(Fdefine_key): Improve error message when KEY begins with a non-prefix key.

[gnu-emacs] / src / keymap.c

diff --git a/src/keymap.c b/src/keymap.c
index 66f17178d5bd564fd4c81592a7a2f41b537a6eed..4f8343bf5cfe0a8589c9c3a2d840b19cbfaf5db0 100644 (file)
--- a/src/keymap.c
+++ b/src/keymap.c
@@ -1193,8 +1193,11 @@ binding KEY to DEF is added at the front of KEYMAP.  */)
       if (!CONSP (keymap))
        /* We must use Fkey_description rather than just passing key to
           error; key might be a vector, not a string.  */
-       error ("Key sequence %s uses invalid prefix characters",
-              SDATA (Fkey_description (key, Qnil)));
+       error ("Key sequence %s starts with non-prefix key %s",
+              SDATA (Fkey_description (key, Qnil)),
+              SDATA (Fkey_description (Fsubstring (key, make_number (0),
+                                                   make_number (idx)),
+                                       Qnil)));
     }
 }