Build fails with "unstable feature" error in rkv dependency

[kfogel]

I tried doing cargo build (of master at commit ef2e4eb) and got this error:

  $ cargo build 
      Updating crates.io index
   Downloading crates ...
    Downloaded chrono v0.4.6
    Downloaded encoding_rs v0.8.17
    [...]
     Compiling zip v0.5.2
     Compiling serde_json v1.0.39
     Compiling rkv v0.9.6
  error[E0658]: use of unstable library feature 'try_from' (see issue #33417)
     --> /home/kfogel/.cargo/registry/src/github.com-1ecc6299db9ec823/rkv-0.9.6/src/error.rs:166:11
      |
  166 | impl From<::std::num::TryFromIntError> for MigrateError {
      |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  
  error[E0658]: use of unstable library feature 'try_from' (see issue #33417)
    --> /home/kfogel/.cargo/registry/src/github.com-1ecc6299db9ec823/rkv-0.9.6/src/migrate.rs:78:5
     |
  78 |     convert::TryFrom,
     |     ^^^^^^^^^^^^^^^^
  
  [...many more similar error lines...]
  
  error: aborting due to 12 previous errors
  
  For more information about this error, try `rustc --explain E0658`.
  error: Could not compile `rkv`.
  warning: build failed, waiting for other jobs to finish...
  error: build failed
  $ 

I don't know much Rust, but it looks like rkv is using an unstable feature (rust bug 33417 has more about it), and that since rga depends on rkv, this affects the rga build too. I ran rustc --explain E0658 and got some information about how to solve the problem -- presumably those solutions would have to be implemented upstream in rkv, if we wanted to solve this for everyone, or else I'd have either build a modified rkv locally or get the nightly version of rustc to do the build I just tried to do.

I'm not sure what ways might be available to solve this within rga. Ideas welcome; like I said, I don't know Rust that well.

Anyway, this was all along the way to submitting a PR for README.md to add installation instructions. I'll submit that PR, and then in its commentary mention this issue.

[phiresky]

It should actually build on Rust stable, in fact the CI is checking that. Can you say which Rust version you are on? (rustc --version). And if you are not on 1.35, use rustup update to update.

[kfogel]

rustc 1.32.0

Thanks; I'll try the update. I was just using whatever the latest rustc in Debian GNU/Linux 'testing' distro is -- which is apparently not quite up-to-date with upstream stable.

[hldh214]

i meet the same issue and solved with rustup install nightly

[sersorrel]

You don't need nightly to solve this, just Rust 1.34 or higher.

[phiresky]

I've modified the readme to make it clearer you need 1.35+. I don't think I want to support older Rust versions

[kfogel]

Thanks everyone for the followups. I'll get 1.35 or higher and use that.