···

       
1
       
 
       
let

     

       
2
       
-
       
  requiredVersion = import ./lib/minver.nix;

     

       
3
       
 
       
in

     

       
4
       
 
       


     

       
5
       
-
       
if !builtins ? nixVersion || builtins.compareVersions requiredVersion builtins.nixVersion == 1 then

     

       
6
       
 
       


     

       
7
       
 
       
  abort ''

     

       
8
       
 
       


     

       
9
       
-
       
    This version of Nixpkgs requires Nix >= ${requiredVersion} but it is being

     

       
10
       
-
       
    evaluated with Nix ${builtins.nixVersion or "(too old to know)"}, please upgrade:

     

       
0
       
 
       

     

       
0
       
 
       

     

       
11
       
 
       


     

       
12
       
 
       
    - If you are running NixOS, `nixos-rebuild' can be used to upgrade your system.

     

       
13
       
 
       


     

···

       
1
       
 
       
let

     

       
2
       
+
       
  missingFeatures = map ({ description, ... }: description) (import ./lib/minfeatures.nix).missing;

     

       
3
       
 
       
in

     

       
4
       
 
       


     

       
5
       
+
       
if missingFeatures != [ ] then

     

       
6
       
 
       


     

       
7
       
 
       
  abort ''

     

       
8
       
 
       


     

       
9
       
+
       
    This version of Nixpkgs requires an implementation of Nix with the following features:

     

       
10
       
+
       
    - ${builtins.concatStringsSep "\n- " missingFeatures}

     

       
11
       
+
       


     

       
12
       
+
       
    Your are evaluating with Nix ${builtins.nixVersion or "(too old to know)"}, please upgrade:

     

       
13
       
 
       


     

       
14
       
 
       
    - If you are running NixOS, `nixos-rebuild' can be used to upgrade your system.

     

       
15
       
 
       


     

···

       
19
       
 
       
  Example: `lib.take` is an alias for `lib.lists.take`.

     

       
20
       
 
       


     

       
21
       
 
       
Most files in this directory are definitions of sub-libraries, but there are a few others:

     

       
22
       
-
       
- [`minver.nix`](minver.nix): A string of the minimum version of Nix that is required to evaluate Nixpkgs.

     

       
23
       
 
       
- [`tests`](tests): Tests, see [Running tests](#running-tests)

     

       
24
       
 
       
  - [`release.nix`](tests/release.nix): A derivation aggregating all tests

     

       
25
       
 
       
  - [`misc.nix`](tests/misc.nix): Evaluation unit tests for most sub-libraries

     

···

       
19
       
 
       
  Example: `lib.take` is an alias for `lib.lists.take`.

     

       
20
       
 
       


     

       
21
       
 
       
Most files in this directory are definitions of sub-libraries, but there are a few others:

     

       
22
       
+
       
- [`minfeatures.nix`](minfeatures.nix): A list of conditions for the used Nix version to match that are required to evaluate Nixpkgs.

     

       
23
       
 
       
- [`tests`](tests): Tests, see [Running tests](#running-tests)

     

       
24
       
 
       
  - [`release.nix`](tests/release.nix): A derivation aggregating all tests

     

       
25
       
 
       
  - [`misc.nix`](tests/misc.nix): Evaluation unit tests for most sub-libraries

     

···

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

···

       
1
       
+
       
let

     

       
2
       
+
       
  features = [

     

       
3
       
+
       
    {

     

       
4
       
+
       
      description = "the `nixVersion` builtin";

     

       
5
       
+
       
      condition = builtins ? nixVersion;

     

       
6
       
+
       
    }

     

       
7
       
+
       
    {

     

       
8
       
+
       
      description = "`builtins.nixVersion` reports at least 2.18";

     

       
9
       
+
       
      condition = builtins ? nixVersion && builtins.compareVersions "2.18" builtins.nixVersion != 1;

     

       
10
       
+
       
    }

     

       
11
       
+
       
  ];

     

       
12
       
+
       


     

       
13
       
+
       
  evaluated = builtins.partition ({ condition, ... }: condition) features;

     

       
14
       
+
       
in

     

       
15
       
+
       
{

     

       
16
       
+
       
  all = features;

     

       
17
       
+
       
  supported = evaluated.right;

     

       
18
       
+
       
  missing = evaluated.wrong;

     

       
19
       
+
       
}

     

···

       
1
       
-
       
# Expose the minimum required version for evaluating Nixpkgs

     

       
2
       
-
       
"2.18"

     

···

       
0
       
 
       

     

       
0