Fix restoring data in visual-line-mode

* lisp/simple.el (visual-line-mode): Only save values once, even
if the mode is switched on twice (bug#43730).  This makes both
previously set local values for variables like truncate-lines, as
well as default values for truncate-lines restorable.

* lisp/emulation/cua-base.el (cua-mode): Ditto.

2 files changed, 16 insertions, 13 deletions

diff --git a/lisp/emulation/cua-base.el b/lisp/emulation/cua-base.el
index c4dcb76446e..926305e6077 100644
--- a/lisp/emulation/cua-base.el
+++ b/lisp/emulation/cua-base.el
@@ -1379,9 +1379,10 @@ the prefix fallback behavior."
 
   (cond
    (cua-mode
-    (setq cua--saved-state
-          (list
-           (and (boundp 'delete-selection-mode) delete-selection-mode)))
+    (unless cua--saved-state
+      (setq cua--saved-state
+            (list
+             (and (boundp 'delete-selection-mode) delete-selection-mode))))
     (if cua-delete-selection
         (delete-selection-mode 1)
       (if (and (boundp 'delete-selection-mode) delete-selection-mode)
diff --git a/lisp/simple.el b/lisp/simple.el
index fef22c2fa6f..05a74d90d62 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -7275,15 +7275,16 @@ Mode' for details."
   :lighter " Wrap"
   (if visual-line-mode
       (progn
-        (set (make-local-variable 'visual-line--saved-state) nil)
-        ;; Save the local values of some variables, to be restored if
-        ;; visual-line-mode is turned off.
-        (dolist (var '(line-move-visual truncate-lines
-                       truncate-partial-width-windows
-                       word-wrap fringe-indicator-alist))
-          (if (local-variable-p var)
-              (push (cons var (symbol-value var))
-                    visual-line--saved-state)))
+        (unless visual-line--saved-state
+          (setq-local visual-line--saved-state (list nil))
+          ;; Save the local values of some variables, to be restored if
+          ;; visual-line-mode is turned off.
+          (dolist (var '(line-move-visual truncate-lines
+                                          truncate-partial-width-windows
+                                          word-wrap fringe-indicator-alist))
+            (if (local-variable-p var)
+                (push (cons var (symbol-value var))
+                      visual-line--saved-state))))
         (set (make-local-variable 'line-move-visual) t)
         (set (make-local-variable 'truncate-partial-width-windows) nil)
         (setq truncate-lines nil
@@ -7297,7 +7298,8 @@ Mode' for details."
     (kill-local-variable 'truncate-partial-width-windows)
     (kill-local-variable 'fringe-indicator-alist)
     (dolist (saved visual-line--saved-state)
-      (set (make-local-variable (car saved)) (cdr saved)))
+      (when (car saved)
+        (set (make-local-variable (car saved)) (cdr saved))))
     (kill-local-variable 'visual-line--saved-state)))
 
 (defun turn-on-visual-line-mode ()