Path: utzoo!telly!ddsw1!lll-winken!killer!mit-eddie!bloom-beacon!tut.cis.ohio-state.edu!PARIS.ICS.UCI.EDU!schmidt%crimee.ics.uci.edu
From: schmidt%crimee.ics.uci.edu@PARIS.ICS.UCI.EDU ("Douglas C. Schmidt")
Newsgroups: gnu.g++.bug
Subject: protection error with g++ 1.32
Message-ID: <8901021714.aa10397@PARIS.ICS.UCI.EDU>
Date: 3 Jan 89 01:14:07 GMT
Sender: daemon@tut.cis.ohio-state.edu
Distribution: gnu
Organization: GNUs Not Usenet
Lines: 41


Hi,

  The following short C++ program demonstrates a problem with g++
1.32's handling of private constructors in derived types:

----------------------------------------
class Base {
public:
   char *Protex;
   Base ( char *s ) {
      Protex = s;
   }
};

class Derived : public Base {
   Derived ( Base &b ) : ( b ) {
      printf ( "error: this is a private constructor!\n" );
   } 
};

int main ( int argc, char *argv [ ] ) {
   Base B ( argv [ 0 ] );
   Derived D ( B ); // this is an improper use of a private constructor
}
----------------------------------------

The variable definition and initialization for

  Derived D ( B );

makes an illicit call to a private constructor.  G++ 1.32 does not
complain about this.  AT&T cfront 1.2.1 correctly reports:

----------------------------------------
"bug.c", line 18: error:  Derived::Derived() is private 
----------------------------------------

more to come....!

Doug