Divide & Conquer divides, but doesn't conquer

[Timon Gehr]

On 25.05.20 19:25, Stefan Koch wrote:
> On Monday, 25 May 2020 at 17:23:50 UTC, Timon Gehr wrote:
>> On 25.05.20 19:21, Stefan Koch wrote:
>>> On Monday, 25 May 2020 at 17:16:12 UTC, Timon Gehr wrote:
>>>> On 25.05.20 18:57, Stefan Koch wrote:
>>>>> On Monday, 25 May 2020 at 16:46:16 UTC, Timon Gehr wrote:
>>>>>> [...]
>>>>>
>>>>> What do you do about the scopes?
>>>>
>>>> Nothing special. Why would I have to?
>>>
>>> You need a manifest constant for you IV (induction variable), no?
>>> Which would clash with the one previously introduced.
>>>
>>
>> Sure, so I create one forwarding scope per iteration. This is not 
>> particularly expensive, it's constant overhead per iteration.
> 
> Since Forwarding scopes where not in the language before you introduced 
> static if.
> Could you give a quick explanation how they work?
> 

It's a scope that forwards new symbols to its parent scope on insertion. 
This way, each iteration of the `static foreach` will have its own local 
scope with distinct loop variables, but any declarations that are 
generated in the `static foreach` body will skip this scope and instead 
populate the parent scope. (As an experiment, the original 
implementation also had `__local` declarations to insert symbols into 
the local scope without forwarding.)