Question on dynamic casting scope

[Philippe Bouchard <philippeb at corel dot com>]

The following program:
#include <iostream>

int main();

struct A
{
  virtual ~A() {}
};

struct B
{
  virtual ~B() {}
};

struct O : A, private B
{
  friend int main();

  virtual ~O() {}
};

int main()
{
  using namespace std;

  A * p = new O;

  cout << "A * = " << dynamic_cast<A *>(p) << endl;
  cout << "B * = " << dynamic_cast<B *>(p) << endl;
  cout << "O * = " << dynamic_cast<O *>(p) << endl;
}

Outputs:
A * = 0x8049fd0
B * = (nil)
O * = 0x8049fd0

Notice:
If I the inheritance of B into O becomes public, the address of B * becomes 0x8049df4.

Question:
I was wondering why friendship is not affecting dynamic casting scope.

Thank you.
 

begin:vcard 
n:Bouchard;Philippe
x-mozilla-html:FALSE
org:Corel Linux
adr:;;;;;;
version:2.1
email;internet:philippeb@corel.com
title:Software Engineer
x-mozilla-cpt:;0
fn:Philippe Bouchard
end:vcard