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From: schmidt@siam.ics.uci.edu (Doug Schmidt)
Newsgroups: gnu.g++.bug
Subject: Re: Virtual Destructor Bug in 1.31.0
Message-ID: <5394@paris.ics.uci.edu>
Date: 25 Jan 89 21:51:25 GMT
References: <8901251939.AA08887@sfu_cmpt.cs.sfu.ca>
Sender: news@paris.ics.uci.edu
Reply-To: Doug Schmidt <schmidt@siam.ics.uci.edu>
Distribution: gnu
Organization: University of California at Irvine: ICS Dept.
Lines: 56

In article <8901251939.AA08887@sfu_cmpt.cs.sfu.ca> kim@cs.sfu.ca writes:
++In using g++ (version 1.31.0) we have encountered a serious problem in the
++code generated for virtual destructors.
++
++Criteria: The following code results in runtime infinite recursion on ~derived:
++
++    #include <stdio.h>
++
++    class base
++      {
++        base();
++        virtual ~base();
++      };
++      
++    inline base::base() {}
++    inline base::~base() {}
++    
++    class derived : base
++      {
++        derived();
++        ~derived();
++      };
++      
++    inline derived::derived() : () {}
++    inline derived::~derived() { fputc('*',stderr); }
++    
++    main()
++      {
++         derived a;
++      }
++ 

This bug is fixed in GNU G++ 1.32.  However, your code is also
incorrect, since the constructor's and destructor's are declared in
the ``private'' section of class base and class derived, by the
default visibility rules.

Here's what a beta version of g++ 1.32.1 says:

----------------------------------------
In function struct derived *derived::derived ():
virt-dest-bug.1.32.cc:9: the constructor struct base *base::base () is private
virt-dest-bug.1.32.cc:18: no default constructor defined for type `base'
In function int main ():
virt-dest-bug.1.32.cc:18: the constructor struct derived *derived::derived () is private
virt-dest-bug.1.32.cc:23: no default constructor defined for type `derived'
----------------------------------------

When I added the keyword ``public'' to the classes the program ran as expected.

Doug
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