Add a sanity check to apropos-documentation-internal

* lisp/apropos.el (apropos-documentation-internal): Add a
sanity check to be less fragile in the presence of invalid
data (bug#16725).

1 files changed, 17 insertions, 13 deletions

diff --git a/lisp/apropos.el b/lisp/apropos.el
index eb145bdc571..6009f30f7a8 100644
--- a/lisp/apropos.el
+++ b/lisp/apropos.el
@@ -867,19 +867,23 @@ Returns list of symbols and documentation found."
               symbol)))))
 
 (defun apropos-documentation-internal (doc)
-  (if (consp doc)
-      (apropos-documentation-check-elc-file (car doc))
-    (if (and doc
-             (string-match apropos-all-words-regexp doc)
-             (apropos-true-hit-doc doc))
-        (when apropos-match-face
-          (setq doc (substitute-command-keys (copy-sequence doc)))
-          (if (or (string-match apropos-pattern-quoted doc)
-                  (string-match apropos-all-words-regexp doc))
-              (put-text-property (match-beginning 0)
-                                 (match-end 0)
-                                 'face apropos-match-face doc))
-          doc))))
+  (cond
+   ((consp doc)
+    (apropos-documentation-check-elc-file (car doc)))
+   ((and doc
+         ;; Sanity check in case bad data has snuck into the
+         ;; documentation slot.
+         (stringp doc)
+         (string-match apropos-all-words-regexp doc)
+         (apropos-true-hit-doc doc))
+    (when apropos-match-face
+      (setq doc (substitute-command-keys (copy-sequence doc)))
+      (if (or (string-match apropos-pattern-quoted doc)
+              (string-match apropos-all-words-regexp doc))
+          (put-text-property (match-beginning 0)
+                             (match-end 0)
+                             'face apropos-match-face doc))
+      doc))))
 
 (defun apropos-format-plist (pl sep &optional compare)
   (setq pl (symbol-plist pl))