extern(C++) classes; dtor must go in vtable

[Steven Schveighoffer]

On 5/21/18 6:26 PM, Manu wrote:
> On 21 May 2018 at 14:53, Jonathan M Davis via Digitalmars-d
> <digitalmars-d at puremagic.com> wrote:
>> On Monday, May 21, 2018 14:33:44 Manu via Digitalmars-d wrote:
>>> How do virtual destructors work in normal D classes?
>>
>> It is my understanding that destructors in D are never virtual but rather
>> that the runtime handles calling them correctly.
> 
> Can someone please elaborate on this?
> I want to know exactly what this means in practise.
> 

What he means by never virtual is *ALWAYS* virtual ;) At least in the 
sense of virtual C++ destructors, not ordinary virtual functions.

Here is what the runtime does:

https://github.com/dlang/druntime/blob/38d784a8acd9cfe6ff4dadac6883a40f392f7353/src/rt/lifetime.d#L1380

In essence, each classinfo has it's "local" destructor, which is the 
code you put inside the ~this() function. It runs them in the correct 
order (most derived first).

But it's always virtual, because it uses the classinfo stored in the 
object reference, not the concrete type.

I think what Jonathan meant is that you can't override the base 
destructor like an ordinary virtual function, but I think this is par 
for the course on virtual destructors.

-Steve