Strictly check the arguments to mkOption

And fix various instances of bad arguments.

lib/options.nix

@@ -11,17 +11,18 @@ with import ./strings.nix;
 rec {
 
   isOption = lib.isType "option";
-  mkOption = attrs: attrs // {
+  mkOption =
-    _type = "option";
+    { default ? null # Default value used when no definition is given in the configuration.
-    # name (this is the name of the attributem it is automatically generated by the traversal)
+    , defaultText ? null # Textual representation of the default, for in the manual.
-    # default (value used when no definition exists)
+    , example ? null # Example value used in the manual.
-    # example (documentation)
+    , description ? null # String describing the option.
-    # description (documentation)
+    , type ? null # Option type, providing type-checking and value merging.
-    # type (option type, provide a default merge function and ensure type correctness)
+    , apply ? null # Function that converts the option value to something else.
-    # merge (function used to merge definitions into one definition: [ /type/ ] -> /type/)
+    , internal ? null # Whether the option is for NixOS developers only.
-    # apply (convert the option value to ease the manipulation of the option result)
+    , visible ? null # Whether the option shows up in the manual.
-    # options (set of sub-options declarations & definitions)
+    , options ? null # Obsolete, used by types.optionSet.
-  };
+    } @ attrs:
+    attrs // { _type = "option"; };
 
   mkEnableOption = name: mkOption {
     default = false;

lib/types.nix

@@ -201,6 +201,9 @@ rec {
       name = /* builtins.trace "types.optionSet is deprecated; use types.submodule instead" */ "option set";
     };
 
+    # Augment the given type with an additional type check function.
+    addCheck = elemType: check: elemType // { check = x: elemType.check x && check x; };
+
   };
 
 }

nixos/modules/config/fonts/fontconfig.nix

@@ -9,6 +9,7 @@ with pkgs.lib;
     fonts = {
 
       enableFontConfig = mkOption { # !!! should be enableFontconfig
+        type = types.bool;
         default = true;
         description = ''
           If enabled, a Fontconfig configuration file will be built

nixos/modules/services/games/ghost-one.nix

@@ -21,7 +21,8 @@ in
 
       language = mkOption {
         default = "English";
-        check = lang: elem lang [ "English" "Spanish" "Russian" "Serbian" "Turkish" ];
+        type = types.addCheck types.str
+          (lang: elem lang [ "English" "Spanish" "Russian" "Serbian" "Turkish" ]);
         description = "The language of bot messages: English, Spanish, Russian, Serbian or Turkish.";
       };
 

nixos/modules/services/networking/bitlbee.nix

@@ -64,7 +64,7 @@ in
 
       authMode = mkOption {
         default = "Open";
-        check = authModeCheck;
+        type = types.addCheck types.str authModeCheck;
         description = ''
           The following authentication modes are available:
             Open -- Accept connections from anyone, use NickServ for user authentication.

nixos/modules/services/networking/minidlna.nix

@@ -32,7 +32,7 @@ in
     services.minidlna.mediaDirs = mkOption {
       type = types.listOf types.string;
       default = [];
-      examples = [ "/data/media" "V,/home/alice/video" ];
+      example = [ "/data/media" "V,/home/alice/video" ];
       description =
         ''
           Directories to be scanned for media files.  The prefixes

nixos/modules/services/networking/ssh/sshd.nix

@@ -102,7 +102,7 @@ in
 
       permitRootLogin = mkOption {
         default = "without-password";
-        check = permitRootLoginCheck;
+        type = types.addCheck types.str permitRootLoginCheck;
         description = ''
           Whether the root user can login using ssh. Valid values are
           <literal>yes</literal>, <literal>without-password</literal>,

nixos/modules/system/boot/systemd-unit-options.nix

@@ -2,7 +2,19 @@
 
 with pkgs.lib;
 
-rec {
+let
+
+  checkService = v:
+    let assertValueOneOf = name: values: attr:
+          let val = getAttr name attr;
+          in optional ( hasAttr name attr && !elem val values) "Systemd service field `${name}' cannot have value `${val}'.";
+        checkType = assertValueOneOf "Type" ["simple" "forking" "oneshot" "dbus" "notify" "idle"];
+        checkRestart = assertValueOneOf "Restart" ["no" "on-success" "on-failure" "on-abort" "always"];
+        errors = concatMap (c: c v) [checkType checkRestart];
+    in if errors == [] then true
+       else builtins.trace (concatStringsSep "\n" errors) false;
+
+in rec {
 
   unitOptions = {
 
@@ -147,23 +159,13 @@ rec {
         { StartLimitInterval = 10;
           RestartSec = 5;
         };
-      type = types.attrs;
+      type = types.addCheck types.attrs checkService;
       description = ''
         Each attribute in this set specifies an option in the
         <literal>[Service]</literal> section of the unit.  See
         <citerefentry><refentrytitle>systemd.service</refentrytitle>
         <manvolnum>5</manvolnum></citerefentry> for details.
       '';
-
-      check = v:
-        let assertValueOneOf = name: values: attr:
-              let val = getAttr name attr;
-              in optional ( hasAttr name attr && !elem val values) "${name} ${val} not known to systemd";
-            checkType = assertValueOneOf "Type" ["simple" "forking" "oneshot" "dbus" "notify" "idle"];
-            checkRestart = assertValueOneOf "Restart" ["no" "on-success" "on-failure" "on-abort" "always"];
-            errors = concatMap (c: c v) [checkType checkRestart];
-        in if errors == [] then true
-           else builtins.trace (concatStringsSep "\n" errors) false;
     };
 
     script = mkOption {

nixos/modules/system/upstart/upstart.nix

@@ -104,7 +104,7 @@ let
 
     name = mkOption {
       # !!! The type should ensure that this could be a filename.
-      type = types.string;
+      type = types.str;
       example = "sshd";
       description = ''
         Name of the Upstart job.
@@ -113,7 +113,7 @@ let
 
     startOn = mkOption {
       # !!! Re-enable this once we're on Upstart >= 0.6.
-      #type = types.string;
+      #type = types.str;
       default = "";
       description = ''
         The Upstart event that triggers this job to be started.
@@ -122,7 +122,7 @@ let
     };
 
     stopOn = mkOption {
-      type = types.string;
+      type = types.str;
       default = "starting shutdown";
       description = ''
         The Upstart event that triggers this job to be stopped.
@@ -130,7 +130,7 @@ let
     };
 
     postStart = mkOption {
-      type = types.string;
+      type = types.lines;
       default = "";
       description = ''
         Shell commands executed after the job is started (i.e. after
@@ -140,7 +140,7 @@ let
     };
 
     preStop = mkOption {
-      type = types.string;
+      type = types.lines;
       default = "";
       description = ''
         Shell commands executed before the job is stopped
@@ -150,7 +150,7 @@ let
     };
 
     postStop = mkOption {
-      type = types.string;
+      type = types.lines;
       default = "";
       description = ''
         Shell commands executed after the job has stopped
@@ -159,7 +159,7 @@ let
     };
 
     exec = mkOption {
-      type = types.string;
+      type = types.str;
       default = "";
       description = ''
         Command to start the job's main process.  If empty, the
@@ -189,7 +189,7 @@ let
     };
 
     daemonType = mkOption {
-      type = types.string;
+      type = types.str;
       default = "none";
       description = ''
         Determines how Upstart detects when a daemon should be
@@ -203,8 +203,7 @@ let
     };
 
     setuid = mkOption {
-      type = types.string;
+      type = types.addCheck types.str userExists;
-      check = userExists;
       default = "";
       description = ''
         Run the daemon as a different user.
@@ -212,8 +211,7 @@ let
     };
 
     setgid = mkOption {
-      type = types.string;
+      type = types.addCheck types.str groupExists;
-      check = groupExists;
       default = "";
       description = ''
         Run the daemon as a different group.