Solution to "statement is not reachable" depending on template variables?

[Moritz Maxeiner via Digitalmars-d-learn]

On Sunday, 18 June 2017 at 11:11:59 UTC, Johan Engelen wrote:
> On Sunday, 18 June 2017 at 09:56:50 UTC, Steven Schveighoffer 
> wrote:
>> On Sunday, 18 June 2017 at 09:28:57 UTC, Johan Engelen wrote:
>>> Reviving this thread to see whether anything has changed on 
>>> the topic.
>>>
>>
>> If Timon gets static for each into the language, it can look a 
>> little better.
>
> Can you help me understand what you mean? How will it improve 
> things? (static foreach would disable the "statement not 
> reachable" analysis?)

The new static foreach is AFAIK supposed to execute the loop 
instead of unrolling it, i.e. the expansion of

---
foreach (i, U; T) {
     static if (is(U == bool)) {
         return false;
     }
}
return true;
---

to

---
     static if (is(U1 == bool)) {
         return false;
     }
     static if (is(U2 == bool)) {
         return false;
     }
     ...
return true;
---

, which triggers that "statement is not reachable"  if at least 
one of U1,U2,... = T is bool, will not occur if you instead use 
`static foreach (i, U; T)`.