Rust

This article is about the Rust programming language. There are 3 methods to use the rust compiler and toolchain in Nix/NixOS: via nixpkgs, via rustup, or with unofficial overlays on nixpkgs. Installing via nixpkgs is the nix-iest way to use rust, but there are valid reasons to use any approach.

Installing via nixpkgs

The cargo and rustc derivations provide the rust toolchain in nixpkgs. A pro of using nixpkgs is that it's dead-simple and you get pinned versions, deterministic builds in nix-shell, etc. However, nixpkgs only maintains a single version of the rust stable toolchain, so if you require a nightly toolchain or require switching between multiple toolchains then this approach may not be for you.

Here's an example shell.nix:

let
  # Pinned nixpkgs, deterministic. Last updated: 2/12/21.
  pkgs = import (fetchTarball("https://github.com/NixOS/nixpkgs/archive/a58a0b5098f0c2a389ee70eb69422a052982d990.tar.gz")) {};

  # Rolling updates, not deterministic.
  # pkgs = import (fetchTarball("channel:nixpkgs-unstable")) {};
in pkgs.mkShell {
  buildInputs = [ pkgs.cargo pkgs.rustc ];
}

VSCode integration

The rust-lang.rust and matklad.rust-analyzer VSCode extensions offer rust support. However, you'll need a few more ingredients to get everything working:

let
  # Pinned nixpkgs, deterministic. Last updated: 2/12/21.
  pkgs = import (fetchTarball("https://github.com/NixOS/nixpkgs/archive/a58a0b5098f0c2a389ee70eb69422a052982d990.tar.gz")) {};

  # Rolling updates, not deterministic.
  # pkgs = import (fetchTarball("channel:nixpkgs-unstable")) {};
in pkgs.mkShell {
  buildInputs = [ 
    pkgs.cargo 
    pkgs.rustc
    pkgs.rustfmt
  ];

  # See https://discourse.nixos.org/t/rust-src-not-found-and-other-misadventures-of-developing-rust-on-nixos/11570/3?u=samuela.
  RUST_SRC_PATH = "${pkgs.rust.packages.stable.rustPlatform.rustLibSrc}";
}

You can use the arrterian.nix-env-selector extension to enable your nix-shell inside VSCode and have these settings picked up by other extensions.

Installation via rustup

The rustup tool is maintained by the rust community and offers and interface to install and switch between rust toolchains. In this scenario, rustup handles the "package management" of rust toolchains and places them in $PATH. Nixpkgs offers rustup via the rustup derivation. More info on using rustup can be found on their official website: https://rustup.rs/.

Unofficial overlays

TODO

Rust Nightlies

Either use Rust overlay or rustup to get install Rust nightlies.

Neovim Completion

Racer completion can be configured using the following snippet:

(neovim.override {
  configure = {
    customRC = ''
      if filereadable($HOME . "/.vimrc")
        source ~/.vimrc
      endif
      let $RUST_SRC_PATH = '${stdenv.mkDerivation {
        inherit (rustc) src;
        inherit (rustc.src) name;
        phases = ["unpackPhase" "installPhase"];
        installPhase = ''cp -r library $out'';
      }}'
    '';
    packages.nixbundle.start = with vimPlugins; [
      nvim-completion-manager
      nvim-cm-racer
    ];
  };
})