3 files changed, 5 insertions, 34 deletions
diff --git a/lisp/emacs-lisp/cl-lib.el b/lisp/emacs-lisp/cl-lib.el
index 4208160bd12..4645b4dffb1 100644
--- a/lisp/emacs-lisp/cl-lib.el
+++ b/lisp/emacs-lisp/cl-lib.el
@@ -154,12 +154,10 @@ to an element already in the list stored in PLACE.
 	`(setq ,place (cl-adjoin ,x ,place ,@keys)))
     `(cl-callf2 cl-adjoin ,x ,place ,@keys)))
 
-(defun cl--set-buffer-substring (start end val)
+(defun cl--set-buffer-substring (start end val &optional inherit)
   "Delete region from START to END and insert VAL."
-  (save-excursion (delete-region start end)
-		  (goto-char start)
-		  (insert val)
-		  val))
+  (replace-region-contents start end val 0 nil inherit)
+  val)
 
 (defun cl--set-substring (str start end val)
   (if end (if (< end 0) (incf end (length str)))
diff --git a/lisp/emacs-lisp/gv.el b/lisp/emacs-lisp/gv.el
index b44f7dc87f3..6c949f1016b 100644
--- a/lisp/emacs-lisp/gv.el
+++ b/lisp/emacs-lisp/gv.el
@@ -684,6 +684,8 @@ REF must have been previously obtained with `gv-ref'."
   `(insert (prog1 ,store (erase-buffer))))
 (make-obsolete-generalized-variable 'buffer-string nil "29.1")
 
+;; FIXME: Can't use `replace-region-contents' because it's not
+;; expected to be costly, so we need to pass MAX-SECS==0.
 (gv-define-simple-setter buffer-substring cl--set-buffer-substring)
 (make-obsolete-generalized-variable 'buffer-substring nil "29.1")
 
diff --git a/lisp/emacs-lisp/subr-x.el b/lisp/emacs-lisp/subr-x.el
index 6414ecab394..eaa8119ead7 100644
--- a/lisp/emacs-lisp/subr-x.el
+++ b/lisp/emacs-lisp/subr-x.el
@@ -281,35 +281,6 @@ the string."
   (declare (pure t) (side-effect-free t))
   (string-remove-suffix "\n" string))
 
-(defun replace-region-contents (beg end replace-fn
-                                    &optional max-secs max-costs)
-  "Replace the region between BEG and END using REPLACE-FN.
-REPLACE-FN runs on the current buffer narrowed to the region.  It
-should return either a string or a buffer replacing the region.
-
-The replacement is performed using `replace-buffer-contents'
-which also describes the MAX-SECS and MAX-COSTS arguments and the
-return value.
-
-Note: If the replacement is a string, it'll be placed in a
-temporary buffer so that `replace-buffer-contents' can operate on
-it.  Therefore, if you already have the replacement in a buffer,
-it makes no sense to convert it to a string using
-`buffer-substring' or similar."
-  (save-excursion
-    (save-restriction
-      (narrow-to-region beg end)
-      (goto-char (point-min))
-      (let ((repl (funcall replace-fn)))
-	(if (bufferp repl)
-	    (replace-buffer-contents repl max-secs max-costs)
-	  (let ((source-buffer (current-buffer)))
-	    (with-temp-buffer
-	      (insert repl)
-	      (let ((tmp-buffer (current-buffer)))
-		(set-buffer source-buffer)
-		(replace-buffer-contents tmp-buffer max-secs max-costs)))))))))
-
 ;;;###autoload
 (defmacro named-let (name bindings &rest body)
   "Looping construct taken from Scheme.