org-element: Record origin buffer when parsing

* lisp/org-element.el (org-element-parse-buffer): Resolve all the
deferred values in the string.  If not, we might leave pointers to
killed buffer.
(org-element--parse-elements): Resolve deferred in objects.
(org-element--object-lex): Store :buffer property.
* lisp/org-macro.el (org-macro--find-date): Do not try to print
:buffer property.
* lisp/org-element.el (org-element--cache-persist-before-write):
(org-element--cache-persist-after-read): Clear and restore
non-printable buffer objects in :buffer property.

lisp/org-element.el

@@ -545,7 +545,8 @@ value of DATUM `:parent' property."
 
 (defconst org-element--cache-element-properties
   '(:cached
-    :org-element--cache-sync-key)
+    :org-element--cache-sync-key
+    :buffer)
   "List of element properties used internally by cache.")
 
 (defvar org-element--string-cache (obarray-make)
@@ -1157,7 +1158,8 @@ parser (e.g. `:end' and :END:).  Return value is a plist."
                   :post-blank (count-lines pos-before-blank end)
                   :post-affiliated begin
                   :path (buffer-file-name)
-                  :mode 'org-data)
+                  :mode 'org-data
+                  :buffer (current-buffer)))
            properties)))))
 
 (defun org-element-org-data-interpreter (_ contents)
@@ -4212,6 +4214,7 @@ element it has to parse."
 	    ;; Default element: Paragraph.
 	    (t (org-element-paragraph-parser limit affiliated)))))))
     (when result
+      (org-element-put-property result :buffer (current-buffer))
       (org-element-put-property result :mode mode)
       (org-element-put-property result :granularity granularity))
     result)))
@@ -4680,6 +4683,9 @@ Elements are accumulated into ACC."
 RESTRICTION is a list of object types, as symbols, that should be
 looked after.  This function assumes that the buffer is narrowed
 to an appropriate container (e.g., a paragraph)."
+  (let (result)
+    (setq
+     result
      (cond
       ((memq 'table-cell restriction) (org-element-table-cell-parser))
       ((memq 'citation-reference restriction)
@@ -4791,6 +4797,7 @@ to an appropriate container (e.g., a paragraph)."
 	         (limit (forward-char -1)
 		        (org-element-link-parser))	;radio link
 	         (t nil)))))))
+    (org-element-put-property result :buffer (current-buffer))))
 
 (defun org-element--parse-objects (beg end acc restriction &optional parent)
   "Parse objects between BEG and END and return recursive structure.
@@ -7049,10 +7056,15 @@ The element is: %S\n The real element is: %S\n Cache around :begin:\n%S\n%S\n%S"
               (org-with-wide-buffer
                (org-element--cache-sync (current-buffer) (point-max))
                ;; Cleanup cache request keys to avoid collisions during next
-               ;; Emacs session.
+               ;; Emacs session.  Cleanup known non-printable objects.
                (avl-tree-mapc
                 (lambda (el)
-                  (org-element-put-property el :org-element--cache-sync-key nil))
+                  (org-element-put-property el :org-element--cache-sync-key nil)
+                  (org-element-map el t
+                    (lambda (el2)
+                      (unless (eq 'plain-text (org-element-type el2))
+                        (org-element-put-property el2 :buffer nil)))
+                    nil nil nil 'with-affiliated 'no-undefer))
                 org-element--cache)
                nil)
             'forbid))
@@ -7079,6 +7091,15 @@ The element is: %S\n The real element is: %S\n Cache around :begin:\n%S\n%S\n%S"
     (with-current-buffer (get-file-buffer (plist-get associated :file))
       (when (and org-element-use-cache org-element-cache-persistent)
         (when (and (equal container '(elisp org-element--cache)) org-element--cache)
+          ;; Restore `:buffer' property.
+          (avl-tree-mapc
+           (lambda (el)
+             (org-element-map el t
+               (lambda (el2)
+                 (unless (eq 'plain-text (org-element-type el2))
+                   (org-element-put-property el2 :buffer (current-buffer))))
+               nil nil nil 'with-affiliated 'no-undefer))
+           org-element--cache)
           (setq-local org-element--cache-size (avl-tree-size org-element--cache)))
         (when (and (equal container '(elisp org-element--headline-cache)) org-element--headline-cache)
           (setq-local org-element--headline-cache-size (avl-tree-size org-element--headline-cache)))))))

lisp/org-macro.el

@@ -369,7 +369,10 @@ Return value as a string."
 	     (eq 'timestamp (org-element-type (car date))))
 	(format "(eval (if (org-string-nw-p $1) %s %S))"
 		(format "(org-format-timestamp '%S $1)"
-			(org-element-copy (car date)))
+			(org-element-put-property
+                         (org-element-copy (car date))
+                         ;; Remove non-printable.
+                         :buffer nil))
 		value)
       value)))