Renege on anonymous &rest (bug#50268, bug#50720)

Allowing &rest without a variable name following turned out not to be
very useful, and it never worked properly.  Disallow it.

* lisp/emacs-lisp/bytecomp.el (byte-compile-check-lambda-list):
* src/eval.c (funcall_lambda):
Signal error for &rest without variable name.
* doc/lispref/functions.texi (Argument List): Adjust manual.
* etc/NEWS (file): Announce.
* test/src/eval-tests.el (eval-tests--bugs-24912-and-24913):
Extend test, also checking with and without lexical binding.
(eval-tests-accept-empty-optional-rest): Reduce to...
(eval-tests-accept-empty-optional): ...this, again checking
with and without lexical binding.

1 files changed, 33 insertions, 24 deletions

diff --git a/test/src/eval-tests.el b/test/src/eval-tests.el
index b2b7dfefda5..3c3e7033419 100644
--- a/test/src/eval-tests.el
+++ b/test/src/eval-tests.el
@@ -39,31 +39,40 @@
 (ert-deftest eval-tests--bugs-24912-and-24913 ()
   "Check that Emacs doesn't accept weird argument lists.
 Bug#24912 and Bug#24913."
-  (dolist (args '((&rest &optional)
-                  (&rest a &optional) (&rest &optional a)
-                  (&optional &optional) (&optional &optional a)
-                  (&optional a &optional b)
-                  (&rest &rest) (&rest &rest a)
-                  (&rest a &rest b)))
-    (should-error (eval `(funcall (lambda ,args)) t) :type 'invalid-function)
-    (should-error (byte-compile-check-lambda-list args))
-    (let ((byte-compile-debug t))
-      (ert-info ((format "bytecomp: args = %S" args))
-       (should-error (eval `(byte-compile (lambda ,args)) t))))))
-
-(ert-deftest eval-tests-accept-empty-optional-rest ()
-  "Check that Emacs accepts empty &optional and &rest arglists.
+  (dolist (lb '(t false))
+    (ert-info ((prin1-to-string lb) :prefix "lexical-binding: ")
+      (let ((lexical-binding lb))
+        (dolist (args '((&rest &optional)
+                        (&rest a &optional) (&rest &optional a)
+                        (&optional &optional) (&optional &optional a)
+                        (&optional a &optional b)
+                        (&rest &rest) (&rest &rest a)
+                        (&rest a &rest b)
+                        (&rest) (&optional &rest)
+                        ))
+          (ert-info ((prin1-to-string args) :prefix "args: ")
+            (should-error
+             (eval `(funcall (lambda ,args)) lb) :type 'invalid-function)
+            (should-error (byte-compile-check-lambda-list args))
+            (let ((byte-compile-debug t))
+              (should-error (eval `(byte-compile (lambda ,args)) lb)))))))))
+
+(ert-deftest eval-tests-accept-empty-optional ()
+  "Check that Emacs accepts empty &optional arglists.
 Bug#24912."
-  (dolist (args '((&optional) (&rest) (&optional &rest)
-                  (&optional &rest a) (&optional a &rest)))
-    (let ((fun `(lambda ,args 'ok)))
-      (ert-info ("eval")
-        (should (eq (funcall (eval fun t)) 'ok)))
-      (ert-info ("byte comp check")
-        (byte-compile-check-lambda-list args))
-      (ert-info ("bytecomp")
-        (let ((byte-compile-debug t))
-          (should (eq (funcall (byte-compile fun)) 'ok)))))))
+  (dolist (lb '(t false))
+    (ert-info ((prin1-to-string lb) :prefix "lexical-binding: ")
+      (let ((lexical-binding lb))
+        (dolist (args '((&optional) (&optional &rest a)))
+          (ert-info ((prin1-to-string args) :prefix "args: ")
+            (let ((fun `(lambda ,args 'ok)))
+              (ert-info ("eval")
+                (should (eq (funcall (eval fun lb)) 'ok)))
+              (ert-info ("byte comp check")
+                (byte-compile-check-lambda-list args))
+              (ert-info ("bytecomp")
+                (let ((byte-compile-debug t))
+                  (should (eq (funcall (byte-compile fun)) 'ok)))))))))))
 
 
 (dolist (form '(let let*))