From ac428f89fa09a8325041589a251323fb9ed42d16 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Fri, 1 Aug 2014 10:52:27 +0100
Subject: [PATCH] use-before-definition analysis: fix checking of
 `with-cont-mark` form

Similar to the `set!` problem.
---
 .../racket-test/tests/racket/letrec.rktl      | 22 +++++++++++++++++++
 racket/src/racket/src/letrec_check.c          | 10 +++++++--
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/pkgs/racket-pkgs/racket-test/tests/racket/letrec.rktl b/pkgs/racket-pkgs/racket-test/tests/racket/letrec.rktl
index b33f0cf248..b11023c051 100644
--- a/pkgs/racket-pkgs/racket-test/tests/racket/letrec.rktl
+++ b/pkgs/racket-pkgs/racket-test/tests/racket/letrec.rktl
@@ -127,5 +127,27 @@
    b)
  letrec-exn?)
 
+(err/rt-test
+ (letrec ([b (with-continuation-mark
+                 'x
+                 (lambda () c)
+               ((continuation-mark-set-first
+                 (current-continuation-marks)
+                 'x)))]
+          [c 1])
+   c)
+ letrec-exn?)
+
+(err/rt-test
+ (letrec ([b (with-continuation-mark
+                 'x
+                 (lambda () c)
+               (+ (random)
+                  ((continuation-mark-set-first
+                    (current-continuation-marks)
+                    'x))))]
+          [c 1])
+   c)
+ letrec-exn?)
 
 (report-errs)
diff --git a/racket/src/racket/src/letrec_check.c b/racket/src/racket/src/letrec_check.c
index b9b5433f7d..cd08651983 100644
--- a/racket/src/racket/src/letrec_check.c
+++ b/racket/src/racket/src/letrec_check.c
@@ -738,14 +738,20 @@ static Scheme_Object *letrec_check_wcm(Scheme_Object *o, Letrec_Check_Frame *fra
                                        Scheme_Object *uvars, Scheme_Object *pvars, Scheme_Object *pos)
 {
   Scheme_With_Continuation_Mark *wcm;
-  Scheme_Object *val;
+  Scheme_Object *val, *val_uvars, *val_pvars, *val_pos;
 
   wcm = (Scheme_With_Continuation_Mark *)o;
     
   val = letrec_check_expr(wcm->key, frame, uvars, pvars, pos);
   wcm->key = val;
-  val = letrec_check_expr(wcm->val, frame, uvars, pvars, pos);
+
+  /* Since a value can be accessed through `current-continuaton-marks`... */
+  val_uvars = merge_vars(uvars, pvars);
+  val_pvars = rem_vars(pvars);
+  val_pos = scheme_false;
+  val = letrec_check_expr(wcm->val, frame, val_uvars, val_pvars, val_pos);
   wcm->val = val;
+
   val = letrec_check_expr(wcm->body, frame, uvars, pvars, pos);
   wcm->body = val;