From 69d748a95e917fd12f4183eb9b0d9b0304fbfcfa Mon Sep 17 00:00:00 2001
From: Stephen Chang <stchang@ccs.neu.edu>
Date: Fri, 26 Jul 2019 12:59:20 -0400
Subject: [PATCH] fix seg fault when using in-X-set sequence constructor with
 wrong kind of set; closes #2765

---
 pkgs/racket-test-core/tests/racket/for.rktl  | 12 ++++++++++++
 racket/collects/racket/private/set-types.rkt | 13 ++++++++++---
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/pkgs/racket-test-core/tests/racket/for.rktl b/pkgs/racket-test-core/tests/racket/for.rktl
index d32578359c..5f293e5682 100644
--- a/pkgs/racket-test-core/tests/racket/for.rktl
+++ b/pkgs/racket-test-core/tests/racket/for.rktl
@@ -776,6 +776,18 @@
 (err/rt-test (for/sum ([x (in-weak-set '(1 2))]) x)
              exn:fail:contract?
              #rx"not a hash set")
+(err/rt-test (for/sum ([x (in-weak-set (set 1 2))]) x)
+             exn:fail:contract?
+             #rx"wrong kind of hash set")
+(err/rt-test (for/sum ([x (in-mutable-set (set 1 2))]) x)
+             exn:fail:contract?
+             #rx"wrong kind of hash set")
+(err/rt-test (for/sum ([x (in-immutable-set (mutable-set 1 2))]) x)
+             exn:fail:contract?
+             #rx"wrong kind of hash set")
+(err/rt-test (for/sum ([x (in-immutable-set (weak-set 1 2))]) x)
+             exn:fail:contract?
+             #rx"wrong kind of hash set")
 (test 10 'in-hash-set (for/sum ([x (in-immutable-set (set 1 2 3 4))]) x))
 (test 10 'in-hash-set (for/sum ([x (in-mutable-set (mutable-set 1 2 3 4))]) x))
 (test 10 'in-hash-set (for/sum ([x (in-weak-set (weak-set 1 2 3 4))]) x))
diff --git a/racket/collects/racket/private/set-types.rkt b/racket/collects/racket/private/set-types.rkt
index 90aef823db..0c568de02e 100644
--- a/racket/collects/racket/private/set-types.rkt
+++ b/racket/collects/racket/private/set-types.rkt
@@ -611,7 +611,7 @@
                    (:do-in
                     ;;outer bindings
                     ([(HT fn) (let ([xs set-expr])
-                                (if (custom-set? xs)
+                                (if (and (custom-set? xs) (-test? xs))
                                     (values
                                      (custom-set-table xs)
                                      (if (custom-set-spec xs)
@@ -619,8 +619,15 @@
                                          (lambda (x) x)))
                                     (values #f #f)))])
                     ;; outer check
-                    (unless (and HT (-test? HT))
-                      (custom-in-set/checked set-expr))
+                    (unless HT
+                      (define s set-expr)
+                      (if (custom-set? s)
+                          (raise (exn:fail:contract
+                                  (format "wrong kind of hash set, expected ~a, got: ~a\n" 'SETTYPE s)
+                                  (current-continuation-marks)))
+                          (raise (exn:fail:contract
+                                  (format "not a hash set: ~a" s)
+                                  (current-continuation-marks)))))
                     ;; loop bindings
                     ([i (-first HT)])
                     ;; pos check