Type of ‘this’ pointer in C++

In C++, this pointer is passed as a hidden argument to all non-static member function calls. The type of this depends upon function declaration. If the member function of a class X is declared const, the type of this is const X* (see code 1 below), if the member function is declared volatile, the type of this is volatile X* (see code 2 below), and if the member function is declared const volatile, the type of this is const volatile X* (see code 3 below).

Code 1

#include<iostream>
class X {
   void fun() const {
    // this is passed as hidden argument to fun(). 
    // Type of this is const X* 
    }
};

Code 2

#include<iostream>
class X {
   void fun() volatile {
     // this is passed as hidden argument to fun(). 
     // Type of this is volatile X* 
    }
};

Code 3

#include<iostream>
class X {
   void fun() const volatile {
     // this is passed as hidden argument to fun(). 
     // Type of this is const volatile X* 
    }
};

References:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1905.pdf

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