[spacemacs-defaults] Move new function to correct file

doc/DOCUMENTATION.org

@@ -2521,6 +2521,7 @@ File manipulation commands (start with ~f~):
 | Key binding | Description                                                                                            |
 |-------------+--------------------------------------------------------------------------------------------------------|
 | ~SPC f A~   | open a file and replace the current buffer with the new file                                           |
+| ~SPC f a~   | open a file and open it in a new buffer leaving the old buffer untouched                               |
 | ~SPC f b~   | go to file bookmarks                                                                                   |
 | ~SPC f c~   | copy current file to a different location                                                              |
 | ~SPC f C d~ | convert file from unix to dos encoding                                                                 |

layers/+spacemacs/spacemacs-defaults/funcs.el

@@ -510,6 +510,24 @@ initialized with the current directory instead of filename."
         (spacemacs/rename-buffer-visiting-a-file arg)
       (spacemacs/rename-buffer-or-save-new-file))))
 
+(defun spacemacs/save-file-as-and-open (filename)
+  "Save current buffer into file FILENAME and open it in a new buffer."
+  (interactive
+   (list (if buffer-file-name
+             (read-file-name "Save file as and open: " buffer-file-name)
+           (read-file-name "Save file as and open: " default-directory))))
+  (or (null filename) (string-equal filename "")
+      (progn
+        (let ((dir (file-name-directory filename)))
+          (when (and (not (file-exists-p dir))
+                     (yes-or-no-p (format "Create directory '%s'?" dir)))
+            (make-directory dir t)))
+        (and (file-exists-p filename)
+             (or (y-or-n-p (format "File `%s' exists; overwrite? " filename))
+                 (error "Canceled")))
+        (write-region (point-min) (point-max) filename)
+        (find-file filename))))
+
 (defun spacemacs/show-hide-helm-or-ivy-prompt-msg (msg sec)
   "Show a MSG at the helm or ivy prompt for SEC.
 With Helm, remember the path, then restore it after SEC.

layers/+spacemacs/spacemacs-defaults/keybindings.el

@@ -361,7 +361,7 @@
  :global
  (("f" "Files"
    ("A" spacemacs/find-file-and-replace-buffer "Set another file for buffer...")
-   ("a" spacemacs/save-file-as-and-open "Save current buffer and open in new buffer...")
+   ("a" spacemacs/save-file-as-and-open "Copy file to new: file and buffer...")
    ("c" spacemacs/copy-file "Copy file to new file...")
    ("D" spacemacs/delete-current-buffer-file "Delete...")
    ("i" spacemacs/insert-file "Insert file content...")
@@ -389,8 +389,8 @@
    ("v" "Variables"
     ("d" add-dir-local-variable "Add directory-local variable...")
     ("f" add-file-local-variable "Add bottom file variable...")
-    ("p" add-file-local-variable-prop-line "Add top file property...")
-    )
+    ("p" add-file-local-variable-prop-line "Add top file property..."))
+
    ("y" "Yank/Copy"
     ("c" spacemacs/copy-file-path-with-line-column "File path with line and column")
     ("d" spacemacs/copy-directory-path "Directory path")