Fix incorrect cloning of eieio-instance-inheritor objects (Bug#34840)

* lisp/emacs-lisp/eieio-base.el (clone): Unbound slots of
  eieio-instance-inheritor objects as documented in the docs string
  and implemented in the original eieio implementation.

2 files changed, 51 insertions, 2 deletions

diff --git a/lisp/emacs-lisp/eieio-base.el b/lisp/emacs-lisp/eieio-base.el
index 3aeda92db12..62f4c82026e 100644
--- a/lisp/emacs-lisp/eieio-base.el
+++ b/lisp/emacs-lisp/eieio-base.el
@@ -64,10 +64,18 @@ SLOT-NAME is the offending slot.  FN is the function signaling the error."
     ;; Throw the regular signal.
     (cl-call-next-method)))
 
-(cl-defmethod clone ((obj eieio-instance-inheritor) &rest _params)
+(cl-defmethod clone ((obj eieio-instance-inheritor) &rest params)
   "Clone OBJ, initializing `:parent' to OBJ.
 All slots are unbound, except those initialized with PARAMS."
-  (let ((nobj (cl-call-next-method)))
+  ;; call next method without params as we makeunbound slots anyhow
+  (let ((nobj  (if (stringp (car params))
+                   (cl-call-next-method obj (pop params))
+                 (cl-call-next-method obj))))
+    (dolist (descriptor (eieio-class-slots (class-of nobj)))
+      (let ((slot (eieio-slot-descriptor-name descriptor)))
+        (slot-makeunbound nobj slot)))
+    (when params
+      (shared-initialize nobj params))
     (oset nobj parent-instance obj)
     nobj))
 
diff --git a/test/lisp/emacs-lisp/eieio-tests/eieio-tests.el b/test/lisp/emacs-lisp/eieio-tests/eieio-tests.el
index 0c7b6b71c31..1084c99dd5c 100644
--- a/test/lisp/emacs-lisp/eieio-tests/eieio-tests.el
+++ b/test/lisp/emacs-lisp/eieio-tests/eieio-tests.el
@@ -696,6 +696,17 @@ Do not override for `prot-2'."
   (setq eitest-II3 (clone eitest-II2 "eitest-II3 Test."))
   (oset eitest-II3 slot3 'penguin)
 
+  ;; Test that slots are non-initialized slots are unbounded
+  (oref eitest-II2 slot1)
+  (should (slot-boundp eitest-II2 'slot1))
+  (should-not (slot-boundp eitest-II2 'slot2))
+  (should-not (slot-boundp eitest-II2 'slot3))
+  (should-not (slot-boundp eitest-II3 'slot2))
+  (should-not (slot-boundp eitest-II3 'slot1))
+  (should-not (slot-boundp eitest-II3 'slot2))
+  (should (eieio-instance-inheritor-slot-boundp eitest-II3 'slot2))
+  (should (slot-boundp eitest-II3 'slot3))
+
   ;; Test level 1 inheritance
   (should (eq (oref eitest-II3 slot1) 'moose))
   ;; Test level 2 inheritance
@@ -913,6 +924,36 @@ Subclasses to override slot attributes.")
     (should (string= "aa-1" (oref D object-name)))
     (should (string= "aa-2" (oref E object-name)))))
 
+(defclass TII (eieio-instance-inheritor)
+  ((a :initform 1 :initarg :a)
+   (b :initarg :b)
+   (c :initarg :c))
+  "Instance Inheritor test class.")
+
+(ert-deftest eieio-test-39-clone-instance-inheritor-with-args ()
+  (let* ((A (TII))
+         (B (clone A :b "bb"))
+         (C (clone B :a "aa")))
+
+    (should (string= "aa" (oref C :a)))
+    (should (string= "bb" (oref C :b)))
+
+    (should (slot-boundp A :a))
+    (should-not (slot-boundp A :b))
+    (should-not (slot-boundp A :c))
+
+    (should-not (slot-boundp B :a))
+    (should (slot-boundp B :b))
+    (should-not (slot-boundp A :c))
+
+    (should (slot-boundp C :a))
+    (should-not (slot-boundp C :b))
+    (should-not (slot-boundp C :c))
+
+    (should (eieio-instance-inheritor-slot-boundp C :a))
+    (should (eieio-instance-inheritor-slot-boundp C :b))
+    (should-not (eieio-instance-inheritor-slot-boundp C :c))))
+
 
 (provide 'eieio-tests)