From: "Johan Nilsson" <[EMAIL PROTECTED]>
>
> "Peter Dimov" <[EMAIL PROTECTED]> wrote in message
> 00bb01c2a046$671b1c20$1d00a8c0@pdimov2">news:00bb01c2a046$671b1c20$1d00a8c0@pdimov2...
> > From: "Johan Nilsson" <[EMAIL PROTECTED]>
> > [...]
> > > template<typename T>
> > > T* dynamic_void_cast(void* pv)
> > > {
> > > struct rtti_obj__
> > > {
> > > virtual ~rtti_obj__() = 0;
> > > };
> > >
> > > rtti_obj__* pro = static_cast<rtti_obj__*>(pv);
> > >
> > > try
> > > {
> > > return dynamic_cast<T*>(pro);
> > > }
> >
> > This is not required to work. T's vtable pointer is not guaranteed to be
> at
> > offset 0.
Actually I meant *pv's vtable pointer here.
> But I thought that it _might_ be required to be at the same offset for T
as
> for rtti_obj. For that part, IIRC, a vtable isn't required at all, or?
Try it (on several compilers, as some do put the vptr at offset 0.)
struct X { int n; };
struct Y: public X { virtual ~Y() {} };
Y+0: X::n
Y+4: vptr
rtti_obj__+0: vptr
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