can't modify the object's members, but in the case of statics, there's no object to talk about.

You could argue that a const static could apply to other static members, but this option was regarded as pointless.