Fix slot typecheck in eieio-persistent

* lisp/emacs-lisp/eieio-base.el (eieio-persistent-slot-type-is-class-p):
  An `or' form can specify multiple potential classes (or null) as
  valid types for a slot, but previously only the final element of the
  `or' was actually checked. Now returns all valid classes in the `or'
  form.
  (eieio-persistent-validate/fix-slot-value): Check if proposed value
  matches any of the valid classes.
* test/lisp/emacs-lisp/eieio-tests/eieio-test-persist.el
  (eieio-test-multiple-class-slot): Test this behavior.

lisp/emacs-lisp/eieio-base.el

@@ -31,6 +31,7 @@
 ;;; Code:
 
 (require 'eieio)
+(require 'seq)
 (eval-when-compile (require 'cl-lib))
 
 ;;; eieio-instance-inheritor
@@ -308,14 +309,6 @@ Second, any text properties will be stripped from strings."
 		       (= (length proposed-value) 1))
 		  nil)
 
-		  ;; We have a slot with a single object that can be
-		  ;; saved here.  Recurse and evaluate that
-		  ;; sub-object.
-		 ((and classtype (class-p classtype)
-		       (child-of-class-p (car proposed-value) classtype))
-		  (eieio-persistent-convert-list-to-object
-		   proposed-value))
-
 		 ;; List of object constructors.
 		 ((and (eq (car proposed-value) 'list)
 		       ;; 2nd item is a list.
@@ -346,6 +339,16 @@ Second, any text properties will be stripped from strings."
 			    objlist))
 		    ;; return the list of objects ... reversed.
 		    (nreverse objlist)))
+		 ;; We have a slot with a single object that can be
+		 ;; saved here.  Recurse and evaluate that
+		 ;; sub-object.
+		 ((and classtype
+                       (seq-some
+                        (lambda (elt)
+                          (child-of-class-p (car proposed-value) elt))
+                        classtype))
+		  (eieio-persistent-convert-list-to-object
+		   proposed-value))
 		 (t
 		  proposed-value))))
 
@@ -402,13 +405,9 @@ If no class is referenced there, then return nil."
 	       type))
 
 	((eq (car-safe type) 'or)
-	 ;; If type is a list, and is an or, it is possibly something
-	 ;; like (or null myclass), so check for that.
-	 (let ((ans nil))
-	   (dolist (subtype (cdr type))
-	     (setq ans (eieio-persistent-slot-type-is-class-p
-			subtype)))
-	   ans))
+	 ;; If type is a list, and is an `or', return all valid class
+	 ;; types within the `or' statement.
+	 (seq-filter #'eieio-persistent-slot-type-is-class-p (cdr type)))
 
 	(t
 	 ;; No match, not a class.

test/lisp/emacs-lisp/eieio-tests/eieio-test-persist.el

@@ -195,6 +195,28 @@ persistent class.")
     (persist-test-save-and-compare persist-woss)
     (delete-file (oref persist-woss file))))
 
+;; A slot that can contain one of two different classes, to exercise
+;; the `or' slot type.
+
+(defclass persistent-random-class ()
+  ())
+
+(defclass persistent-multiclass-slot (eieio-persistent)
+  ((slot1 :initarg :slot1
+          :type (or persistent-random-class null persist-not-persistent))
+   (slot2 :initarg :slot2
+          :type (or persist-not-persistent persist-random-class null))))
+
+(ert-deftest eieio-test-multiple-class-slot ()
+  (let ((persist
+         (persistent-multiclass-slot "random string"
+          :slot1 (persistent-random-class)
+          :slot2 (persist-not-persistent)
+          :file (concat default-directory "test-ps5.pt"))))
+    (unwind-protect
+        (persist-test-save-and-compare persist)
+     (ignore-errors (delete-file (oref persist file))))))
+
 ;;; Slot with a list of Objects
 ;;
 ;; A slot that contains another object that isn't persistent