New release?

[g0hl1n]

Hi @eldruin,
thanks for stepping up as maintainer.

Would you mind tagging a new release for serialport-rs?
My project is waiting for a tag containing the new nix version 😉

Thanks & regards

[eldruin]

Sure, however, it seems no changes have been noted in the changelog since last release.
Would you mind going through PRs merged since then and adding short notes about them in the changelog?

[mlsvrts]

Just a note that we have at least one (and sort-of two) breaking changes currently in the main branch:

• The updated nix version is technically breaking, if unlikely to cause problems
• There's a new member in a public struct (UsbPortInfo.interface)

We could target the master branch as 5.0.0-alpha and back port a 4.X release without breaking changes.

Note that we could probably feature-gate the UsbPortInfo change to make it non-breaking, but I don't know if we have an easy solution for the nix update...

[eldruin]

Thanks for noticing that @mlsvrts.
Looking at the nix issue, I could not find any nix types in the library interface quickly skimming the docs (although I may have missed some).
If this is the case, I understand updating nix should not be a breaking change. Or has there been a behavioral change inside nix?

[mlsvrts]

This is per @jannic (thanks!):

That's a limitation of semver-checks. See obi1kenobi/cargo-semver-checks#5, bullet point "upgrading to new major version of dependency while exporting a type that implements a trait from the dependency".

And yes, I think we are exporting such a type. impl From<nix::Error> for Error in error.rs.

Not literally a "trait from the dependency", but a trait which includes nix in its generic type.

I guess this won't cause any actual breakage in practice, though: I don't see any reason why external code should try to convert a nix::Error into a serialport::Error. This code is probably only used from inside the serialport crate.

This code works if the version of nix is identical:

fn main() {
    let nix_error: nix::Error = nix::Error::UnknownErrno;
    let serialport_error: serialport::Error = nix_error.into();
    println!("{serialport_error:?}");
}

However, if the binary crate and serialport use different versions of nix, compiling fails:

error[E0277]: the trait bound `serialport::Error: From<Errno>` is not satisfied
 --> src/main.rs:3:57
  |
3 |     let serialport_error: serialport::Error = nix_error.into();
  |                                                         ^^^^ the trait `From<Errno>` is not implemented for `serialport::Error`
  |
  = help: the following other types implement trait `From<T>`:
            <serialport::Error as From<libudev::error::Error>>
            <serialport::Error as From<nix::errno::consts::Errno>>
            <serialport::Error as From<std::io::Error>>
  = note: required for `Errno` to implement `Into<serialport::Error>`

So I'm quite sure this technically is a breaking change, but in practice it could be ignored.

[eldruin]

Interesting! Thank you for looking into it.

[sirhcel]

What about a maintenance release with simply omitting the breaking changes to UsbPortInfo and ignoring the issue with nix as proposed in #92 (comment)?

I'm starting a release branch with #100.

[sirhcel]

Inching forward with #103.

[sirhcel]

4.2.1 got released on crates.io. A big thank you to all contributers and the fruitful discussions.