* lisp/isearch.el: Rename search-default-regexp-mode to search-default-mode

(search-default-mode): New variable.
(isearch-mode, isearch-define-mode-toggle)
(isearch--describe-regexp-mode): Update accordingly.
* lisp/menu-bar.el (nonincremental-search-forward): Update accordingly.
* etc/NEWS: Update accordingly.
* doc/emacs/search.texi: Update accordingly.

doc/emacs/search.texi

@@ -1268,7 +1268,7 @@ character sequences}.
   Generally, search commands in Emacs by default perform character
 folding, thus matching equivalent character sequences.  You can
 disable this behavior by customizing the variable
-@code{search-default-regexp-mode} to @code{nil}.  @xref{Search
+@code{search-default-mode} to @code{nil}.  @xref{Search
 Customizations}.  Within an incremental search, typing @kbd{M-s '}
 (@code{isearch-toggle-character-fold}) toggles character folding, but
 only for that search.  (Replace commands have a different default,
@@ -1800,7 +1800,7 @@ not described elsewhere.
 @cindex default search mode
 @cindex search mode, default
   The default search mode for the incremental search is specified by
-the variable @code{search-default-regexp-mode}.  It can be @code{nil},
+the variable @code{search-default-mode}.  It can be @code{nil},
 @code{t}, or a function.  If it is @code{nil}, the default mode is to
 do literal searches without character folding, but with case folding
 and lax-whitespace matches as determined by @code{case-fold-search}

etc/NEWS

@@ -586,7 +586,7 @@ item as before.
 ** Search and Replace
 
 +++
-*** New user option `search-default-regexp-mode'
+*** New user option `search-default-mode'
 specifies the default mode for I-search.
 
 +++

lisp/isearch.el

@@ -224,7 +224,7 @@ Default value, nil, means edit the string instead."
 
 (autoload 'character-fold-to-regexp "character-fold")
 
-(defcustom search-default-regexp-mode #'character-fold-to-regexp
+(defcustom search-default-mode #'character-fold-to-regexp
   "Default mode to use when starting isearch.
 Value is nil, t, or a function.
 
@@ -868,11 +868,11 @@ used to set the value of `isearch-regexp-function'."
   (setq isearch-forward forward
 	isearch-regexp (or regexp
                            (and (not regexp-function)
-                                (eq search-default-regexp-mode t)))
+                                (eq search-default-mode t)))
 	isearch-regexp-function (or regexp-function
-                                    (and (functionp search-default-regexp-mode)
+                                    (and (functionp search-default-mode)
                                          (not regexp)
-                                         search-default-regexp-mode))
+                                         search-default-mode))
 	isearch-op-fun op-fun
 	isearch-last-case-fold-search isearch-case-fold-search
 	isearch-case-fold-search case-fold-search
@@ -1506,7 +1506,7 @@ Use `isearch-exit' to quit without signaling."
   (isearch-repeat 'backward))
 
 
-;;; Toggles for `isearch-regexp-function' and `search-default-regexp-mode'.
+;;; Toggles for `isearch-regexp-function' and `search-default-mode'.
 (defmacro isearch-define-mode-toggle (mode key function &optional docstring &rest body)
   "Define a command called `isearch-toggle-MODE' and bind it to `M-s KEY'.
 The first line of the command's docstring is auto-generated, the
@@ -1538,7 +1538,7 @@ The command then executes BODY and updates the isearch prompt."
              (cl-callf (lambda (types) (cons 'choice
                                         (cons '(const :tag ,(capitalize (format "%s search" mode)) ,function)
                                               (cdr types))))
-                 (get 'search-default-regexp-mode 'custom-type)))))))
+                 (get 'search-default-mode 'custom-type)))))))
 
 (isearch-define-mode-toggle word "w" word-search-regexp "\
 Turning on word search turns off regexp mode.")
@@ -2571,7 +2571,7 @@ the word mode."
     (setq regexp-function #'word-search-regexp))
   (let ((description
          ;; Don't use a description on the default search mode.
-         (cond ((equal regexp-function search-default-regexp-mode) "")
+         (cond ((equal regexp-function search-default-mode) "")
                (regexp-function
                 (and (symbolp regexp-function)
                      (or (get regexp-function 'isearch-message-prefix)
@@ -2579,7 +2579,7 @@ the word mode."
                (isearch-regexp "regexp ")
                ;; We're in literal mode. If the default mode is not
                ;; literal, then describe it.
-               ((functionp search-default-regexp-mode) "literal "))))
+               ((functionp search-default-mode) "literal "))))
     (if space-before
         ;; Move space from the end to the beginning.
         (replace-regexp-in-string "\\(.*\\) \\'" " \\1" description)

lisp/menu-bar.el

@@ -244,7 +244,7 @@
   (setq menu-bar-last-search-type 'string)
   ;; Ideally, this whole command would be equivalent to `C-s RET'.
   (let ((isearch-forward (not backward))
-        (isearch-regexp-function search-default-regexp-mode)
+        (isearch-regexp-function search-default-mode)
         (isearch-regexp nil))
     (if (or (equal string "") (not string))
         (funcall (isearch-search-fun-default) (car search-ring))