bug#9528: 24.0.50; Info navigation

[Juri Linkov]

>> >> So if you really insist on having your behavior, then add a custom
>> >> var (which should default to follow the superficial behavior),
>> >> which you can then set in your .emacs.
>> >
>> > Fine with me.
>>
>> Do you think such a custom var should have a broad definition to provide
>> complete compatibility in all functionality with the stand-alone reader
>> or be specific just wrt the behavior of `l'?
>
> I'm not aware of any other compatibility issues.

I found another compatibility issue.

1. Run `emacs -Q'
2. `C-h i m elisp RET g Macros RET'
3. `[' (`Info-backward-node') goes to "Related Topics".
4. `l' goes back to the previously selected node "Macros".

1. Run `info'
2. `m elisp RET g Macros RET'
3. `[' (`Info-backward-node') goes to "Related Topics".
4. `l' goes to the node "Functions", not "Macros".

The behavior of the Emacs Info reader to skip intermediate nodes by default
dates back to the first version of info.el at 1991-07-13.

If you think that behavior of the stand-alone Info reader
is more traditional, we could install this patch:

=== modified file 'lisp/info.el'
--- lisp/info.el        2011-09-18 18:56:22 +0000
+++ lisp/info.el        2011-09-20 16:12:12 +0000
@@ -52,6 +52,15 @@ (defvar Info-history-list nil
   "List of all Info nodes user has visited.
 Each element of the list is a list (FILENAME NODENAME).")
 
+(defcustom Info-history-skip-intermediate-nodes t
+  "Non-nil means don't record intermediate Info nodes to the history.
+Intermediate Info nodes are nodes visited by Info internally in the process of
+searching the node to display.  Intermediate nodes are not presented
+to the user."
+  :type 'boolean
+  :group 'info
+  :version "24.1")
+
 (defcustom Info-enable-edit nil
   "Non-nil means the \\<Info-mode-map>\\[Info-edit] command in Info can edit 
the current node.
 This is convenient if you want to write Info files by hand.
@@ -2673,10 +2682,13 @@ (defun Info-forward-node (&optional not-
                                   "top")))
           (let ((old-node Info-current-node))
             (Info-up)
-            (let (Info-history success)
+            (let ((old-history Info-history)
+                  success)
               (unwind-protect
                   (setq success (Info-forward-node t nil no-error))
-                (or success (Info-goto-node old-node))))))
+                (or success (Info-goto-node old-node)))
+              (if Info-history-skip-intermediate-nodes
+                  (setq Info-history old-history)))))
          (no-error nil)
          (t (error "No pointer forward from this node")))))
 
@@ -2698,10 +2710,12 @@ (defun Info-backward-node ()
           ;; If we move back at the same level,
           ;; go down to find the last subnode*.
           (Info-prev)
-          (let (Info-history)
+          (let ((old-history Info-history))
             (while (and (not (Info-index-node))
                         (save-excursion (search-forward "\n* Menu:" nil t)))
-              (Info-goto-node (Info-extract-menu-counting nil)))))
+              (Info-goto-node (Info-extract-menu-counting nil)))
+            (if Info-history-skip-intermediate-nodes
+                (setq Info-history old-history))))
          (t
           (error "No pointer backward from this node")))))
 
@@ -2757,8 +2771,10 @@ (defun Info-next-preorder ()
         ;; Since logically we are done with the node with that menu,
         ;; move on from it.  But don't add intermediate nodes
         ;; to the history on recursive calls.
-        (let (Info-history)
-          (Info-next-preorder)))
+        (let ((old-history Info-history))
+          (Info-next-preorder)
+          (if Info-history-skip-intermediate-nodes
+              (setq Info-history old-history))))
        (t
         (error "No more nodes"))))
 
@@ -2771,24 +2787,28 @@ (defun Info-last-preorder ()
          ;; so we can scroll back through it.
          (goto-char (point-max)))
         ;; Keep going down, as long as there are nested menu nodes.
-        (let (Info-history) ; Don't add intermediate nodes to the history.
+        (let ((old-history Info-history))
           (while (Info-no-error
                   (Info-last-menu-item)
                   ;; If we go down a menu item, go to the end of the node
                   ;; so we can scroll back through it.
-                  (goto-char (point-max)))))
+                  (goto-char (point-max))))
+          (if Info-history-skip-intermediate-nodes
+              (setq Info-history old-history)))
         (recenter -1))
        ((and (Info-no-error (Info-extract-pointer "prev"))
              (not (equal (Info-extract-pointer "up")
                          (Info-extract-pointer "prev"))))
         (Info-no-error (Info-prev))
         (goto-char (point-max))
-        (let (Info-history) ; Don't add intermediate nodes to the history.
+        (let ((old-history Info-history))
           (while (Info-no-error
                   (Info-last-menu-item)
                   ;; If we go down a menu item, go to the end of the node
                   ;; so we can scroll back through it.
-                  (goto-char (point-max)))))
+                  (goto-char (point-max))))
+          (if Info-history-skip-intermediate-nodes
+              (setq Info-history old-history)))
         (recenter -1))
        ((Info-no-error (Info-up t))
         (goto-char (point-min))