Avoid adverse side effects of fixing bug#21824

* test/src/buffer-tests.el
(overlay-modification-hooks-deleted-overlay): New test.

* src/buffer.c (report_overlay_modification): Don't bypass all
the overlay-modification hooks; instead, invoke each function
only if the buffer associated with the overlay is the current
buffer.  (Bug#30823)

1 files changed, 19 insertions, 0 deletions

diff --git a/test/src/buffer-tests.el b/test/src/buffer-tests.el
index f9c477fbfd7..8479bbdda0b 100644
--- a/test/src/buffer-tests.el
+++ b/test/src/buffer-tests.el
@@ -45,6 +45,25 @@ with parameters from the *Messages* buffer modification."
             (should (eq buf (current-buffer))))
         (when msg-ov (delete-overlay msg-ov))))))
 
+(ert-deftest overlay-modification-hooks-deleted-overlay ()
+  "Test for bug#30823."
+  (let ((check-point nil)
+        (ov-delete nil)
+        (ov-set nil))
+    (with-temp-buffer
+      (insert "abc")
+      (setq ov-set (make-overlay 1 3))
+      (overlay-put ov-set 'modification-hooks
+                   (list (lambda (_o after &rest _args)
+                           (and after (setq check-point t)))))
+      (setq ov-delete (make-overlay 1 3))
+      (overlay-put ov-delete 'modification-hooks
+                   (list (lambda (o after &rest _args)
+                           (and (not after) (delete-overlay o)))))
+      (goto-char 2)
+      (insert "1")
+      (should (eq check-point t)))))
+
 (ert-deftest test-generate-new-buffer-name-bug27966 ()
   (should-not (string-equal "nil"
                             (progn (get-buffer-create "nil")