Possible D2 solution to the upcasting array problem, and a related problem with const and nested arrays

[Stewart Gordon]

Denis Koroskin wrote:
<snip>
> Nice, but I don't like the proposed syntax much, especially these:
> 
> cast(!const BaseClass[])
> cast(!const const(int)[][])
> 
> I believe it would be better to split them into two separate casts as 
> follows:
> 
> BaseClass[] base = cast(BaseClass[])cast(!const)derived;

Won't work.  DerivedClass[] still needs to convert to 
const(BaseClass)[], not to BaseClass[].  Would have to be the more 
long-winded

     BaseClass[] base = cast(!const) cast(const(BaseClass)[]) derived;

and moreover, there'd be no way to do the casts to const(int)[][].

Unless you want cast(!const) to cast to a purely internal intermediate 
type that suppresses const-checking altogether.

Stewart.