Re: Is gcc warning about non-virtual destructor useless?

From:
red floyd <no.spam@here.dude>
Newsgroups:
comp.lang.c++.moderated
Date:
Thu, 23 Aug 2007 10:26:57 CST
Message-ID:
<lp9zi.1539$vU4.702@nlpi068.nbdc.sbc.com>
mail@kirill-mueller.de wrote:

Hi,

I've tested the following example with Visual Studio 2005 and with gcc
4.1.0:

class A {
protected:
   ~A();
};

class B : public A {
public:
   void test() {
      A* a = new B;
      a->~A(); // VS2005: Error C2248: No access to protected
member
      delete a; // VS2005: Error C2248: No access to protected
member
   }
};

Which means, that it's not possible to "delete" a pointer to A*, even
in member functions of classes derived from A. IMHO, this means that
it's perfectly safe to use non-virtual destructors provided that they
are declared as "protected".

Any opinions? How do other compilers behave?


This is correct, per the Standard (I can't quote chapter and verse, though).

Protected means that an instance of B gets to see *it's own* A protected
members. It can't see any other A's protected members.

If this isn't a FAQ (and I couldn't find it in the FAQ), it probably
should be.

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