Re: Using "this" in a base initializer list?

From:

James Kanze <james.kanze@gmail.com>

Newsgroups:

comp.lang.c++

Date:

8 May 2007 08:51:44 -0700

Message-ID:

<1178639504.536048.268370@e51g2000hsg.googlegroups.com>

On May 8, 3:25 pm, "Victor Bazarov" <v.Abaza...@comAcast.net> wrote:

Angel Tsankov wrote:

Hello! Is the following code illformed or does it yield undefined
behaviour:

class a
{};

class b
{
public:

b(a&){}
};

class c: private a, private b
{
public:
c():b(*this){}
};

Neither. The code is fine.

Are you sure? Throw in some virtual inheritance, and it core
dumps with Sun CC. And =A73.8 of the standard explicitly says
that:

    Before the lifetime of an object has started but after
    the storage which the object will occupy has been
    allocated39) or, after the lifetime of an object has
    ended and before the storage which the object occupied
    is reused or released, any pointer that refers to the
    storage location where the object will be or was located
    may be used but only in limited ways.[...] If the
    object will be or was of a non-POD class type, the
    program has undefined behavior if
    [...]
     -- the pointer is implicitly converted (4.10) to a
        pointer to a base class type,

(Quoted from the April, 2006 draft. The only one I have
handy here. But I don't think the text in question has
changed since the original standard.)

I think that there are some special rules concerning the
this pointer, but I can't find them off hand. If you can
find them, and point them out to me, I'd be very happy.
I really want this to be defined.

--
James Kanze (Gabi Software) email: james.kanze@gmail.com
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