bug#14717: 24.3.50; Info-try-follow-nearest-node misses some footnotes

[Juri Linkov <juri@jurta.org>]

>> BTW, if you are interested what I'm trying to do in bug#14670
>> where I renamed the text property of footnotes from `link' to `shr-url'
>> is to support shr-url links in Info.  The value of the text properly
>> `shr-url' is the target of the link.  The problem is how to address
>> a footnote?  Maybe add a function that finds a footnote.  But I'm afraid
>> that supporting an arbitrary function on the text properly `shr-url'
>> is too unsafe.  So `shr-url' should contain only a string.  The question
>> is in what format to specify a link to a footnote.  Currently it has
>> the value `t'.  Perhaps as a string it could contain a line number
>> of the footnote like "(elisp) Using Interactive (line 42)".
>
> Would that mean the link would have to be manually updated whenever the
> line number of the footnote in the file changes?  If so, it seems
> error-prone.  But I don't know the implementation, maybe that's not an
> issue.  Otherwise, seems like an interesting idea.

`Info-fontify-node' could calculate the line number dynamically
before putting it to the text property `link', but since I have
no idea in what format to put line numbers in links, I'll leave
it unchanged for now.

The main point for bug#14670 is to put a new condition
that checks general links to `Info-try-follow-nearest-node'
either after checking for footnotes, or before checking
for footnotes but with an additional condition

  `(not (eq node t))'

because for footnotes `Info-fontify-node' puts the text property `link'
with the value `t' that should be skipped when the current link
is a link to footnote and not a general link, so another existing
`cond' branch will check whether text at point contains a link for footnote.
I see no problems for footnotes after adding processing of general links
with this patch:

=== modified file 'lisp/info.el'
--- lisp/info.el	2013-06-27 09:20:04 +0000
+++ lisp/info.el	2013-06-27 23:31:27 +0000
@@ -3863,6 +3919,8 @@ (defun Info-try-follow-nearest-node (&op
 If FORK is non-nil, it is passed to `Info-goto-node'."
   (let (node)
     (cond
+     ((and (setq node (get-text-property (point) 'link)) (not (eq node t)))
+      (Info-goto-node node fork))
      ((setq node (Info-get-token (point) "[hf]t?tps?://"
 				 "\\([hf]t?tps?://[^ \t\n\"`({<>})']+\\)"))
       (browse-url node)