bug#30463: 26.0.91; info-lookup-symbol oddities

[Eli Zaretskii <eliz@gnu.org>]

> From: Michael Albinus <michael.albinus@gmx.de>
> Date: Thu, 15 Feb 2018 09:12:28 +0100
> 
> The Emacs manual says in section "26.6.1 Info Documentation Lookup":
> 
> "The major mode determines where to look for documentation for the
> symbol—which Info files to look in, and which indices to search."
> 
> This is not really true. No major mode determines itself "where to look
> for information", this is hard coded in info-look.el.

I think you are misinterpreting what "determines" means in this
context.  It doesn't mean that the mode's code specifies that; it
means that Emacs determines where to look by consulting some data base
that takes the mode into account.

I will see how to reword that to avoid this ambiguity.

> Furthermore, some hard coded locations in info-look.el seem to be
> deprecated. If I, for example, choose manually autoconf-mode as symbol
> help mode, I get (taken from the *Messages* buffer):
> 
> Processing Info node ‘(m4)Macro index’...done
> Processing Info node ‘(autoconf)Autoconf Macro Index’...done
> Processing Info node ‘(autoconf)M4 Macro Index’...done
> Processing Info node ‘(autoconf)Autotest Macro Index’...done
> Processing Info node ‘(autoconf)Macro Index’...
> Cannot access Info node ‘(autoconf)Macro Index’
> Processing Info node ‘(autoconf)Macro Index’...done
> Processing Info node ‘(automake)Macro and Variable Index’...
> Cannot access Info node ‘(automake)Macro and Variable Index’
> Processing Info node ‘(automake)Macro and Variable Index’...done

I'm guessing the missing nodes do exist in some old versions of the
manuals.  I'm not sure Emacs should only support the latest versions
of each manual.  Of course, it would be good to see what replaces
those nodes in the latest manuals, and then _add_ them, but without
removing the old ones.  patches welcome.

Thanks.