Add rename-current-buffer-file and bind it

C-x C-r now renames the current buffer’s file.

init.el

@@ -471,3 +471,25 @@ Version 2016-02-16"
 
 (global-set-key (kbd "<C-return>") 'open-line-below)
 (global-set-key (kbd "<C-S-return>") 'open-line-above)
+
+; Copied from http://whattheemacsd.com/file-defuns.el-01.html
+(defun rename-current-buffer-file ()
+  "Renames current buffer and file it is visiting."
+  (interactive)
+
+  (let ((name (buffer-name))
+        (filename (buffer-file-name)))
+    (if (not (and filename (file-exists-p filename)))
+        (error "Buffer '%s' is not visiting a file!" name)
+      (let ((new-name (read-file-name "New name: " filename)))
+        (if (get-buffer new-name)
+            (error "A buffer named '%s' already exists!" new-name)
+          (rename-file filename new-name 1)
+          (rename-buffer new-name)
+          (set-visited-file-name new-name)
+          ; TODO: this is suspicious for me…
+          (set-buffer-modified-p nil)
+          (message "File '%s' successfully renamed to '%s'"
+                   name (file-name-nondirectory new-name)))))))
+
+(global-set-key (kbd "C-x C-r") 'rename-current-buffer-file)