From a0437ed2068f222afff26dd8ad6da989c70116d5 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Sat, 18 Nov 2006 23:34:52 +0000
Subject: [PATCH] fix call_ec so that it works when used outside of Scheme
 evaluation, such as when raise_break is called to handle a ctl-c in MrEd

svn: r4885
---
 src/mzscheme/src/fun.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/mzscheme/src/fun.c b/src/mzscheme/src/fun.c
index ea963a8791..3e5a8927fa 100644
--- a/src/mzscheme/src/fun.c
+++ b/src/mzscheme/src/fun.c
@@ -3281,7 +3281,9 @@ scheme_call_ec (int argc, Scheme_Object *argv[])
 
   scheme_save_env_stack_w_thread(cont->envss, p1);
 
-  p1->barrier_prompt->is_captured = 1;
+  if (p1->barrier_prompt) /* can be NULL if this is for raise_break()
+                             called outside any Scheme evaluation */
+    p1->barrier_prompt->is_captured = 1;
 
   scheme_push_continuation_frame(&cframe);
   scheme_set_cont_mark((Scheme_Object *)cont, scheme_true);