Path: utzoo!attcan!uunet!cs.utexas.edu!asuvax!ncar!mephisto!mcnc!decvax!shlump.nac.dec.com!ashok.dec.com!nadkarni
From: nadkarni@ashok.dec.com
Newsgroups: comp.lang.c++
Subject: Is this a bug ?
Message-ID: <10259@shlump.nac.dec.com>
Date: 13 Apr 90 12:37:07 GMT
Sender: newsdaemon@shlump.nac.dec.com
Organization: Digital Equipment Corporation
Lines: 65


Am I doing something wrong or is this a bug in the compiler ? It appears 
as though the compiler tries to optimize by not copying the virtual table
function pointer when assigning an object to another. Unfortunately,
in this case it does not work. The compiler is Zortech C++ 2.06.
I expected to see the output

C
A
B

and instead saw

A
A
A

Could someone please confirm this is a bug (in my code or the compiler).
---------------------- code follows ------------------
#include <stream.hpp>

class C {
    public:
	virtual void output() {cout << "C\n";}
};

class A : public C {
    public:
	virtual void output() {cout << "A\n";}
};

class B : public C {
    public:
	virtual void output() {cout << "B\n";}
};

union AB {
    class B b;
    class C c;
    class A a;
};

main ()
{
    A a;
    B b;
    C c;
    AB ab;


    ab.c = c;
    ab.c.output();

    ab.a = a;
    ab.a.output();

    ab.b = b;
    ab.b.output();

}

Thanks,

/Ashok Nadkarni
Digital Equipment Corp.