nixpkgs/pkgs/development/compilers/rust/bootstrap.nix

{ stdenv, fetchurl, rust, callPackage, version, hashes }:

let
  platform = rust.toRustTarget stdenv.hostPlatform;

  src = fetchurl {
     url = "https://static.rust-lang.org/dist/rust-${version}-${platform}.tar.gz";
     sha256 = hashes.${platform} or (throw "missing bootstrap url for platform ${platform}");
  };

in callPackage ./binary.nix
  { inherit version src platform;
    versionType = "bootstrap";
  }