Fix deprecation: preview=in

[Inkrementator]

Please check lines that contain "REVIEW" in a comment, they need verification and I suspect you can do it faster than me.

Unit tests fail to compile. The offending line looked intentional to me, so I left it in.

[Inkrementator]

Since "in" seems to pass the parameters by value, which is not what you did beforehand, declaring them all "const ref" might be more desirable. I don't know if this matters

[Inkrementator]

Relevant dmd release for the deprecation:

https://dlang.org/changelog/2.104.0.html

[Inkrementator]

I forced pushed a new version that passes unittests with SKIP_IPv6_LOOPBACK_TESTS=1 because my system doesn't support it.

[schveiguy]

I really need to get the CI working again on this...

[Inkrementator]

Btw I think I ticked some checkbox that you can just make changes to my PR. It might be faster for you to make small changes yourself rather than commenting them, I don't know how convenient this system is.

[schveiguy]

Btw I think I ticked some checkbox that you can just make changes to my PR. It might be faster for you to make small changes yourself rather than commenting them, I don't know how convenient this system is.

Yeah, thanks. I don't really know how to use that system easily... My understanding is I have to use the gh command line tool, or sign up for something else.

I'm OK to do this if you feel like dropping it. I actually have to get it done either way, as others have separately requested me to fix io for preview=in. You've helped me a lot already!

[schveiguy]

Actually, I think this is good to go. I just have to test it, or get the CI to start working...

[Inkrementator]

I'm fine helping like this, just want to make sure you don't think I'll be offended if you throw it all out and do it your own way.

[schveiguy]

hehe, thanks. Yes, I'm also a not-get-offended type of person.

[schveiguy]

I tested locally, passed all existing unittests. Good enough for me.