Using core.reflect to check for unused parameters

[user1234]

On Friday, 3 September 2021 at 15:47:16 UTC, Stefan Koch wrote:
> On Friday, 3 September 2021 at 15:32:59 UTC, user1234 wrote:
>> On Friday, 3 September 2021 at 14:45:20 UTC, Stefan Koch wrote:
>>> On Friday, 3 September 2021 at 13:02:37 UTC, user1234 wrote:
>>>> On Thursday, 2 September 2021 at 21:27:33 UTC, Stefan Koch 
>>>> wrote:
>>>>> [...]
>>>>> now this visitor will reliably detect usage of parameters.
>>>>
>>>> BTW, I'm curious to know how this can work. Should not 
>>>> VarExp (and not VarDecl) be overridden to mark ?
>>>
>>> VerExps have a VarDecl member.
>>> which the transitive visitor looks into for you.
>>>
>>> You could look at VarExps but I chose to look into VarDecls 
>>> instead.
>>
>> so FuncDeclaration parameters are not visited, that's why that 
>> works ?
>> only bodies are visited ?
>
> Exactly this works because of this line.
> `(cast()fd.fbody).accept(marker);`

indeed I've missed that line

> I am starting the visitor at the body of the function.
> And since there no back-edge to the function declaration it 
> works.
> If you have a back-edge to the function declaration for example 
> in recursive call it would stop working.
> So visiting the VarExp is a better idea.

Yes and no. It's better _as example_, so that we can see clearly 
that params are marked on use. Basically my first answer was 
posted because overridding the visit of VarDecl was confusing.

Otherwise that looks like a convincing example.