[boost] inherited operators

From: Jason Hise (chaos_at_[hidden])
Date: 2005-02-17 00:48:35

Sometimes I like to play around with obscure code, just to see what it 
does.  The following really surprised me:

#include <iostream>

struct A
{
public:
    bool operator == ( const A & rhs )
    {
        std::cout << "A\n";
        return true;
    }
};

struct B
{
public:
    bool operator == ( const B & rhs )
    {
        std::cout << "B\n";
        return false;
    }
};

struct C : public A, public B {  };

int main (  )
{
    C c1, c2;
    if ( c1 == c2 ) std::cout << "Equal\n";
    return 0;
}

Compiled on MSVC 7.1, this outputs:
A
Equal

I would have expected this code not to compile at all, because the == 
overload seems ambiguous.  Is this result standards conforming?  If not, 
what would the standards conforming result be?  Does this fall into the 
realm of undefined behavior?

-Jason