Re: `C-s' `C-s' in Info should pick up search string from `s'

[Juri Linkov]

>     Enhancement request (not a bug):
>
> Would you please hold off on enhancement requests?
> We need to focus on fixing bugs and making the release.

Incidentally, Drew's enhancement request helped me find a bug in isearch.

Typing `C-s C-s' without a previous isearch string leaves the current
buffer in isearch mode after signalling an error.  This is especially
bad with non-nil `debug-on-error', because after quitting the debug
window, `isearch-mode' remains non-nil, but isearch keybindings are
cleared.

How should isearch correctly signal an error?  I think it should use
the standard isearch mechanism for error reporting, i.e. to set
`isearch-error' to the error string which will show it in the isearch
message like:

I-search:  [No previous search string]

and don't exit isearch mode, thus allowing the user to type a new
isearch string.  The patch below implements this.

I also checked isearch.el for other places that use the function
`error' which would cause a similar problem, but didn't find any.
There was only one such problematic place.

Index: lisp/isearch.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/isearch.el,v
retrieving revision 1.275
diff -c -r1.275 isearch.el
*** lisp/isearch.el     29 Sep 2005 22:55:53 -0000      1.275
--- lisp/isearch.el     23 Nov 2005 07:09:36 -0000
***************
*** 1138,1152 ****
        ;; C-s in forward or C-r in reverse.
        (if (equal isearch-string "")
          ;; If search string is empty, use last one.
!         (setq isearch-string
!               (or (if isearch-regexp
!                       (car regexp-search-ring)
!                     (car search-ring))
!                   (error "No previous search string"))
!               isearch-message
!               (mapconcat 'isearch-text-char-description
!                          isearch-string "")
!               isearch-case-fold-search isearch-last-case-fold-search)
        ;; If already have what to search for, repeat it.
        (or isearch-success
            (progn
--- 1150,1165 ----
        ;; C-s in forward or C-r in reverse.
        (if (equal isearch-string "")
          ;; If search string is empty, use last one.
!         (if (null (if isearch-regexp regexp-search-ring search-ring))
!             (setq isearch-error "No previous search string")
!           (setq isearch-string
!                 (if isearch-regexp
!                     (car regexp-search-ring)
!                   (car search-ring))
!                 isearch-message
!                 (mapconcat 'isearch-text-char-description
!                            isearch-string "")
!                 isearch-case-fold-search isearch-last-case-fold-search))
        ;; If already have what to search for, repeat it.
        (or isearch-success
            (progn

-- 
Juri Linkov
http://www.jurta.org/emacs/