Hello all,

 Before all i would like to aske for replies by mail,
 I will post a summery.

 Here is my problem for which I need your help:
 I have 4 classes: SA
     SB sublcass of SA
     A
     B  subclass of A

 class SA    class A
 {     {
 public:     }
 void F (A PAR);
 }

 class SB : public SA   class B : public A
 {     {
 public:     }
 void F (B PAR);
 }

 So SB redefines the F function defined in SA but the parameter
 type of SB:F is B a subtype of the parameter of SA::F.

 The bodies of theFs are:
 void SA::F (A PAR) { cout << "F of SA" << endl; }
 void SB::F (B PAR) { cout << "F of SA" << endl; }

 And my main is:
 Main () {

 sa osa;   // line 1
 sb osb;    // line 2

 a oa;   // line 3
 b ob;   // line 4

 osa.f(oa);  // line 5
 osa.f(ob);  // line 6

 osb.f(oa);  // line 7
 osb.f(ob);  // line 8
 }


 When I compile with a ATT c++ compiler I get the following message:
 "E#669 cannot make a structure B from a A" for the line 7.

 But when I compile with g++ version 2.4.5 it compiles and this
 is the output:
 f of sa  // call of line 5
 f of sa  // call of line 6
 f of sa  // call of line 7
 f of sb  // call of line 8
 Which measn that the call of F on an object of type SB with
 a parameter of type A calls the F of SA.

 I agree with the first policy (the ATT c++ compiler).

 My questions are:
 - which policy is the correct one? the ATT c++ one or the g++ one?
 - is there a bug in g++?
 - is there a bug in the ATT c++ compiler?
 - what the standard recommands?

 Please reply by mail I will post a summery.

Many thanks in advance,
Cheers,
Arash Khodabandeh,

  CERN ECP, Programming Techniques Group, CH-1211 GENEVE 23,
  Phone: + 41 22 767 8072, Fax: + 41 22 767 8730,
  Email: Arash.Khodabandeh@cern.ch khoda@ptsun00.cern.ch, akhodaba@cernvax.cern.ch.