Re: info: prev-line and scroll-backward are buggy on gnuplot.info

[Eli Zaretskii]

> Date: Sat, 12 Nov 2022 00:17:34 +0100
> From: Vincent Lefevre <vincent@vinc17.net>
> Cc: 989029@bugs.debian.org
> 
> [Cc to the Debian bug 989029, which I reported last year:
> 
>   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=989029
> 
> I'm now reporting it upstream since it still occurs with "info"
> from Texinfo 7.0.]

AFAIU, this is not a bug with Texinfo, see below.

> * gnuplot::
> * plotting_styles::
> * Commands::
> * Terminal_types::
> * Bugs::
> * Concept_Index::
> * Command_Index::
> * Options_Index::
> * Function_Index::
> * Terminal_Index::
> 
> Go to "Bugs". This gives
> 
> ------------------------------------------------------------------------
> Next: Concept_Index,  Prev: Terminal_types,  Up: Top
> 
> 5 Bugs
> ******
> 
> Please e-mail bug reports to the gnuplot-bugs mailing list or upload the
> report to the gnuplot web site on SourceForge.  Please give complete
> information on the version of gnuplot you are using and, if possible, a
> test script that demonstrates the bug.  See 'seeking-assistance'.
> 
> * Menu:
> 
> * known_limitations::
> * External_libraries::
> ------------------------------------------------------------------------
> 
> Then do a scroll-backward (with the Backspace or PageUp key) or a
> prev-line (with the up arrow key). This gives:
> 
> ------------------------------------------------------------------------
> 5.2 External libraries
> ======================
> [...]
> ------------------------------------------------------------------------
> 
> instead of going to Terminal_types.
> 
> Going to the previous node gives successively:
> 
> 5 Bugs
> 5.2 External libraries
> 5.1 known limitations
> 5 Bugs

Instead of "Bugs", go to "Graphical_User_Interfaces" from the
top-level menu.  You will see this:

  4 Graphical User Interfaces
  ***************************

  Several graphical user interfaces have been written for `gnuplot` and
  one for win32 is included in this distribution.  In addition, there is
  a Python interface at http://py-gnuplot.darwinports.com/
  (http://py-gnuplot.darwinports.com/)

     Also several X11 interfaces exist.  One of them is called xgfe. It
  uses the Qt library and can be found on
  http://www.flash.net/~dmishee/xgfe/xgfe.html
  (http://www.flash.net/~dmishee/xgfe/xgfe.html)

     In addition three Tcl/Tk located at the usual Tcl/Tk repositories
  exist.

     Bruce Ravel (ravel@phys.washington.edu) has written a new version of
  gnuplot-mode for GNU emacs and XEmacs. This version is based on the
  gnuplot.el file by Gershon Elber.  While the gnuplot CVS repository has
  its own copy the most recent version of this package is available from
  http://feff.phys.washington.edu/~ravel/software/gnuplot-mode/
  (http://feff.phys.washington.edu/~ravel/software/gnuplot-mode/)

  * Menu:

  * Bugs::

See that "Bugs" at the end?  This is the problem: since "Bugs" is a
top-level node, its presence in a level-1 node's menu makes the node
tree not really a tree, so Backspace loops.

Thus, the problem is in the way Gnuplot produces the Info manual from
its documentation sources.  This bug should be submitted to the
Gnuplot project.