[Optimization] Speculatively not calling invariant on class objects

[Steven Schveighoffer via Digitalmars-d]

On 8/13/15 2:25 PM, Iain Buclaw via Digitalmars-d wrote:

>
> class A { invariant { } }
> class B : A { }
> class C : B { invariant { } }
>
> B b = new C();  // We can only discover that 'b' is a C object at runtime.
>
>     I thought invariant was like ctor/dtor, the most derived
>     automatically calls the base version.
>
>
> Nope, it only calls it's own invariants.  Calling all derived invariants
> is what _d_invariant is for.

I envisioned C.invariant would inject a call to A.invariant, and that 
invariant would occupy a vtable slot.

-Steve