ci: bump cachix/install-nix-action

.github/workflows/build.yml

@@ -14,7 +14,7 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - uses: cachix/install-nix-action@v19
+      - uses: cachix/install-nix-action@v20
       - name: Check ${{ matrix.check }}
         # Depends on nixos/nix#7759 to simply `nix flake check`
         run: nix run .#checks.$(nix eval --raw --impure --expr "builtins.currentSystem").${{ matrix.check }}
@@ -45,7 +45,7 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v3
     - name: Install nix
-      uses: cachix/install-nix-action@v19
+      uses: cachix/install-nix-action@v20
     - name: Show nixpkgs version
       run: nix eval --impure --expr '(import ./flake-compat.nix { src = ./.; }).lib.version'
     - name: Setup cachix

.github/workflows/update.yml

@@ -12,7 +12,7 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - uses: cachix/install-nix-action@v19
+      - uses: cachix/install-nix-action@v20
         with:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}

callUnitRoot.nix

@@ -0,0 +1,10 @@
+{ pkgs, lib ? pkgs.lib, unitDir ? "unit", packageFun ? "package.nix", root ? "${./pkgs}/${unitDir}" }:
+let
+  shards = lib.attrNames (builtins.readDir root);
+  namesForShard = shard: lib.mapAttrs'
+    (name: _: { inherit name; value = "${root}/${shard}/${name}"; })
+    (builtins.readDir "${root}/${shard}");
+  namesToPath = lib.foldl' lib.recursiveUpdate { } (map namesForShard shards);
+  units = lib.mapAttrs (_: path: pkgs.callPackage "${path}/${packageFun}" { }) namesToPath;
+in
+units

default.nix

@@ -9,9 +9,9 @@
 { pkgs ? import <nixpkgs> { } }:
 
 import ./pkgs/top-level/all-packages.nix { inherit pkgs; }
-  // {
+// {
   # The `lib`, `modules`, and `overlay` names are special
   lib = import ./lib { inherit pkgs; }; # functions
   modules = import ./modules; # NixOS modules
   overlays = import ./overlays; # nixpkgs overlays
-}
+} // import ./callUnitRoot.nix { inherit pkgs; }

flake.nix

@@ -20,23 +20,11 @@
           # Unstable names are variables.
           packages =
             let
-              unitDir = "unit";
-              packageFun = "package.nix";
 
-              callUnitRoot = root:
-                let
-                  shards = lib.attrNames (builtins.readDir root);
-                  namesForShard = shard: lib.mapAttrs'
-                    (name: _: { inherit name; value = "${root}/${shard}/${name}"; })
-                    (builtins.readDir "${root}/${shard}");
-                  namesToPath = lib.foldl' lib.recursiveUpdate { } (map namesForShard shards);
-                  units = lib.mapAttrs (_: path: pkgs.callPackage "${path}/${packageFun}" { }) namesToPath;
-                in
-                units;
               legacyPackages = import ./pkgs/top-level/all-packages.nix { inherit pkgs; };
               onlyAvailable = lib.filterAttrs (_: drv: builtins.elem system (drv.meta.platforms or [ ]));
             in
-            onlyAvailable (legacyPackages // callUnitRoot "${./pkgs}/${unitDir}");
+            onlyAvailable (legacyPackages // import ./callUnitRoot.nix { inherit pkgs; });
 
           checks = {
             nixpkgs-fmt = pkgs.writeShellScriptBin "nixpkgs-fmt-check" ''