Make StatusCode allow 600-999

[quininer]

Also change StatusCode to NonZeroU16, I think this will help performance.

see https://rust.godbolt.org/z/1Evhbx

[Matthias247]

You should describe the use-case for this. The addition of status codes with printable representations will increase the binary (rough estimate: 400 status codes * (3 bytes len + 8 bytes length indicator + align = 16bytes) = 6kB).
So this shouldn't be done unless there is also a reason for it.

I guess one could be proxying, where an upstream return an arbitrary 3-digit number, which is not bounded up to 599?

[quininer]

Many cases have been cited in #144 . About size, I will try to make it compact. (3 * 900) = 2700, this will be smaller than it is now.

[geota]

@quininer @Matthias247 is there an update to getting this merged? I have a vested interest to get this merged and could try to pick this up if @quininer is unable to finish off the PR, but I don't want to step on any toes.

[seanmonstar]

I'd tentative consider merging, putting aside my strong feeling that servers shouldn't do this.

I think the issue of added binary size is valid. I don't know a great way to fix that, perhaps StatusCode::as_str should go away completely?

[quininer]

I think size issue should not block this PR, because this PR has made size smaller than before.

[geota]

@seanmonstar @Matthias247 can we figure out what the next steps on this PR should be to get this merged? Is size an issue? @quininer made the size smaller than before, so I feel that any other improvements here should be left to a future PR.

One thing to consider is folks who are trying to use this library in proxies where they have no control over what origins decide to return. I'd tentatively consider merging, putting aside my strong feeling that servers shouldn't do this.

[quininer]

Close by #443