dbusbind: Check required args following :typescratch/dbusbind-type-tests

* src/dbusbind.c (xd_build_message): If no argument follows a type
specification, pass Qnil as OBJECT argument of
xd_append_arg_with_type_spec.
* test/automated/dbus-tests.el
(dbus-test04-create-message-parameters): Remove a temporary
comment.

2 files changed, 10 insertions, 2 deletions

diff --git a/src/dbusbind.c b/src/dbusbind.c
index 9747d88a5a9..63f46726455 100644
--- a/src/dbusbind.c
+++ b/src/dbusbind.c
@@ -1683,7 +1683,16 @@ xd_build_message (Lisp_Object caller, struct xd_message *xmessage,
     {
       if (EQ (args[count], QCdbus_type_type))
         {
-          xd_append_arg_with_type_spec (args[count+1], args[count+2], &iter);
+          /* At least one object must follow the `:type' symbol.  */
+          if (!(count+1 < nargs))
+            wrong_type_argument (intern ("D-Bus"), QCdbus_type_type);
+
+          /* It is possible that no argument follows a type
+             specification, when the type is an empty compound type.
+             Assume it as nil.  */
+          xd_append_arg_with_type_spec (args[count+1],
+                                        count+2 < nargs ? args[count+2] : Qnil,
+                                        &iter);
           count += 2;
         }
       else
diff --git a/test/automated/dbus-tests.el b/test/automated/dbus-tests.el
index 69afaa324f7..e989f73e68c 100644
--- a/test/automated/dbus-tests.el
+++ b/test/automated/dbus-tests.el
@@ -214,7 +214,6 @@ This includes initialization and closing the bus."
     (should (equal (plist-get message :args) '(((:array nil) nil))))
     (should (equal (plist-get message :signature) "au"))
     ;; Test explicit type specifications with `:type' keyword for empty array.
-    ;; DOES THIS WORK?
     (setq message (dbus--test-create-message-with-args
                    :type '(:array :uint32)))
     (should (equal (plist-get message :args) '(((:array nil) nil))))