User option to move to another match when changing direction in isearch.

* lisp/isearch.el (isearch-direction-change-changes-match):
New user option (bug#47599).
(isearch-repeat): Use the new option.
(isearch-repeat-forward, isearch-repeat-backward): Adapt to the
new option.

* etc/NEWS: Mention the new user option.

* doc/emacs/search.texi: Document the new user option.

doc/emacs/search.texi

@@ -201,6 +201,14 @@ something before the starting point, type @kbd{C-r} to switch to a
 backward search, leaving the search string unchanged.  Similarly,
 @kbd{C-s} in a backward search switches to a forward search.
 
+@cindex search, changing direction
+@vindex isearch-repeat-on-direction-change
+  When you change the direction of a search, the first command you
+type will, by default, remain on the same match, and the cursor will
+move to the other end of the match.  To move to another match
+immediately, customize the variable
+@code{isearch-repeat-on-direction-change} to @code{t}.
+
 @cindex search, wrapping around
 @cindex search, overwrapped
 @cindex wrapped search

etc/NEWS

@@ -367,6 +367,12 @@ trying to be non-destructive.
 This command opens a new buffer called "*Memory Report*" and gives a
 summary of where Emacs is using memory currently.
 
++++
+** New user option 'isearch-repeat-on-direction-change'.
+When this option is set, direction changes in Isearch move to another
+search match, if there is one, instead of moving point to the other
+end of the current match.
+
 ** Outline
 
 +++

lisp/isearch.el

@@ -185,6 +185,16 @@ When `nil', never wrap, just stop at the last match."
                  (const :tag "Disable wrapping" nil))
   :version "28.1")
 
+(defcustom isearch-repeat-on-direction-change nil
+  "Whether a direction change should move to another match.
+When `nil', the default, a direction change moves point to the other
+end of the current search match.
+When `t', a direction change moves to another search match, if there
+is one."
+  :type '(choice (const :tag "Remain on the same match" nil)
+                 (const :tag "Move to another match" t))
+  :version "28.1")
+
 (defvar isearch-mode-hook nil
   "Function(s) to call after starting up an incremental search.")
 
@@ -1847,6 +1857,8 @@ Use `isearch-exit' to quit without signaling."
 	      (funcall isearch-wrap-function)
 	    (goto-char (if isearch-forward (point-min) (point-max))))))
     ;; C-s in reverse or C-r in forward, change direction.
+    (if (and isearch-other-end isearch-repeat-on-direction-change)
+        (goto-char isearch-other-end))
     (setq isearch-forward (not isearch-forward)
 	  isearch-success t))
 
@@ -1910,10 +1922,12 @@ of the buffer, type \\[isearch-beginning-of-buffer] with a numeric argument."
         (cond ((< count 0)
                (isearch-repeat-backward (abs count))
                ;; Reverse the direction back
-               (isearch-repeat 'forward))
+               (let ((isearch-repeat-on-direction-change nil))
+                 (isearch-repeat 'forward)))
               (t
                ;; Take into account one iteration to reverse direction
-               (when (not isearch-forward) (setq count (1+ count)))
+               (unless isearch-repeat-on-direction-change
+                 (when (not isearch-forward) (setq count (1+ count))))
                (isearch-repeat 'forward count))))
     (isearch-repeat 'forward)))
 
@@ -1931,10 +1945,12 @@ of the buffer, type \\[isearch-end-of-buffer] with a numeric argument."
         (cond ((< count 0)
                (isearch-repeat-forward (abs count))
                ;; Reverse the direction back
-               (isearch-repeat 'backward))
+               (let ((isearch-repeat-on-direction-change nil))
+                 (isearch-repeat 'backward)))
               (t
                ;; Take into account one iteration to reverse direction
-               (when isearch-forward (setq count (1+ count)))
+               (unless isearch-repeat-on-direction-change
+                 (when isearch-forward (setq count (1+ count))))
                (isearch-repeat 'backward count))))
     (isearch-repeat 'backward)))