From 53ef242889f11554470a11f7c97a565136678e5a Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Wed, 30 Sep 2020 07:14:24 -0600
Subject: [PATCH] fix arity exception for a keyword procedure

Closes #3416
---
 pkgs/racket-test-core/tests/racket/procs.rktl | 10 ++++++++++
 racket/collects/racket/private/kw.rkt         |  2 +-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/pkgs/racket-test-core/tests/racket/procs.rktl b/pkgs/racket-test-core/tests/racket/procs.rktl
index e28f31aea6..8f56cf64bb 100644
--- a/pkgs/racket-test-core/tests/racket/procs.rktl
+++ b/pkgs/racket-test-core/tests/racket/procs.rktl
@@ -773,6 +773,16 @@
   (test (list the-a the-b) the-b)
   (test 0 procedure-arity the-b))
 
+;; ----------------------------------------
+;; Make sure wrong number with keywords is an arity exception:
+
+(let ()
+  (define (hello a b #:key key) (display a))
+  (test #t
+        exn:fail:contract:arity?
+        (with-handlers ([values values])
+          (hello 1 #:key 'hi))))
+
 ;; ----------------------------------------
 
 (report-errs)
diff --git a/racket/collects/racket/private/kw.rkt b/racket/collects/racket/private/kw.rkt
index 555b5dcfd9..0ebc8257ea 100644
--- a/racket/collects/racket/private/kw.rkt
+++ b/racket/collects/racket/private/kw.rkt
@@ -1578,7 +1578,7 @@
                                             (object-name p)
                                             p))])
                   (raise
-                   (exn:fail:contract
+                   ((if (or extra-kw missing-kw) exn:fail:contract exn:fail:contract:arity)
                     (if extra-kw
                         (if (keyword-procedure? p)
                             (format