A Nix expression for nightly Rust versions

This is useful for working with the latest Rust nightly (or the nightly from a specific date) on NixOS. Notably, it uses Nix's builtins.fetchurl feature to avoid the need to specify source hashes manually. This feature is banned in nixpkgs, so this expression has to exist outside of it.

Essentially, this expression is convenient for development but unsuitable for official packaging.

Obtaining

You can fetch the whole repo and use it with something like:

{
  rustNightlyNixRepo = pkgs.fetchFromGitHub {
     owner = "solson";
     repo = "rust-nightly-nix";
     rev = "9e09d579431940367c1f6de9463944eef66de1d4";
     sha256 = "03zkjnzd13142yla52aqmgbbnmws7q8kn1l5nqaly22j31f125xy";
  };

  rustPackages = pkgs.callPackage rustNightlyNixRepo { };
}

Or you can just download default.nix file onto your system somewhere, and do:

{
  rustPackages = pkgs.callPackage /path/to/rust-nightly-nix { };
}

Note the the default.nix is a special name and thus you can use the path to be the directory containing it.

Invocation

default.nix is structure like a normal package in Nixpkgs in that it is a function from a attrset of package, suitable for calling with callPackage as show above. Unlike a normal package, however, it is a function not to a single derivation but two a set of functions. The functions it produces are as follows.

rustc

rustc is a function from a set of optional arguments to a derivation for the rust compiler. date determines which nightly to download (defaults to latest date where a nightly was successfully built). system is the system the compiler runs on (defaults to the system Nix is installed on). This is an LLVM- (and Rust-) style system name, not Nix-style. hash is the expect hash of the nightly download. The default here is somewhat complex, and marginally better than just an unchecked download. If no hash is provided, rust-nightly-nix will first download the hash from Mozilla (an unchecked download), then use the downloaded hash to verify the compiler download. That way, the compiler download is always verified with some hash.

As an example example,

{
  funs = callPackage /path/to/rust-nightly-nix { };

  rustcNightly = funs.rustc {
    date = "2016-06-09";
    hash = "1p0xkpfk66jq0iladqfrhqk1zc1jr9n2v2lqyf7jjbrmqx2ja65i";
  };
}

provides a hash to add some security to the build process.

cargo

cargo has the same type as rustc. Note that if one of a nightly Rust compiler build and nightly Cargo build fails and the other succeeds, the other is still published. So don't freak out if on some day half your downloads are failing.

rust-std

rust-std is used for prebuilt standard libraries. On "normal" platforms this is std and its dependencies but on more exotic platforms (e.g. small CPUs for embedded systems) it will contain less as std itself makes no sense. It has the same type as rustc. I (@Ericson2314) believe that the standard library for all all tier-1 platforms need to be built and tested for a nightly compiler to be released, so these will be released on the same days as rustc.

rustcWithSysroots

rustcWithSysroots bundles together a Rust compiler with some pre-built nightlies for easier cross-compiling.

takes rustc as an argument, plus an optional set of derivations to be put in scope for the build of rustc. This is particularly useful if you want to make rust-std avalable to rustc. For example you might invoke rustcWithSysroots in the following way in order to make different instances of rust-std avalable during the use of rustc.

{
  rustNightlyWithi686 = funs.rustcWithSysroots {
    rustc = rustcNightly;
    sysroots = builtins.map funs.rust-std [
      { } # native std, need for build.rs and proc macros
      { system = "x86_64-unknown-linux-gnu"; }
      { system = "i686-unknown-linux-gnu"; }
    ];
  };
}

rust

rust has the same type as rustc. It is the legacy/simple download, a combination of rustc, cargo, and rust-std for the build platform (not cross-compiling).

Exposing

This is the completely generic procedure for "installing" stuff with Nix or NixOS.

NixOS System-Wide Setup

You can install this globally by adding it as an override in the system's configuration at /etc/nixos/configuration.nix.

{
  nixpkgs.config.packageOverrides = pkgs: {
    rustNightly = pkgs.callPackage /path/to/rust-nightly-nix {};
  };
}

Nix User-Specific Setup

You can also set this up specifically for a single user by adding it to that user's nix configuration, located at $HOME/.nixpkgs/config.nix.

{
  packageOverrides = pkgs: {
    rustNightly = pkgs.callPackage /path/to/rust-nightly-nix {};
  };
}

Examples

Once you're set up, you should be able to run something like:

# To use a specific date:
nix-shell -p 'rustNightly.rust { date = "2016-01-01"; }'

# To use the latest:
nix-shell -p 'rustNightly.rust {}'

But there are more derivations in rustNightly than just rust. Check out the source for the full list. It's not too complicated.

You could also add any of these to your systemPackages or user environment (with nix-env).

Tip

I also added an alias to my packageOverrides:

{
  nixpkgs.config.packageOverrides = pkgs: rec {
    rustNightly = pkgs.callPackage /path/to/rust-nightly-nix {};
    rustLatest = rustNightly.rust {};
  };
}

So I can just run nix-shell -p rustLatest to work with my nightly projects.

Compile with musl

{
  rustPackages = pkgs.callPackage rustNightlyNixRepo { };

  cargoNightly = rustPackages.cargo { date = "2016-11-09"; };
  rustcNightly = rustPackages.rustc {};

  rustNightly = rustPackages.rustcWithSysroots {
    rustc = rustcNightly;
    sysroots = [
      (rustPackages.rust-std { })
      (rustPackages.rust-std { system = "x86_64-unknown-linux-musl"; })
    ];
  };
}

Now you can build cargo build --target x86_64-unknown-linux-musl :)

Note: of course the musl package needs to be installed too ;-)

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT) at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you shall be dual licensed as above, without any additional terms or conditions.