using stable channel with rustfmt from nightly

[DanConwayDev]

Does rust-overlay enable using rustfmt from nightly whilst otherwise using the stable toolchain?

With rustup both toolchains can be installed and nightly can be targeted by running cargo +nightly fmt.

#56 (comment) alludes to merging toolchains but I am not clear how this would be achieved.

Thanks for your efforts in creating and maintaining rust-overlay :)

[oxalica]

You can pick one component from nightly toolchain and use lib.hiPrio on it to override others.

[
  (lib.hiPrio rust-bin.nightly."2023-09-01".rustfmt)
  (rust-bin.stable.latest.default.override { /* default toolchain */ })
]

[spikespaz]

I have the same question and find myself unsatisfied with the answer.

      devShells = eachSystem (system:
        let pkgs = pkgsFor.${system};
        in {
          default = pkgs.mkShell {
            strictDeps = true;
            packages = with pkgs; [
              rust-bin.stable.latest.default.override
              (lib.hiPrio (rust-bin.selectLatestNightlyWith (toolchain:
                toolchain.minimal.override { extensions = [ "rustfmt" ]; })))
              pkg-config
              openssl
            ];
          };
        });

Obviously, that derivation would also overwrite rustc, cargo, and rust-std from stable with the nightly version.

I would like to stay up-to-date with the latest available nightly after every nix flake lock --update-input rust-overlay, and do not wish to specify a nightly release date.

[spikespaz]

I don't like what I ended up with because, as you said, it is possible that one of these components doesn't build with the latest nightly.

devShells = eachSystem (system:
  let pkgs = pkgsFor.${system};
  in {
    default = pkgs.mkShell {
      strictDeps = true;
      packages = with pkgs; [
        (rust-bin.stable.latest.minimal.override {
          extensions = [ "rust-docs" ];
        })
        (lib.hiPrio rust-bin.nightly.latest.clippy)
        (lib.hiPrio rust-bin.nightly.latest.rustfmt)
        (lib.hiPrio rust-bin.nightly.latest.rust-analyzer)
        pkg-config
        openssl
      ];
    };
  });

I'd like to see something like this:

(rust-bin.selectLatestNightlyWith (toolchain:
  toolchain.minimal.override { extensions = [ "rustfmt" ];
})).extensions.rustfmt

[DanConwayDev]

Thanks @oxalica. I have this working.

Like @spikespaz, I'd prefer not to pin a specific version of nightly and take advantage of selectLatestNightlyWith but that is icing on the cake.

[spikespaz]

When using rust-analyzer from nightly.latest, I see errors like:

error[E0463]: can't find crate for `std`
 --> src/config/mod.rs:3:5
  |
3 | use std::collections::HashMap;
  |     ^^^ can't find crate

and

error[E0514]: found crate `serde` compiled by an incompatible version of rustc
 --> src/config/mod.rs:6:5
  |
6 | use serde::{Deserialize, Serialize};
  |     ^^^^^
  |
  = note: the following crate versions were found:
          crate `serde` compiled by rustc 1.72.0 (5680fa18f 2023-08-23): /home/jacob/Documents/linux-desktop/hyprland-workspace-profiles/target/debug/deps/libserde-cf278766bb3cc9aa.rmeta
  = help: please recompile that crate using this compiler (rustc 1.74.0-nightly (030e4d382 2023-09-10)) (consider running `cargo clean` first)

[spikespaz]

Trying to handle nightly more correctly, attempted this:

devShells = eachSystem (system:
  let pkgs = pkgsFor.${system};
  in {
    default = pkgs.mkShell {
      strictDeps = true;
      packages = with pkgs; [
        (lib.hiPrio (rust-bin.stable.latest.minimal.override {
          extensions = [ "rust-docs" "rust-analyzer" ];
        }))
        (rust-bin.selectLatestNightlyWith (toolchain:
          toolchain.minimal.override {
            extensions = [ "clippy" "rustfmt" ];
          }))

        pkg-config
        openssl
      ];
    };
  });

Same problem though.

[spikespaz]

Using stable clippy, and nightly rustfmt and rust-analyzer works. Sticking with my last attempt, but switched extensions around slightly.

[sveitser]

I'd like to see something like this:

(rust-bin.selectLatestNightlyWith (toolchain:
  toolchain.minimal.override { extensions = [ "rustfmt" ];
})).extensions.rustfmt

@spikespaz There is passthru.availableComponents that seems to accomplish this, not sure if it's a good idea to use that though.

nightlyToolchain = pkgs.rust-bin.selectLatestNightlyWith (toolchain: toolchain.minimal.override {
  extensions = [ "rustfmt" ];
});
...
buildInputs = [
  nightlyToolchain.passthru.availableComponents.rustfmt
  ...
]