Autoload 'diff-no-select'

* lisp/emacs-lisp/package.el (package-review): Remove
unnecessary 'require'.
* lisp/eshell/em-unix.el: Remove declaration.
* lisp/files.el (save-some-buffers-action-alist): Remove
unnecessary 'require'.
* lisp/vc/diff.el (diff-no-select): Autoload it.

(Bug#80288)

lisp/emacs-lisp/package.el

@@ -748,7 +748,6 @@ wants to review the package prior to installation.  See `package-review'."
 
 (declare-function mail-text "sendmail" ())
 (declare-function message-goto-body "message" (&optional interactive))
-(declare-function diff-no-select "diff" (old new &optional switches no-async buf))
 
 (defun package-review (pkg-desc pkg-dir old-desc)
   "Review the package specified PKG-DESC which is about to be installed.
@@ -781,7 +780,6 @@ attached."
                                            (package-desc-full-name pkg-desc)))))
               t)
              (?m
-              (require 'diff)             ;for `diff-no-select'
               (with-temp-buffer
                 (diff-no-select
                  (package-desc-dir old-desc) pkg-dir

lisp/eshell/em-unix.el

@@ -1013,8 +1013,6 @@ Show wall-clock time elapsed during execution of COMMAND.")
     ((string-match "[^[:blank:]]" string) string)
     (nil)))
 
-(autoload 'diff-no-select "diff")
-
 (defun eshell/diff (&rest args)
   "Alias \"diff\" to call Emacs `diff' function."
   (let ((orig-args (eshell-stringify-list (flatten-tree args))))

lisp/files.el

@@ -6351,9 +6351,6 @@ Before and after saving the buffer, this function runs
 	      (setq buffer-backed-up nil)))))))
     setmodes))
 
-(declare-function diff-no-select "diff"
-		  (old new &optional switches no-async buf))
-
 (defvar save-some-buffers--switch-window-callback nil)
 
 (defvar save-some-buffers-action-alist
@@ -6384,7 +6381,6 @@ Before and after saving the buffer, this function runs
     (?d ,(lambda (buf)
            (if (null (buffer-file-name buf))
                (message "Not applicable: no file")
-             (require 'diff)            ;for diff-no-select.
              (let ((diffbuf (diff-no-select (buffer-file-name buf) buf
                                             nil 'noasync)))
                (if (not enable-recursive-minibuffers)

lisp/vc/diff.el

@@ -154,6 +154,7 @@ Possible values are:
 		    (call-process diff-command nil t nil "--help"))
 	      (if (search-backward "--label" nil t) t))))))
 
+;;;###autoload
 (defun diff-no-select (old new &optional switches no-async buf)
   ;; Noninteractive helper for creating and reverting diff buffers
   "Compare the OLD and NEW file/buffer.