Combine it with "virtual" multiple inheritance and all bets are off..

// Robin

On Thu, Nov 14, 2024, 14:16 Egor via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> If I'm not mistaken, multiple inheritance can cause the vtable to be at
> a non-zero offset on all compilers (if the first base isn't polymorphic).
>
> 14.11.2024 16:42, Frederick Virchanza Gotham via Std-Proposals пишет:
> > The C++ programming language is held back by the Microsoft compiler's
> > implementation of VTables. Every other C++ compiler places the pointer
> > to the VTable right at the beginning of the object, but the Microsoft
> > compiler sometimes places it elsewhere. This has the following
> > consequences:
> >
> > (1) Cannot use dynamic_cast on a void*
> >
> > Assuming that we have a void* pointer that points to a polymorphic
> > object, we would be able to use dynamic_cast on it to perform a
> > side-cast or down-cast (or to get the most-derived object).
> >
> > (2) Cannot get the type_info from a void*
> >
> > Assuming that we have a void* pointer that points to a polymorphic
> > object, we would be able to get its type_info.
> >
> > I think the committee should consider giving Microsoft a certain
> > amount of time to change this. I realise that the Standard doesn't
> > mention 'Microsoft' in its text but the committee could make the
> > decision that in C++36, the above two points are possible (which would
> > mean that MS have to change their ABI by then).
> --
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