From a7038173aa7e926b721d9fc06ec21fbcd41bd6e8 Mon Sep 17 00:00:00 2001
From: Cameron Moy <mail@camoy.name>
Date: Sat, 21 Nov 2020 03:48:41 -0500
Subject: [PATCH] fix contract on `impersonate-async-channel`

---
 .../tests/racket/async-channel.rktl           | 35 ++++++++++++++++++-
 racket/collects/racket/async-channel.rkt      |  2 +-
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/pkgs/racket-test-core/tests/racket/async-channel.rktl b/pkgs/racket-test-core/tests/racket/async-channel.rktl
index 2bbbbedf92..b651de3e41 100644
--- a/pkgs/racket-test-core/tests/racket/async-channel.rktl
+++ b/pkgs/racket-test-core/tests/racket/async-channel.rktl
@@ -89,5 +89,38 @@
 (check-limited 1)
 (check-limited 3)
 
-(report-errs)
+;; async channel chaperone and impersonator
 
+(let ()
+  (define (record ch c-or-i go)
+    (define trace '())
+    (define (add-to-trace ele) (set! trace (cons ele trace)))
+    (go (c-or-i ch
+                (λ (ele) (add-to-trace (list 'get ele)) ele)
+                (λ (ele) (add-to-trace (list 'put ele)) ele)))
+    (reverse trace))
+
+  (define (test-chaperone/impersonator c-or-i)
+    (test '((put 1) (put 2) (get 1) (get 2))
+          record
+          (make-async-channel)
+          c-or-i
+          (λ (ch)
+            (async-channel-put ch 1)
+            (async-channel-put ch 2)
+            (async-channel-get ch)
+            (async-channel-get ch)))
+    (test '((put 1) (get 1) (put 2) (get 2))
+          record
+          (make-async-channel)
+          c-or-i
+          (λ (ch)
+            (async-channel-put ch 1)
+            (async-channel-get ch)
+            (async-channel-put ch 2)
+            (async-channel-get ch))))
+
+  (test-chaperone/impersonator chaperone-async-channel)
+  (test-chaperone/impersonator impersonate-async-channel))
+
+(report-errs)
diff --git a/racket/collects/racket/async-channel.rkt b/racket/collects/racket/async-channel.rkt
index a8b767d47a..616e1f19ab 100644
--- a/racket/collects/racket/async-channel.rkt
+++ b/racket/collects/racket/async-channel.rkt
@@ -273,7 +273,7 @@
                                                (any/c . -> . any/c)
                                                (any/c . -> . any/c))
                                               #:rest (listof any/c)
-                                              . ->* . (and/c chaperone? async-channel?)))
+                                              . ->* . (and/c impersonator? async-channel?)))
                   (chaperone-async-channel ((async-channel?
                                              (any/c . -> . any/c)
                                              (any/c . -> . any/c))