push sheeet

nixos/modules/misc/assertions.nix

@@ -0,0 +1,38 @@
+{ lib, ... }:
+{
+
+  options = {
+
+    assertions = lib.mkOption {
+      type = lib.types.listOf lib.types.unspecified;
+      internal = true;
+      default = [ ];
+      example = [
+        {
+          assertion = false;
+          message = "you can't enable this for that reason";
+        }
+      ];
+      description = ''
+        This option allows modules to express conditions that must
+        hold for the evaluation of the system configuration to
+        succeed, along with associated error messages for the user.
+      '';
+    };
+
+    warnings = lib.mkOption {
+      internal = true;
+      default = [ ];
+      type = lib.types.listOf lib.types.str;
+      example = [ "The `foo' service is deprecated and will go away soon!" ];
+      description = ''
+        This option allows modules to show warnings to users during
+        the evaluation of the system configuration.
+      '';
+    };
+
+  };
+  # impl of assertions is in
+  # - <nixpkgs/nixos/modules/system/activation/top-level.nix>
+  # - <nixpkgs/nixos/modules/system/service/portable/lib.nix>
+}