bug#74844: m-buffer: Broken Top Directory node in Info manual due to malformed Texinfo direntry

[Eli Zaretskii <eliz@gnu.org>]

> Cc: 74844@debbugs.gnu.org
> Date: Fri, 13 Dec 2024 16:50:02 -0500
> From:  Stefan Monnier via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> > However, the @direntry as
> > noted in the "dir" and "m-buffer-doc.info" files is "* m-buffer.doc."
> 
> Hmm... yup.
> I pushed to Emacs a fix for the generation of that Texinfo element in
> `ox-texinfo.el` and to `m-buffer` I pushed another change which tries to
> workaround that bug (for when it's used with an older Emacs).
> 
> The patch for `ox-texinfo.el` is below.  It's "obviously safe", but
> I suspect it's too late for Emacs-30.  Eli?

Maybe.  For now, I don't think I understand the fix.  What is 'dn' in
this snippet?  The command above says something (which need to be
fixed to follow the code change, btw), but I'm not sure it is accurate
or complete.

An entry in DIR can be either

     * TITLE: (FILE).           DESCRIPTION
or
     * TITLE: (FILE)NODE.       DESCRIPTION

What is 'dn' in the above scheme?  And what is 'file'?

P.S. Should we CC the Org folks on this discussion?