bug#20257: [PATCH] 24.4.90; set-visited-file-name doesn't reset buffer-auto-save-file-name

[Vitalie Spinu]

Hi,

Do (set-visited-file-name nil) and then rename the buffer. The buffer
will be auto-saved into the old visiting file.

  Vitalie

>From 9b68126dfe58478424ec2b726cc307b1c0d96b1a Mon Sep 17 00:00:00 2001
From: Vitalie Spinu <spinuvit@gmail.com>
Date: Sat, 4 Apr 2015 15:28:07 +0200
Subject: [PATCH] Stop auto-saving after `set-visited-file-name` with nil
 FILENAME

---
 lisp/files.el | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/lisp/files.el b/lisp/files.el
index 42b00ac..7d36608 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -3931,17 +3931,19 @@ the old visited file has been renamed to the new name 
FILENAME."
           (make-local-variable 'backup-inhibited)
           (setq backup-inhibited t)))
     (let ((oauto buffer-auto-save-file-name))
-      ;; If auto-save was not already on, turn it on if appropriate.
-      (if (not buffer-auto-save-file-name)
-         (and buffer-file-name auto-save-default
-              (auto-save-mode t))
-       ;; If auto save is on, start using a new name.
-       ;; We deliberately don't rename or delete the old auto save
-       ;; for the old visited file name.  This is because perhaps
-       ;; the user wants to save the new state and then compare with the
-       ;; previous state from the auto save file.
-       (setq buffer-auto-save-file-name
-             (make-auto-save-file-name)))
+      (cond ((null filename)
+            (setq buffer-auto-save-file-name nil))
+           ((not buffer-auto-save-file-name)
+            ;; If auto-save was not already on, turn it on if appropriate.
+            (and buffer-file-name auto-save-default (auto-save-mode t))
+            (t
+             ;; If auto save is on, start using a new name. We
+             ;; deliberately don't rename or delete the old auto save
+             ;; for the old visited file name.  This is because
+             ;; perhaps the user wants to save the new state and then
+             ;; compare with the previous state from the auto save
+             ;; file.
+             (setq buffer-auto-save-file-name (make-auto-save-file-name)))))
       ;; Rename the old auto save file if any.
       (and oauto buffer-auto-save-file-name
           (file-exists-p oauto)
-- 
2.1.0