lib/options: Throw error for options without a type

Makes all options rendered in the manual throw an error if they don't
have a type specified.

This is a follow-up to #76184

Co-Authored-By: Silvan Mosberger <contact@infinisil.com>

3 files changed, 17 insertions, 7 deletions

diff --git a/nixos/doc/manual/development/option-declarations.section.md b/nixos/doc/manual/development/option-declarations.section.md
index fff06e1ea5b..cb5043b528f 100644
--- a/nixos/doc/manual/development/option-declarations.section.md
+++ b/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`
 
diff --git a/nixos/doc/manual/from_md/development/option-declarations.section.xml b/nixos/doc/manual/from_md/development/option-declarations.section.xml
index 0eeffae628e..c7b62192158 100644
--- a/nixos/doc/manual/from_md/development/option-declarations.section.xml
+++ b/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>
diff --git a/nixos/lib/make-options-doc/mergeJSON.py b/nixos/lib/make-options-doc/mergeJSON.py
index 029787a3158..8e2ea322dc8 100644
--- a/nixos/lib/make-options-doc/mergeJSON.py
+++ b/nixos/lib/make-options-doc/mergeJSON.py
@@ -66,14 +66,21 @@ for (k, v) in overrides.items():
         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" +