Throw an error for options without a type

lib/options.nix

@@ -231,7 +231,7 @@ rec {
             then true
             else opt.visible or true;
           readOnly = opt.readOnly or false;
-          type = opt.type.description or null;
+          type = opt.type.description or "unspecified";
         }
         // optionalAttrs (opt ? example) { example = scrubOptionValue opt.example; }
         // optionalAttrs (opt ? default) { default = scrubOptionValue opt.default; }

nixos/doc/manual/development/option-declarations.section.md

@@ -27,9 +27,10 @@ The function `mkOption` accepts the following arguments.
 
 `type`
 
-:   The type of the option (see [](#sec-option-types)). It may be
-    omitted, but that's not advisable since it may lead to errors that
-    are hard to diagnose.
+:   The type of the option (see [](#sec-option-types)). This
+    argument is mandatory for nixpkgs modules. Setting this is highly
+    recommended for the sake of documentation and type checking. In case it is
+    not set, a fallback type with unspecified behavior is used.
 
 `default`
 

nixos/doc/manual/from_md/development/option-declarations.section.xml

@@ -38,9 +38,11 @@ options = {
       <listitem>
         <para>
           The type of the option (see
-          <xref linkend="sec-option-types" />). It may be omitted, but
-          that’s not advisable since it may lead to errors that are hard
-          to diagnose.
+          <xref linkend="sec-option-types" />). This argument is
+          mandatory for nixpkgs modules. Setting this is highly
+          recommended for the sake of documentation and type checking.
+          In case it is not set, a fallback type with unspecified
+          behavior is used.
         </para>
       </listitem>
     </varlistentry>

nixos/lib/make-options-doc/mergeJSON.py

@@ -66,14 +66,21 @@ def unpivot(options: Dict[Key, Option]) -> Dict[str, JSON]:
         elif ov is not None or cur.get(ok, None) is None:
             cur[ok] = ov
 
+severity = "error" if warningsAreErrors else "warning"
+
 # check that every option has a description
 hasWarnings = False
 for (k, v) in options.items():
     if v.value.get('description', None) is None:
-        severity = "error" if warningsAreErrors else "warning"
         hasWarnings = True
         print(f"\x1b[1;31m{severity}: option {v.name} has no description\x1b[0m", file=sys.stderr)
         v.value['description'] = "This option has no description."
+    if v.value.get('type', "unspecified") == "unspecified":
+        hasWarnings = True
+        print(
+            f"\x1b[1;31m{severity}: option {v.name} has no type. Please specify a valid type, see " +
+            "https://nixos.org/manual/nixos/stable/index.html#sec-option-types\x1b[0m", file=sys.stderr)
+
 if hasWarnings and warningsAreErrors:
     print(
         "\x1b[1;31m" +

nixos/modules/services/networking/nsd.nix

@@ -194,19 +194,8 @@ let
                        zone.children
       );
 
-  # fighting infinite recursion
-  zoneOptions = zoneOptionsRaw // childConfig zoneOptions1 true;
-  zoneOptions1 = zoneOptionsRaw // childConfig zoneOptions2 false;
-  zoneOptions2 = zoneOptionsRaw // childConfig zoneOptions3 false;
-  zoneOptions3 = zoneOptionsRaw // childConfig zoneOptions4 false;
-  zoneOptions4 = zoneOptionsRaw // childConfig zoneOptions5 false;
-  zoneOptions5 = zoneOptionsRaw // childConfig zoneOptions6 false;
-  zoneOptions6 = zoneOptionsRaw // childConfig null         false;
-
-  childConfig = x: v: { options.children = { type = types.attrsOf x; visible = v; }; };
-
   # options are ordered alphanumerically
-  zoneOptionsRaw = types.submodule {
+  zoneOptions = types.submodule {
     options = {
 
       allowAXFRFallback = mkOption {
@@ -246,6 +235,13 @@ let
       };
 
       children = mkOption {
+        # TODO: This relies on the fact that `types.anything` doesn't set any
+        # values of its own to any defaults, because in the above zoneConfigs',
+        # values from children override ones from parents, but only if the
+        # attributes are defined. Because of this, we can't replace the element
+        # type here with `zoneConfigs`, since that would set all the attributes
+        # to default values, breaking the parent inheriting function.
+        type = types.attrsOf types.anything;
         default = {};
         description = ''
           Children zones inherit all options of their parents. Attributes

nixos/modules/services/networking/unbound.nix

@@ -62,6 +62,7 @@ in {
       };
 
       stateDir = mkOption {
+        type = types.path;
         default = "/var/lib/unbound";
         description = "Directory holding all state for unbound to run.";
       };

nixos/modules/services/networking/vsftpd.nix

@@ -153,6 +153,7 @@ in
 
       userlist = mkOption {
         default = [];
+        type = types.listOf types.str;
         description = "See <option>userlistFile</option>.";
       };
 

nixos/modules/services/x11/display-managers/default.nix

@@ -219,6 +219,24 @@ in
 
       session = mkOption {
         default = [];
+        type = with types; listOf (submodule ({ ... }: {
+          options = {
+            manage = mkOption {
+              description = "Whether this is a desktop or a window manager";
+              type = enum [ "desktop" "window" ];
+            };
+
+            name = mkOption {
+              description = "Name of this session";
+              type = str;
+            };
+
+            start = mkOption {
+              description = "Commands to run to start this session";
+              type = lines;
+            };
+          };
+        }));
         example = literalExpression
           ''
             [ { manage = "desktop";

nixos/modules/system/boot/kernel.nix

@@ -36,7 +36,7 @@ in
 
     boot.kernelPackages = mkOption {
       default = pkgs.linuxPackages;
-      type = types.unspecified // { merge = mergeEqualOption; };
+      type = types.raw;
       apply = kernelPackages: kernelPackages.extend (self: super: {
         kernel = super.kernel.override (originalArgs: {
           inherit randstructSeed;

nixos/modules/system/boot/stage-1.nix

@@ -581,7 +581,7 @@ in
         else "gzip"
       );
       defaultText = literalDocBook "<literal>zstd</literal> if the kernel supports it (5.9+), <literal>gzip</literal> if not";
-      type = types.unspecified; # We don't have a function type...
+      type = types.either types.str (types.functionTo types.str);
       description = ''
         The compressor to use on the initrd image. May be any of: