From 990555cd8dee2597b7a77ef743765161558df1b7 Mon Sep 17 00:00:00 2001
From: Robby Findler <robby@racket-lang.org>
Date: Fri, 26 Feb 2016 08:05:32 -0600
Subject: [PATCH] fix arity checking for -> contract with ellipses

closes #1266
---
 pkgs/racket-test/tests/racket/contract/arrow.rkt      |  5 +++++
 .../racket/contract/private/arity-checking.rkt        | 11 ++++++++---
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/pkgs/racket-test/tests/racket/contract/arrow.rkt b/pkgs/racket-test/tests/racket/contract/arrow.rkt
index 957f936f1a..b5d5ce0a99 100644
--- a/pkgs/racket-test/tests/racket/contract/arrow.rkt
+++ b/pkgs/racket-test/tests/racket/contract/arrow.rkt
@@ -367,6 +367,11 @@
                (λ args args)
                'pos 'neg)
      1 2 3 4 #f 6 7))
+  (test/spec-passed
+   'contract->...5
+   '(contract (-> procedure? any/c ... list? any)
+              (λ (proc last . stuff) stuff)
+              'pos 'neg))
 
   
   (test/spec-passed
diff --git a/racket/collects/racket/contract/private/arity-checking.rkt b/racket/collects/racket/contract/private/arity-checking.rkt
index 7f3bb9d7b7..065be9c940 100644
--- a/racket/collects/racket/contract/private/arity-checking.rkt
+++ b/racket/collects/racket/contract/private/arity-checking.rkt
@@ -1,6 +1,7 @@
 #lang racket/base
 (require "blame.rkt"
-         "kwd-info-struct.rkt")
+         "kwd-info-struct.rkt"
+         "list.rkt")
 
 (provide do-arity-checking
          
@@ -24,7 +25,11 @@
      (define arity (if (list? (procedure-arity val))
                        (procedure-arity val)
                        (list (procedure-arity val))))
-     (define expected-number-of-non-keyword-args (length ->stct-doms))
+    
+     (define exra-required-args (if (ellipsis-rest-arg-ctc? ->stct-rest)
+                                    (length (*list-ctc-suffix ->stct-rest))
+                                    0))
+     (define expected-number-of-non-keyword-args (+ (length ->stct-doms) exra-required-args))
      (define matching-arity?
        (and (for/or ([a (in-list arity)])
               (or (equal? expected-number-of-non-keyword-args a)
@@ -33,7 +38,7 @@
             (if ->stct-rest
                 (let ([lst (car (reverse arity))])
                   (and (arity-at-least? lst)
-                       (<= (arity-at-least-value lst) ->stct-min-arity)))
+                       (<= (arity-at-least-value lst) (+ exra-required-args ->stct-min-arity))))
                 #t)))
      (unless matching-arity?
        (k