info-lookup-symbol index case sensitivity

[Kevin Ryde <user42@zip.com.au>]

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In GNU Emacs 21.1.1 (i386-debian-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2001-12-07 on raven, modified by Debian
configured using `configure  i386-debian-linux-gnu --prefix=/usr --sharedstatedir=/var/lib --libexecdir=/usr/lib --localstatedir=/var/lib --infodir=/usr/share/info --mandir=/usr/share/man --with-pop=yes --with-x=yes --with-x-toolkit=athena --without-gif'
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: nil
  locale-coding-system: nil
  default-enable-multibyte-characters: t

When the help-data in info-lookup-alist specifies that symbols are
case-sensitive, the index search performed by info-lookup-symbol (C-h
C-i) is instead case-insensitive when searching through index entries.

I'm not aware of any of the manuals in the supplied info-look.el which
have two index entries differing only in case.  But I encountered the
problem while setting up some sh-mode data.  bash.info has a variable
"GROUPS", and sh-utils.info has the program "groups".


The problem can be illustrated with a contrived foo.info below, having
index entries "foo" and "FOO".  Put it and the foo.el below in an
otherwise empty directory and run

	emacs -q -no-site-file -l foo.el

foo.el sets up foo.info as case-sensitive help for fundamental-mode,
and leaves such a buffer with "FOO" and "foo" ready to be looked up
with C-h C-i.

Press C-h C-i on either "FOO" or "foo" and notice that both bring up
the node for lower case "foo", whereas I believe for "FOO" it ought to
bring up the upper case FOO node.


I think this is just a problem with the searching in info-lookup,
since info-lookup-cache records the available index entries in their
correct case.

In fact I believe the use of Info-menu in info-lookup might be the
problem, since it forcibly binds case-fold-search to t.  No doubt
that's good for interactive use, but it's not what info-lookup wants.


I get some joy from the info-lookup.el.diff below, doing a
case-sensitive search in the index node to get to the right spot.

	* info-look.el (info-lookup): Replace Info-menu call with a case
	sensitive search of the index, to preserve sensitivity requested
	by the help data.

I believe this is correct for case-insensitive help modes too, since
the index entries in info-lookup-cache are recorded with their case
unchanged, only the symbols to which they refer are downcased.



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*** info-look.el.~1.27.~	Sat Jul 27 08:07:16 2002
--- info-look.el	Tue Dec  3 19:41:37 2002
*************** (defun info-lookup (topic item mode)
*** 356,362 ****
  		 nil))
  	  (condition-case nil
  	      (progn
! 		(Info-menu (or (cdr entry) item))
  		(setq found t)
  		(if (or prefix suffix)
  		    (let ((case-fold-search
--- 356,366 ----
  		 nil))
  	  (condition-case nil
  	      (progn
!                 ;; Don't use Info-menu, it forces case-fold-search to nil
!                 (let ((case-fold-search nil))
!                   (re-search-forward
!                    (concat "^\\* " (regexp-quote (or (cdr entry) item)) ":")))
!                 (Info-follow-nearest-node)
  		(setq found t)
  		(if (or prefix suffix)
  		    (let ((case-fold-search