From cc487a4d9abd333f704b83fae93e9c377b73f559 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Wed, 15 May 2019 10:41:43 -0600
Subject: [PATCH] cs: fix incorrect impersonator discard in `chaperone-of?`

---
 pkgs/racket-test-core/tests/racket/chaperone.rktl | 9 +++++++++
 racket/src/cs/rumble/equal.ss                     | 3 +--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/pkgs/racket-test-core/tests/racket/chaperone.rktl b/pkgs/racket-test-core/tests/racket/chaperone.rktl
index 124967bd76..46ca4821d5 100644
--- a/pkgs/racket-test-core/tests/racket/chaperone.rktl
+++ b/pkgs/racket-test-core/tests/racket/chaperone.rktl
@@ -196,6 +196,15 @@
    (test (void) vector-set! b2 1 'fine)
    (test 'fine vector-ref b 1)))
 
+;; impersonator-of does not imply chaperone-of
+(let ()
+  (define vec1 (vector 1 2 3))
+  (define vec2 (impersonate-vector vec1 (lambda (v i x) x) (lambda (v i x) x)))
+  (test #t impersonator-of? vec2 vec1)
+  (test #f chaperone-of? vec2 vec1)
+  (test #f impersonator-of? vec1 vec2)
+  (test #f chaperone-of? vec1 vec2))
+
 ;; test chaperone-of checks in a chaperone:
 (let ([b (vector 0)])
   (let ([b2 (chaperone-vector b 
diff --git a/racket/src/cs/rumble/equal.ss b/racket/src/cs/rumble/equal.ss
index f1d11b068a..46c3905901 100644
--- a/racket/src/cs/rumble/equal.ss
+++ b/racket/src/cs/rumble/equal.ss
@@ -42,8 +42,7 @@
                          (let ([ctx (deeper-context ctx)])
                            (equal? a2 b ctx)))]
                  [else #f]))]
-             [(and (eq? mode 'chaperone-of?)
-                   (chaperone? b))
+             [(eq? mode 'chaperone-of?)
               ;; `a` does not include `b`, so give up
               #f]
              [else