Not initialized out argument error

[Tobias Pankrath via Digitalmars-d]

>
> What if x is an "optional" out parameter: EG: something you 
> only set if other conditions are met? Do you want to make sure 
> that x is at least assigned to once, or rather make it an error 
> to have a control path that *doesn't* assign anything to it.
>
> Either way:
> 1. Making it an error to have a control path that doesn't 
> assign to x would be counter productive, as the result would 
> probably end up being code that looks like:
> foo(out int x) {
>    x = 0;
>    ...
> }
> which would defeat the entire point of out.
> 2. Checking the variable is at least used would be kind of the 
> same as checking for unused arguments. I think that'd be fine, 
> provided you could over-ride the warning by not naming your 
> variable:
> foo(out int x){} //Error, x is never assigned to (or used)
> foo(out int){}   //OK!

Today a function with return value but without return statement 
is already an error. Why not return ReturnType.init instead? It's 
absolutely the same.