From 0e9cee2bf5d97a23c47d99ffc47396dcd3bd50ee Mon Sep 17 00:00:00 2001
From: Spencer Baugh <sbaugh@janestreet.com>
Date: Thu, 28 Aug 2025 14:13:24 -0400
Subject: [PATCH] Ignore keymaps at point for positions outside the buffer

Correct a few edge cases where we used the keymaps at point when
looking up keymaps for an event position which is outside the
current buffer.  Namely:

- Clicking on a part of the mode line which is after the end of
  mode-line-format produces an event with non-nil posn-area but
  nil posn-string.

- Even if posn-string doesn't have a local keymap, we should
  still ignore the keymaps at point if posn-string is non-nil.

* src/keymap.c (Fcurrent_active_maps): Ignore keymaps at point
for more positions outside the buffer.  (bug#76620)
---
 src/keymap.c             | 38 ++++++++++++++++----------------------
 test/src/keymap-tests.el | 27 +++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 22 deletions(-)

diff --git a/src/keymap.c b/src/keymap.c
index 2c250578b00..295b209f06b 100644
--- a/src/keymap.c
+++ b/src/keymap.c
@@ -1735,11 +1735,20 @@ means to return the active maps for that window's buffer.  */)
 		}
 	    }
 
-	  /* If on a mode line string with a local keymap,
-	     or for a click on a string, i.e. overlay string or a
-	     string displayed via the `display' property,
-	     consider `local-map' and `keymap' properties of
-	     that string.  */
+	  Lisp_Object pos_area = POSN_POSN (position);
+	  if (EQ (pos_area, Qmode_line) || EQ (pos_area, Qheader_line))
+	    {
+	      /* For clicks on mode line or header line, ignore the maps
+		 we found at POSITION, because properties at point are
+		 not relevant in that case.  */
+	      local_map = Qnil;
+	      keymap = Qnil;
+	    }
+
+	  /* If on a mode line string with a local keymap, or for a
+	     click on a string, i.e. overlay string or a string
+	     displayed via the `display' property, consider only the
+	     `local-map' and `keymap' properties of that string.  */
 
 	  if (CONSP (string) && STRINGP (XCAR (string)))
 	    {
@@ -1749,23 +1758,8 @@ means to return the active maps for that window's buffer.  */)
 		  && XFIXNUM (pos) >= 0
 		  && XFIXNUM (pos) < SCHARS (string))
 		{
-		  Lisp_Object map = Fget_text_property (pos, Qlocal_map,
-							string);
-		  Lisp_Object pos_area = POSN_POSN (position);
-		  /* For clicks on mode line or header line, override
-		     the maps we found at POSITION unconditionally, even
-		     if the corresponding properties of the mode- or
-		     header-line string are nil, because propertries at
-		     point are not relevant in that case.  */
-		  if (!NILP (map)
-		      || EQ (pos_area, Qmode_line)
-		      || EQ (pos_area, Qheader_line))
-		    local_map = map;
-		  map = Fget_text_property (pos, Qkeymap, string);
-		  if (!NILP (map)
-		      || EQ (pos_area, Qmode_line)
-		      || EQ (pos_area, Qheader_line))
-		    keymap = map;
+		  local_map = Fget_text_property (pos, Qlocal_map, string);
+		  keymap = Fget_text_property (pos, Qkeymap, string);
 		}
 	    }
 
diff --git a/test/src/keymap-tests.el b/test/src/keymap-tests.el
index c605c3eb09d..950c741a6dd 100644
--- a/test/src/keymap-tests.el
+++ b/test/src/keymap-tests.el
@@ -509,6 +509,33 @@ g .. h		foo
     ;; From the parent this time/
     (should (equal (keymap-lookup map "u") #'undo))))
 
+(defun keymap-test--maps-for-posn (area string)
+  (current-active-maps
+   nil
+   ;; FIXME: This test would be better if this was a real position
+   ;; created by a real click.
+   `(,(selected-window) ,area (1 . 1) 0 (,string . 0) nil (1 . 1) nil (1 . 1) (1 . 1))))
+
+(ert-deftest keymap-test-keymaps-for-non-buffer-positions ()
+  "`current-active-maps' with non-buffer positions.  (bug#76620)"
+  (with-temp-buffer
+    (pop-to-buffer (current-buffer))
+    (let ((keymap (make-sparse-keymap "keymap-at-point")))
+      (insert (propertize "string" 'keymap keymap))
+      (goto-char (point-min))
+      (should (memq keymap (current-active-maps)))
+      (should-not (memq keymap (keymap-test--maps-for-posn 'mode-line nil)))
+      (should-not (memq keymap (keymap-test--maps-for-posn 'mode-line "s")))
+      (should-not (memq keymap (keymap-test--maps-for-posn nil "s")))
+      (should (memq keymap (keymap-test--maps-for-posn nil nil)))
+      (let* ((mode-line-keymap (make-sparse-keymap "keymap-in-mode-line"))
+             (s (propertize "string" 'keymap mode-line-keymap)))
+        ;; Respect `keymap' in the string clicked on.
+        (should-not (memq keymap (keymap-test--maps-for-posn nil s)))
+        (should-not (memq keymap (keymap-test--maps-for-posn 'mode-line s)))
+        (should (memq mode-line-keymap (keymap-test--maps-for-posn nil s)))
+        (should (memq mode-line-keymap (keymap-test--maps-for-posn 'mode-line s)))))))
+
 (provide 'keymap-tests)
 
 ;;; keymap-tests.el ends here