Mention new strictness for &optional, &rest in arglists (Bug#29165)

* etc/NEWS: Explain that '&optional' not followed by a variable is now
an error.
* lisp/emacs-lisp/cl-macs.el (cl--transform-lambda, cl--do-&aux)
(cl--do-arglist): Also reject '&optional', '&rest', or '&aux' not
followed by a variable for consistency.
* test/lisp/emacs-lisp/cl-macs-tests.el (cl-macs-bad-arglist): New
test.

1 files changed, 27 insertions, 11 deletions

diff --git a/lisp/emacs-lisp/cl-macs.el b/lisp/emacs-lisp/cl-macs.el
index 5535100d4ae..6aed060cb50 100644
--- a/lisp/emacs-lisp/cl-macs.el
+++ b/lisp/emacs-lisp/cl-macs.el
@@ -281,8 +281,13 @@ FORM is of the form (ARGS . BODY)."
                   (or (not optional)
                       ;; Optional args whose default is nil are simple.
                       (null (nth 1 (assq (car args) (cdr cl--bind-defs)))))
-                  (not (and (eq (car args) '&optional) (setq optional t)
-                            (car cl--bind-defs))))
+                  (not (and (eq (car args) '&optional)
+                            (progn
+                              (when (memq (cadr args)
+                                          '(nil &rest &body &key &aux))
+                                (error "Variable missing after &optional"))
+                              (setq optional t)
+                              (car cl--bind-defs)))))
         (push (pop args) simple-args))
       (when optional
         (if args (push '&optional args))
@@ -534,14 +539,17 @@ its argument list allows full Common Lisp conventions."
               arglist))))
 
 (defun cl--do-&aux (args)
-  (while (and (eq (car args) '&aux) (pop args))
-    (while (and args (not (memq (car args) cl--lambda-list-keywords)))
-      (if (consp (car args))
-          (if (and cl--bind-enquote (cl-cadar args))
-              (cl--do-arglist (caar args)
-                              `',(cadr (pop args)))
-            (cl--do-arglist (caar args) (cadr (pop args))))
-        (cl--do-arglist (pop args) nil))))
+  (when (eq (car args) '&aux)
+    (pop args)
+    (when (null args)
+      (error "Variable missing after &aux")))
+  (while (and args (not (memq (car args) cl--lambda-list-keywords)))
+    (if (consp (car args))
+        (if (and cl--bind-enquote (cl-cadar args))
+            (cl--do-arglist (caar args)
+                            `',(cadr (pop args)))
+          (cl--do-arglist (caar args) (cadr (pop args))))
+      (cl--do-arglist (pop args) nil)))
   (if args (error "Malformed argument list ends with: %S" args)))
 
 (defun cl--do-arglist (args expr &optional num)   ; uses cl--bind-*
@@ -558,6 +566,9 @@ its argument list allows full Common Lisp conventions."
 	  (keys nil)
 	  (laterarg nil) (exactarg nil) minarg)
       (or num (setq num 0))
+      (when (and restarg (or (null (cdr restarg))
+                             (memq (cadr restarg) cl--lambda-list-keywords)))
+        (error "Variable missing after &rest"))
       (setq restarg (if (listp (cadr restarg))
                         (make-symbol "--cl-rest--")
                       (cadr restarg)))
@@ -609,7 +620,12 @@ its argument list allows full Common Lisp conventions."
                                       `',cl--bind-block)
                                 (+ ,num (length ,restarg)))))
                   cl--bind-forms)))
-      (while (and (eq (car args) '&key) (pop args))
+      (while (eq (car args) '&key)
+        (pop args)
+        (when (or (null args) (memq (car args) cl--lambda-list-keywords))
+          (error "Missing variable after &key"))
+        (when keys
+          (error "Multiple occurrences of &key"))
 	(while (and args (not (memq (car args) cl--lambda-list-keywords)))
 	  (let ((arg (pop args)))
 	    (or (consp arg) (setq arg (list arg)))