lib/minfeatures: init from minver.nix (#433057)

let

  requiredVersion = import ./lib/minver.nix;

  missingFeatures = map ({ description, ... }: description) (import ./lib/minfeatures.nix).missing;

in

if !builtins ? nixVersion || builtins.compareVersions requiredVersion builtins.nixVersion == 1 then

if missingFeatures != [ ] then

  abort ''

    This version of Nixpkgs requires Nix >= ${requiredVersion} but it is being

    evaluated with Nix ${builtins.nixVersion or "(too old to know)"}, please upgrade:

    This version of Nixpkgs requires an implementation of Nix with the following features:

    - ${builtins.concatStringsSep "\n- " missingFeatures}

    Your are evaluating with Nix ${builtins.nixVersion or "(too old to know)"}, please upgrade:

    - If you are running NixOS, `nixos-rebuild' can be used to upgrade your system.

  Example: `lib.take` is an alias for `lib.lists.take`.

Most files in this directory are definitions of sub-libraries, but there are a few others:

- [`minver.nix`](minver.nix): A string of the minimum version of Nix that is required to evaluate Nixpkgs.

- [`minfeatures.nix`](minfeatures.nix): A list of conditions for the used Nix version to match that are required to evaluate Nixpkgs.

- [`tests`](tests): Tests, see [Running tests](#running-tests)

  - [`release.nix`](tests/release.nix): A derivation aggregating all tests

  - [`misc.nix`](tests/misc.nix): Evaluation unit tests for most sub-libraries

let

  features = [

    {

      description = "the `nixVersion` builtin";

      condition = builtins ? nixVersion;

    }

    {

      description = "`builtins.nixVersion` reports at least 2.18";

      condition = builtins ? nixVersion && builtins.compareVersions "2.18" builtins.nixVersion != 1;

    }

  ];

  evaluated = builtins.partition ({ condition, ... }: condition) features;

in

{

  all = features;

  supported = evaluated.right;

  missing = evaluated.wrong;

}

# Expose the minimum required version for evaluating Nixpkgs

"2.18"