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

Answer 1

Static member functions are global, free functions that do not depend on an object (i.e. a class instance). The CV qualifiers on non-static member functions refer to the type of the object on which they are called, and this notion simply doesn't apply to static member functions.

Example:

struct Foo
{
    void f();        // Overload #1
    void f() const;  // Overload #2
    static void g();
};

int main()
{
    Foo x;

    x.f();                            // calls overload #1
    static_cast(x).f();  // calls overload #2

    Foo::g();                         // does not know about any instance!

    x.g();                            // same as Foo::g(); "x" is a red herring
}