Improve completion behavior of info-display-manual.

* lisp/info.el (info-display-manual): Add existing Info buffers, whose
files may not be in Info-directory-list, to the completion.
(info--manual-names): New helper function.

2 files changed, 21 insertions, 3 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 45fa38042a0..77eed9ed918 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2012-12-05  Chong Yidong  <cyd@gnu.org>
+
+        * info.el (info-display-manual): Add existing Info buffers, whose
+        files may not be in Info-directory-list, to the completion.
+        (info--manual-names): New helper function.
+
 2012-12-05  Glenn Morris  <rgm@gnu.org>
 
         * vc/vc-hg.el (vc-hg-resolve-when-done, vc-hg-find-file-hook):
diff --git a/lisp/info.el b/lisp/info.el
index 6149c3fcd80..2c2d485e245 100644
--- a/lisp/info.el
+++ b/lisp/info.el
@@ -5105,9 +5105,7 @@ Otherwise, visit the manual in a new Info buffer."
     (progn
       (info-initialize)
       (completing-read "Manual name: "
-                       (apply-partially 'Info-read-node-name-2
-                                        Info-directory-list
-                                        (mapcar 'car Info-suffix-list))
+                       (info--manual-names)
                        nil t))))
   (let ((blist (buffer-list))
         (manual-re (concat "\\(/\\|\\`\\)" manual "\\(\\.\\|\\'\\)"))
@@ -5126,6 +5124,20 @@ Otherwise, visit the manual in a new Info buffer."
       (info (Info-find-file manual)
             (generate-new-buffer-name "*info*")))))
 
+(defun info--manual-names ()
+  (let (names)
+    (dolist (buffer (buffer-list))
+      (with-current-buffer buffer
+        (and (eq major-mode 'Info-mode)
+             (stringp Info-current-file)
+             (push (file-name-sans-extension
+                    (file-name-nondirectory Info-current-file))
+                   names))))
+    (delete-dups (append (nreverse names)
+                         (apply-partially 'Info-read-node-name-2
+                                          Info-directory-list
+                                          (mapcar 'car Info-suffix-list))))))
+
 (provide 'info)
 
 ;;; info.el ends here