emacs-29 39035fbfc5f: Avoid crashes in 'describe-keymap' due to shadowing

[Eli Zaretskii]

branch: emacs-29
commit 39035fbfc5f6dfa66c9ba14f61a8d1c751d847c0
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Avoid crashes in 'describe-keymap' due to shadowing
    
    * src/keymap.c (describe_vector): Handle shadowing by something
    other than a symbol.  (Bug#62867)
---
 src/keymap.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/src/keymap.c b/src/keymap.c
index efac410d317..7f5777c9251 100644
--- a/src/keymap.c
+++ b/src/keymap.c
@@ -3308,13 +3308,18 @@ describe_vector (Lisp_Object vector, Lisp_Object 
prefix, Lisp_Object args,
       if (this_shadowed)
        {
          SET_PT (PT - 1);
-         static char const fmt[] = "  (currently shadowed by `%s')";
-         USE_SAFE_ALLOCA;
-         char *buffer = SAFE_ALLOCA (sizeof fmt +
-                                     SBYTES (SYMBOL_NAME (shadowed_by)));
-         esprintf (buffer, fmt, SDATA (SYMBOL_NAME (shadowed_by)));
-         insert_string (buffer);
-         SAFE_FREE();
+         if (SYMBOLP (shadowed_by))
+           {
+             static char const fmt[] = "  (currently shadowed by `%s')";
+             USE_SAFE_ALLOCA;
+             char *buffer =
+               SAFE_ALLOCA (sizeof fmt + SBYTES (SYMBOL_NAME (shadowed_by)));
+             esprintf (buffer, fmt, SDATA (SYMBOL_NAME (shadowed_by)));
+             insert_string (buffer);
+             SAFE_FREE();
+           }
+         else  /* Could be a keymap, a lambda, or a keyboard macro.  */
+           insert_string ("  (currently shadowed)");
          SET_PT (PT + 1);
        }
     }