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From: mball@cod.NOSC.MIL (Michael S. Ball)
Newsgroups: comp.lang.c++
Subject: Re: Virtual destructors
Keywords: virtual destructor portability
Message-ID: <1431@cod.NOSC.MIL>
Date: 2 Mar 89 22:25:02 GMT
References: <551@hrc63.co.uk> <1430@cod.NOSC.MIL> <101@riunite.ACA.MCC.COM>
Reply-To: mball@cod.nosc.mil.UUCP (Michael S. Ball)
Organization: Naval Ocean Systems Center, San Diego
Lines: 31

In article <101@riunite.ACA.MCC.COM> rfg@riunite.UUCP (Ron Guilmette) writes:
>In article <1430@cod.NOSC.MIL> mball@cod.nosc.mil.UUCP (Michael S. Ball) writes:
>>In article <551@hrc63.co.uk> pj@hrc63.co.uk (Mr P Johnson "Baddow") writes:
>>>In Oregon C++ (for Suns) v 1.1, it is possible to declare the base destructor
>>>as virtual.  This then ensures that the appropriate destructor is called for
>>>any derived classes provided that the _derived_class_has_a_destructor_.  If
>>>the derived class has no explicit destructor then any member destructors will
>>>not be called (rather than being called implicitly as they would be normally).
>>
>>I believe this is a bug.
>
>I'm not sure what the "correct" semantics are myself, but I don't think it
>is a bug.

It is not a question of whether virtual destructors are allowed.  They are,
and should behave like all other virtual functions, which is to say that
references to them will normally go through the virtual table.  The problem,
which is what I said was a bug, is that the destructors generated by the
compiler were NOT being treated as virtual even though the base class
destructor WAS virtual.  Since a user destructor for the derived class will be
virtual, it seems only logical that the compiler-generated one will be as
well.  It is not being so treated in the current version Oregon C++.  I
have no idea what G++ does in that situation, and the data you included
does not cover this case.

Mike Ball
TauMetric Corporation
1094 Cudahy Pl. Ste 302
San Diego, CA 92110
(619)275-6381
mball@cod.nosc.mil