whitespace: Use `define-globalized-minor-mode' for global mode

* lisp/whitespace.el (global-whitespace-mode): Fix interoperability
between `whitespace-mode' and `global-whitespace-mode' by using
`define-globalized-minor-mode'.  (Bug#60334)
* test/lisp/whitespace-tests.el (whitespace-tests--global): Add a
regression test.

2 files changed, 24 insertions, 29 deletions

diff --git a/lisp/whitespace.el b/lisp/whitespace.el
index 558be1841ab..7a30274a330 100644
--- a/lisp/whitespace.el
+++ b/lisp/whitespace.el
@@ -1014,34 +1014,11 @@ See also `whitespace-newline' and `whitespace-display-mappings'."
 
 
 ;;;###autoload
-(define-minor-mode global-whitespace-mode
-  "Toggle whitespace visualization globally (Global Whitespace mode).
-
-See also `whitespace-style', `whitespace-newline' and
-`whitespace-display-mappings'."
-  :lighter    " WS"
+(define-globalized-minor-mode global-whitespace-mode
+  whitespace-mode
+  whitespace-turn-on-if-enabled
   :init-value nil
-  :global     t
-  :group      'whitespace
-  (cond
-   (noninteractive                      ; running a batch job
-    (setq global-whitespace-mode nil))
-   (global-whitespace-mode              ; global-whitespace-mode on
-    (save-current-buffer
-      (add-hook 'find-file-hook 'whitespace-turn-on-if-enabled)
-      (add-hook 'after-change-major-mode-hook 'whitespace-turn-on-if-enabled)
-      (dolist (buffer (buffer-list))    ; adjust all local mode
-        (set-buffer buffer)
-        (unless whitespace-mode
-          (whitespace-turn-on-if-enabled)))))
-   (t                                   ; global-whitespace-mode off
-    (save-current-buffer
-      (remove-hook 'find-file-hook 'whitespace-turn-on-if-enabled)
-      (remove-hook 'after-change-major-mode-hook 'whitespace-turn-on-if-enabled)
-      (dolist (buffer (buffer-list))    ; adjust all local mode
-        (set-buffer buffer)
-        (unless whitespace-mode
-          (whitespace-turn-off)))))))
+  :group 'whitespace)
 
 (defvar whitespace-enable-predicate
   (lambda ()
@@ -1067,7 +1044,7 @@ This variable is normally modified via `add-function'.")
 
 (defun whitespace-turn-on-if-enabled ()
   (when (funcall whitespace-enable-predicate)
-    (whitespace-turn-on)))
+    (whitespace-mode)))
 
 ;;;###autoload
 (define-minor-mode global-whitespace-newline-mode
@@ -2511,7 +2488,7 @@ purposes)."
         (setq whitespace-display-table-was-local t)
         ;; Save the old table so we can restore it when
         ;; `whitespace-mode' is switched off again.
-        (when (or whitespace-mode global-whitespace-mode)
+        (when whitespace-mode
           (setq whitespace-display-table
                 (copy-sequence buffer-display-table)))
         ;; Assure `buffer-display-table' is unique
diff --git a/test/lisp/whitespace-tests.el b/test/lisp/whitespace-tests.el
index d72748cd0c9..3a53e025036 100644
--- a/test/lisp/whitespace-tests.el
+++ b/test/lisp/whitespace-tests.el
@@ -57,6 +57,24 @@ buffer's content."
     (whitespace-cleanup)
     (buffer-string)))
 
+(ert-deftest whitespace-tests--global ()
+  (let ((backup global-whitespace-mode)
+        (noninteractive nil)
+        (whitespace-enable-predicate (lambda () t)))
+    (unwind-protect
+        (progn
+          (global-whitespace-mode 1)
+          (ert-with-test-buffer-selected ()
+            (normal-mode)
+            (should whitespace-mode)
+            (global-whitespace-mode -1)
+            (should (null whitespace-mode))
+            (whitespace-mode 1)
+            (should whitespace-mode)
+            (global-whitespace-mode 1)
+            (should whitespace-mode)))
+      (global-whitespace-mode (if backup 1 -1)))))
+
 (ert-deftest whitespace-cleanup-eob ()
   (let ((whitespace-style '(empty)))
     (should (equal (whitespace-tests--cleanup-string "a\n")