D's Destructors are What Scott Meyers Warned Us About

[sarn]

On Sunday, 27 May 2018 at 22:27:52 UTC, sarn wrote:
> I've been thinking this through a bit, and here's what I've got 
> so far:

Here's a tweak that should be implementable without any language 
changes:

Instead of trying to detect an empty destructor, we use a UDA on 
the class --- call it BaseObject or something.  A 
BaseObject-marked class is meant to be something like Andre's 
ProtoObject, or a custom alternative base.  It must not define a 
destructor or include members with destructors (could relax this 
in future but works for now), and must only inherit from other 
BaseObject-marked classes.

With that, __vdtor could be implemented using a template mixin.  
For a BaseObject class, that would generate an empty virtual 
__vdtor.  For other classes, it would call __xdtor and then 
(non-virtually) call __vdtor for the superclass as long as it's 
not a BaseObject class.

Can anyone see something I've missed?  I think it works with the 
current type system, makes Andre's ProtoObject possible while 
supporting subclassing with @nogc or whatever, and gives us safe 
class destructors that could be compatible with C++.