Why don't we just FIX the damn vthunk problem?

[Martin v. Loewis]

> Oops, no, I was misreading the code in emit_base_init.  We set the vptrs
> after the base ctors but before the member ctors.  So I once again believe
> that passing via the vptr will work; each ctor would do something like
> 
>   vtable *tmp = (vtable *) this->A::vptr;
>   Base::Base(this, 0);
>   this->A::vptr = tmp[1];

It'll work if it is used consistently throughout the hierarchy. If the
derived class is not recompiled, it does

if (in_chrg)
  A::A();   // now this->A::_vptr is initialized
Base::Base(this,0);
this->A::_vptr = __vt_of_most_derived_class

The recompiled base class would find a vtbl in A::_vptr, not a
vtable*. It would then initialize this->A::vptr with a function
pointer, or crash if tmp[n] is out of range. It'll definitely crash if
the base class constructor does call a virtual function.

Regards,
Martin