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, 6 insertions, 18 deletions

diff --git a/src/buffer.c b/src/buffer.c
index b0cee717036..179360c5622 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -4543,23 +4543,6 @@ report_overlay_modification (Lisp_Object start, Lisp_Object end, bool after,
     Lisp_Object *copy;
     ptrdiff_t i;
 
-    if (size)
-      {
-        Lisp_Object ovl
-          = XVECTOR (last_overlay_modification_hooks)->contents[1];
-
-        /* If the buffer of the first overlay in the array doesn't
-           match the current buffer, then these modification hooks
-           should not be run in this buffer.  This could happen when
-           some code calls some insdel functions, such as del_range_1,
-           with the PREPARE argument false -- in that case this
-           function is never called to record the overlay modification
-           hook functions in the last_overlay_modification_hooks
-           array, so anything we find there is not ours.  */
-        if (XMARKER (OVERLAY_START (ovl))->buffer != current_buffer)
-          return;
-      }
-
     USE_SAFE_ALLOCA;
     SAFE_ALLOCA_LISP (copy, size);
     memcpy (copy, XVECTOR (last_overlay_modification_hooks)->contents,
@@ -4570,7 +4553,12 @@ report_overlay_modification (Lisp_Object start, Lisp_Object end, bool after,
         Lisp_Object prop_i, overlay_i;
         prop_i = copy[i++];
         overlay_i = copy[i++];
-        call_overlay_mod_hooks (prop_i, overlay_i, after, arg1, arg2, arg3);
+        /* It is possible that the recorded overlay has been deleted
+           (which makes it's markers' buffers be nil), or that (due to
+           some bug) it belongs to a different buffer.  Only run this
+           hook if the overlay belongs to the current buffer.  */
+        if (XMARKER (OVERLAY_START (overlay_i))->buffer == current_buffer)
+          call_overlay_mod_hooks (prop_i, overlay_i, after, arg1, arg2, arg3);
       }
 
     SAFE_FREE ();