openssl
  ];

  # Set Environment Variables
  RUST_BACKTRACE = 1;
}
```

You should now be able to run the following:

```ShellSession
$ nix-shell --pure
$ cargo build
$ cargo test
```

## Using community maintained Rust toolchains {#using-community-maintained-rust-toolchains}

::: {.note}
The following projects cannot be used within Nixpkgs, since [Import From Derivation](https://nixos.org/manual/nix/unstable/language/import-from-derivation) (IFD) is disallowed in Nixpkgs.
To package things that require Rust nightly, `RUSTC_BOOTSTRAP = true;` can sometimes be used as a hack.
:::

There are two community maintained approaches to Rust toolchain management:
- [oxalica's Rust overlay](https://github.com/oxalica/rust-overlay)
- [fenix](https://github.com/nix-community/fenix)

Despite their names, both projects provides a similar set of packages and overlays under different APIs.

Oxalica's overlay allows you to select a particular Rust version without you providing a hash or a flake input,
but comes with a larger git repository than fenix.

Fenix also provides `rust-analyzer` nightly in addition to the Rust toolchains.

Both oxalica's overlay and fenix better integrate with nix and cache optimizations.
Because of this and ergonomics, either of those community projects
should be preferred to the Mozilla's Rust overlay ([nixpkgs-mozilla](https://github.com/mozilla/nixpkgs-mozilla)).

The following documentation demonstrates examples using fenix and oxalica's Rust overlay
with `nix-shell` and building derivations. More advanced usages like flake usage
are documented in their own repositories.

### Using Rust nightly with `nix-shell` {#using-rust-nightly-with-nix-shell}

Here is a simple `shell.nix` that provides Rust nightly (default profile) using fenix:

```nix
with import <nixpkgs> { };
let
  fenix = callPackage (fetchFromGitHub {
    owner = "nix-community";
    repo = "fenix";
    # commit from: 2023-03-03
    rev = "e2ea04982b892263c4d939f1cc3bf60a9c4deaa1";
    hash = "sha256-AsOim1A8KKtMWIxG+lXh5Q4P2bhOZjoUhFWJ1EuZNNk=";
  }) { };
in
mkShell {
  name = "rust-env";
  nativeBuildInputs = [
    # Note: to use stable, just replace `default` with `stable`
    fenix.default.toolchain

    # Example Build-time Additional Dependencies
    pkg-config
  ];
  buildInputs = [
    # Example Run-time Additional Dependencies
    openssl
  ];

  # Set Environment Variables
  RUST_BACKTRACE = 1;
}
```

Save this to `shell.nix`, then run:

```ShellSession
$ rustc --version
rustc 1.69.0-nightly (13471d3b2 2023-03-02)
```

To see that you are using nightly.

Oxalica's Rust overlay has more complete examples of `shell.nix` (and cross compilation) under its
[`examples` directory](https://github.com/oxalica/rust-overlay/tree/e53e8853aa7b0688bc270e9e6a681d22e01cf299/examples).

### Using Rust nightly in a derivation with `buildRustPackage` {#using-rust-nightly-in-a-derivation-with-buildrustpackage}

You can also use Rust nightly to build rust packages using `makeRustPlatform`.
The below snippet demonstrates invoking `buildRustPackage` with a Rust toolchain from oxalica's overlay:

```nix
with import <nixpkgs> {
  overlays = [
    (import (fetchTarball "https://github.com/oxalica/rust-overlay/archive/master.tar.gz"))
  ];
};
let
  rustPlatform = makeRustPlatform {
    cargo = rust-bin.selectLatestNightlyWith (toolchain: toolchain.default);
    rustc = rust-bin.selectLatestNightlyWith (toolchain: toolchain.default);
  };

in
rustPlatform.buildRustPackage (finalAttrs: {
  pname = "ripgrep";
  version = "14.1.1";

  src = fetchFromGitHub {
    owner = "BurntSushi";
    repo = "ripgrep";