bug#62207: 29.0.60; Trying to remove non-existent key binding instead adds a binding

[Robert Pluim <rpluim@gmail.com>]

>>>>> On Wed, 15 Mar 2023 17:51:27 +0100, Jonas Bernoulli <jonas@bernoul.li> said:

    Jonas> As a side-note, it would be nice if it were possible to lookup a
    Jonas> key in a keymap only, while ignoring bindings in its parent keymap.

A feature request and a bug report? Tsk ;-) Luckily the infrastructure
is actually there already.

The following passes my admittedly quick testing for both.

diff --git c/lisp/keymap.el i/lisp/keymap.el
index 4f02639ffe2..706da70d360 100644
--- c/lisp/keymap.el
+++ i/lisp/keymap.el
@@ -370,7 +370,7 @@ key-translate
 	    (make-char-table 'keyboard-translate-table nil)))
   (aset keyboard-translate-table (key-parse from) (key-parse to)))
 
-(defun keymap-lookup (keymap key &optional accept-default no-remap position)
+(defun keymap-lookup (keymap key &optional accept-default no-remap position noparent)
   "Return the binding for command KEY in KEYMAP.
 KEY is a string that satisfies `key-valid-p'.
 
@@ -406,8 +406,10 @@ keymap-lookup
   (keymap--check key)
   (when (and keymap position)
     (error "Can't pass in both keymap and position"))
+  (when (and (not keymap) noparent)
+    (error "Must specify keymap when noparent is t"))
   (if keymap
-      (let ((value (lookup-key keymap (key-parse key) accept-default)))
+      (let ((value (lookup-key keymap (key-parse key) accept-default noparent)))
         (if (and (not no-remap)
                    (symbolp value))
             (or (command-remapping value) value)
diff --git c/src/keymap.c i/src/keymap.c
index 23453eaa9a6..a660a687994 100644
--- c/src/keymap.c
+++ i/src/keymap.c
@@ -887,22 +887,23 @@ store_in_keymap (Lisp_Object keymap, register Lisp_Object idx,
   keymap_end:
     /* We have scanned the entire keymap, and not found a binding for
        IDX.  Let's add one.  */
-    {
-      Lisp_Object elt;
+    if (!remove)
+      {
+	Lisp_Object elt;
 
-      if (CONSP (idx) && CHARACTERP (XCAR (idx)))
-	{
-	  /* IDX specifies a range of characters, and not all of them
-	     were handled yet, which means this keymap doesn't have a
-	     char-table.  So, we insert a char-table now.  */
-	  elt = Fmake_char_table (Qkeymap, Qnil);
-	  Fset_char_table_range (elt, idx, NILP (def) ? Qt : def);
-	}
-      else
-	elt = Fcons (idx, def);
-      CHECK_IMPURE (insertion_point, XCONS (insertion_point));
-      XSETCDR (insertion_point, Fcons (elt, XCDR (insertion_point)));
-    }
+	if (CONSP (idx) && CHARACTERP (XCAR (idx)))
+	  {
+	    /* IDX specifies a range of characters, and not all of them
+	       were handled yet, which means this keymap doesn't have a
+	       char-table.  So, we insert a char-table now.  */
+	    elt = Fmake_char_table (Qkeymap, Qnil);
+	    Fset_char_table_range (elt, idx, NILP (def) ? Qt : def);
+	  }
+	else
+	  elt = Fcons (idx, def);
+	CHECK_IMPURE (insertion_point, XCONS (insertion_point));
+	XSETCDR (insertion_point, Fcons (elt, XCDR (insertion_point)));
+      }
   }
 
   return def;
@@ -1240,14 +1241,15 @@ DEFUN ("command-remapping", Fcommand_remapping, Scommand_remapping, 1, 3, 0,
   if (NILP (keymaps))
     command = Fkey_binding (command_remapping_vector, Qnil, Qt, position);
   else
-    command = Flookup_key (keymaps, command_remapping_vector, Qnil);
+    command = Flookup_key (keymaps, command_remapping_vector, Qnil, Qnil);
   return FIXNUMP (command) ? Qnil : command;
 }
 
 static Lisp_Object
-lookup_key_1 (Lisp_Object keymap, Lisp_Object key, Lisp_Object accept_default)
+lookup_key_1 (Lisp_Object keymap, Lisp_Object key, Lisp_Object accept_default, Lisp_Object noparent)
 {
   bool t_ok = !NILP (accept_default);
+  bool noinherit = !NILP (noparent);
 
   if (!CONSP (keymap) && !NILP (keymap))
     keymap = get_keymap (keymap, true, true);
@@ -1275,7 +1277,7 @@ lookup_key_1 (Lisp_Object keymap, Lisp_Object key, Lisp_Object accept_default)
       if (!FIXNUMP (c) && !SYMBOLP (c) && !CONSP (c) && !STRINGP (c))
 	message_with_string ("Key sequence contains invalid event %s", c, 1);
 
-      Lisp_Object cmd = access_keymap (keymap, c, t_ok, 0, 1);
+      Lisp_Object cmd = access_keymap (keymap, c, t_ok, noinherit, 1);
       if (idx == length)
 	return cmd;
 
@@ -1290,7 +1292,7 @@ lookup_key_1 (Lisp_Object keymap, Lisp_Object key, Lisp_Object accept_default)
 /* Value is number if KEY is too long; nil if valid but has no definition.  */
 /* GC is possible in this function.  */
 
-DEFUN ("lookup-key", Flookup_key, Slookup_key, 2, 3, 0,
+DEFUN ("lookup-key", Flookup_key, Slookup_key, 2, 4, 0,
        doc: /* Look up key sequence KEY in KEYMAP.  Return the definition.
 This is a legacy function; see `keymap-lookup' for the recommended
 function to use instead.
@@ -1310,9 +1312,9 @@ DEFUN ("lookup-key", Flookup_key, Slookup_key, 2, 3, 0,
 usable as a general function for probing keymaps.  However, if the
 third optional argument ACCEPT-DEFAULT is non-nil, `lookup-key' will
 recognize the default bindings, just as `read-key-sequence' does.  */)
-  (Lisp_Object keymap, Lisp_Object key, Lisp_Object accept_default)
+  (Lisp_Object keymap, Lisp_Object key, Lisp_Object accept_default, Lisp_Object noparent)
 {
-  Lisp_Object found = lookup_key_1 (keymap, key, accept_default);
+  Lisp_Object found = lookup_key_1 (keymap, key, accept_default, noparent);
   if (!NILP (found) && !NUMBERP (found))
     return found;
 
@@ -1390,7 +1392,7 @@ DEFUN ("lookup-key", Flookup_key, Slookup_key, 2, 3, 0,
 	}
 
       /* Check for match.  */
-      found = lookup_key_1 (keymap, new_key, accept_default);
+      found = lookup_key_1 (keymap, new_key, accept_default, noparent);
       if (!NILP (found) && !NUMBERP (found))
 	break;
 
@@ -1432,7 +1434,7 @@ DEFUN ("lookup-key", Flookup_key, Slookup_key, 2, 3, 0,
 	}
 
       /* Check for match.  */
-      found = lookup_key_1 (keymap, new_key, accept_default);
+      found = lookup_key_1 (keymap, new_key, accept_default, noparent);
       if (!NILP (found) && !NUMBERP (found))
 	break;
     }
@@ -1823,7 +1825,7 @@ DEFUN ("key-binding", Fkey_binding, Skey_binding, 1, 4, 0,
     }
 
   Lisp_Object value = Flookup_key (Fcurrent_active_maps (Qt, position),
-				   key, accept_default);
+				   key, accept_default, Qnil);
 
   if (NILP (value) || FIXNUMP (value))
     return Qnil;
@@ -1864,7 +1866,7 @@ DEFUN ("minor-mode-key-binding", Fminor_mode_key_binding, Sminor_mode_key_bindin
   int j;
   for (int i = j = 0; i < nmaps; i++)
     if (!NILP (maps[i])
-	&& !NILP (binding = Flookup_key (maps[i], key, accept_default))
+	&& !NILP (binding = Flookup_key (maps[i], key, accept_default, Qnil))
 	&& !FIXNUMP (binding))
       {
 	if (KEYMAPP (binding))
@@ -2013,7 +2015,7 @@ DEFUN ("accessible-keymaps", Faccessible_keymaps, Saccessible_keymaps,
     {
       /* If a prefix was specified, start with the keymap (if any) for
 	 that prefix, so we don't waste time considering other prefixes.  */
-      Lisp_Object tem = Flookup_key (keymap, prefix, Qt);
+      Lisp_Object tem = Flookup_key (keymap, prefix, Qt, Qnil);
       /* Flookup_key may give us nil, or a number,
 	 if the prefix is not defined in this particular map.
 	 It might even give us a list that isn't a keymap.  */
@@ -2453,7 +2455,7 @@ preferred_sequence_p (Lisp_Object seq)
 shadow_lookup (Lisp_Object keymap, Lisp_Object key, Lisp_Object accept_default,
 	       bool remap)
 {
-  Lisp_Object value = Flookup_key (keymap, key, accept_default);
+  Lisp_Object value = Flookup_key (keymap, key, accept_default, Qnil);
 
   if (FIXNATP (value))          /* `key' is too long!  */
     return Qnil;
@@ -3237,7 +3239,7 @@ describe_vector (Lisp_Object vector, Lisp_Object prefix, Lisp_Object args,
 	 one in the same keymap.  */
       if (!NILP (entire_map))
 	{
-	  Lisp_Object tem = Flookup_key (entire_map, kludge, Qt);
+	  Lisp_Object tem = Flookup_key (entire_map, kludge, Qt, Qnil);
 
 	  if (!EQ (tem, definition))
 	    continue;