checkdoc: Don't warn for () in cl-defmacro args

Seen with, for example:

    (cl-defmacro foo (bar () &body baz) ...)

* lisp/emacs-lisp/checkdoc.el (checkdoc-this-string-valid-engine):
Improve support for `cl-defmacro' by ignoring "nil" in parameter list.

diff --git a/lisp/emacs-lisp/checkdoc.el b/lisp/emacs-lisp/checkdoc.el
index e918ec1eebdfa24a5448a6a06c39e40b709658b6..cf7b7c318f68d029803ce09ce3aa93162b88ae1e 100644 (file)
--- a/lisp/emacs-lisp/checkdoc.el
+++ b/lisp/emacs-lisp/checkdoc.el
@@ -1793,7 +1793,7 @@ function,command,variable,option or symbol." ms1))))))
                   (order (and (nth 3 fp) (car (nth 3 fp))))
                   (nocheck (append '("&optional" "&rest" "&key" "&aux"
                                       "&context" "&environment" "&whole"
-                                      "&body" "&allow-other-keys")
+                                      "&body" "&allow-other-keys" "nil")
                                     (nth 3 fp)))
                   (inopts nil))
               (while (and args found (> found last-pos))