From 07f567fcb3750fe3902679d160c080b2fd551a2e Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Sun, 27 Jun 2010 08:59:58 -0600
Subject: [PATCH] fix arity handlign and reporting for chaperoned procedures

---
 src/racket/src/fun.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/racket/src/fun.c b/src/racket/src/fun.c
index 45a76a5e4d..f84fdc2f1e 100644
--- a/src/racket/src/fun.c
+++ b/src/racket/src/fun.c
@@ -4142,6 +4142,18 @@ Scheme_Object *scheme_apply_chaperone(Scheme_Object *o, int argc, Scheme_Object
     }
   }
 
+  /* Ensure that the original procedure accepts `argc' arguments: */
+  a[0] = px->prev;
+  if (!scheme_check_proc_arity(NULL, argc, 0, 0, a)) {
+    /* Apply the original procedure, in case the chaperone would accept
+       `argc' arguments (in addition to the original procedure's arity)
+       in case the methodness of the original procedure is different
+       from the chaperone, or in case the procedures have different names. */
+    (void)_scheme_apply_multi(px->prev, argc, argv);
+    scheme_signal_error("internal error: unexpected success applying chaperoned procedure");
+    return NULL;
+  }
+
   v = _scheme_apply_multi(px->redirects, argc, argv);
   if (v == SCHEME_MULTIPLE_VALUES) {
     GC_CAN_IGNORE Scheme_Thread *p = scheme_current_thread;