3 files changed, 11 insertions, 5 deletions
diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index ce348ed3131..dfbda8d43e3 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -1401,7 +1401,7 @@ when printing the error message."
 (defun byte-compile-callargs-warn (form)
   (let* ((def (or (byte-compile-fdefinition (car form) nil)
 		  (byte-compile-fdefinition (car form) t)))
-	 (sig (byte-compile--function-signature def))
+         (sig (byte-compile--function-signature (or def (car form))))
 	 (ncall (length (cdr form))))
     ;; Check many or unevalled from subr-arity.
     (if (and (cdr-safe sig)
diff --git a/lisp/emacs-lisp/eieio-core.el b/lisp/emacs-lisp/eieio-core.el
index 31ee6c5bfd4..30445f9e645 100644
--- a/lisp/emacs-lisp/eieio-core.el
+++ b/lisp/emacs-lisp/eieio-core.el
@@ -117,9 +117,6 @@ Currently under control of this var:
 (defsubst eieio--object-class-tag (obj)
   (aref obj 0))
 
-(defsubst eieio--object-class (obj)
-  (eieio--object-class-tag obj))
-
 
 ;;; Important macros used internally in eieio.
 
@@ -132,6 +129,12 @@ Currently under control of this var:
       (or (cl--find-class class) class)
     class))
 
+(defsubst eieio--object-class (obj)
+  (let ((tag (eieio--object-class-tag obj)))
+    (if eieio-backward-compatibility
+        (eieio--class-object tag)
+      tag)))
+
 (defun class-p (x)
   "Return non-nil if X is a valid class vector.
 X can also be is a symbol."
@@ -163,7 +166,7 @@ Return nil if that option doesn't exist."
 (defun eieio-object-p (obj)
   "Return non-nil if OBJ is an EIEIO object."
   (and (recordp obj)
-       (eieio--class-p (eieio--object-class-tag obj))))
+       (eieio--class-p (eieio--object-class obj))))
 
 (define-obsolete-function-alias 'object-p 'eieio-object-p "25.1")
 
diff --git a/lisp/emacs-lisp/eieio.el b/lisp/emacs-lisp/eieio.el
index b6ec191e2ba..7ad44b6d26c 100644
--- a/lisp/emacs-lisp/eieio.el
+++ b/lisp/emacs-lisp/eieio.el
@@ -710,6 +710,9 @@ calls `initialize-instance' on that object."
     ;; Call the initialize method on the new object with the slots
     ;; that were passed down to us.
     (initialize-instance new-object slots)
+    (when eieio-backward-compatibility
+      ;; Use symbol as type descriptor, for backwards compatibility.
+      (aset new-object 0 class))
     ;; Return the created object.
     new-object))