2 files changed, 19 insertions, 10 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 96410c6c929..fa79352e7a2 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2013-12-18  Shigeru Fukaya <shigeru.fukaya@gmail.com>
+
+        * apropos.el (apropos-words-to-regexp): Fix algorithm (Bug#13946).
+
 2013-12-18  Glenn Morris  <rgm@gnu.org>
 
         * Makefile.in (BYTE_COMPILE_FLAGS): Set load-prefer-newer to t.
diff --git a/lisp/apropos.el b/lisp/apropos.el
index 7a1a6f6a75a..b7c5aaddcb1 100644
--- a/lisp/apropos.el
+++ b/lisp/apropos.el
@@ -341,16 +341,21 @@ before finding a label."
 
 
 (defun apropos-words-to-regexp (words wild)
-  "Make regexp matching any two of the words in WORDS."
-  (concat "\\("
-          (mapconcat 'identity words "\\|")
-          "\\)"
-          (if (cdr words)
-              (concat wild
-                      "\\("
-                      (mapconcat 'identity words "\\|")
-                      "\\)")
-            "")))
+  "Make regexp matching any two of the words in WORDS.
+WILD should be a subexpression matching wildcards between matches."
+  (setq words (delete-dups (copy-sequence words)))
+  (if (null (cdr words))
+      (car words)
+    (mapconcat
+     (lambda (w)
+       (concat "\\(?:" w "\\)" ;; parens for synonyms
+               wild "\\(?:"
+               (mapconcat 'identity
+                          (delq w (copy-sequence words))
+                          "\\|")
+               "\\)"))
+     words
+     "\\|")))
 
 ;;;###autoload
 (defun apropos-read-pattern (subject)