Re: Disappointed by texinfo @anchor construct

[Alan <wehmann@fnal.gov>]

On Thursday, November 20, 2014 11:30:10 AM UTC-6, Eli Zaretskii wrote:
> > Date: Wed, 19 Nov 2014 19:45:10 -0800 (PST)
> > From: Alan <wehmann_at_fnal.gov>
> > 
> > I've been checking which makeinfo I am using.  I did the latest testing with makeinfo from texinfo 5.2.
> 
> Pick up an anchor that doesn't work, then visit the Info file
> literally, and look up that anchor in the Tag Table at the end of the
> file.  It should have the byte offset near it.  Check where does this
> byte offset point to in the file.  If it points to the correct place,
> then makeinfo is innocent.
> 
> Can you try with some other file, like wisent.info that comes with
> Emacs?  I just tried there, and the anchor wisent-skip-token,
> referenced from the node "Error Recovery", works for me.  Does it work
> for you?

The offset looks okay.  I tried wisent.info and the problem remains.

I then decided to explore the operation of the code, with edebug.  I record my observations below:

I explored code using edebug and found the critical section of code in

(defun Info-find-node-2

To be able to reference particular lines, I added a number at the beginning of each line:

1              ;; First, search a tag table, if any
2              (when (marker-position Info-tag-table-marker)
3                (let* ((m Info-tag-table-marker)
4                       (found (Info-find-in-tag-table m regexp strict-case)))
5
6                  (when found
7                    ;; FOUND is (ANCHOR POS MODE).
8                    (setq guesspos (nth 1 found))
9
10                    ;; If this is an indirect file, determine which
11                    ;; file really holds this node and read it in.
12                    (unless (eq (nth 2 found) 'Info-mode)
13                      ;; Note that the current buffer must be the
14                      ;; *info* buffer on entry to
15                      ;; Info-read-subfile.  Thus the hackery above.
16                      (setq guesspos (Info-read-subfile guesspos)))
17
18                    ;; Handle anchor
19                    (when (nth 0 found)
20                      (goto-char (setq anchorpos guesspos))
21                      (throw 'foo t)))))

I have a texinfo file of mine where I've added an anchor & then ran it through makeinfo.  I looked at the tag table for that anchor in the info file and it has an offset that makes sense.  I then examine what happens in the above section of code--using edebug--when I reference that anchor.  At line 8 the guesspos is what I would regard as proper for the anchor.  The test at line 12 fails because the mode recorded in "found" is "fundamental".  Line 16 then changes guesspos to a value that doesn't correspond to the anchor.

My next task is to figure out why the mode recorded in "found" isn't 'Info-mode.