From a3a5a4e2e26e23d6fb5988181af34bbf341e248b Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Tue, 16 Jul 2013 14:29:34 -0600
Subject: [PATCH] fix GC bug in FFI

Replicate e3eed89 for v5.3.6.
---
 src/foreign/foreign.c    | 5 +++++
 src/foreign/foreign.rktc | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/src/foreign/foreign.c b/src/foreign/foreign.c
index 8e75e53f8e..678bd2f4c6 100644
--- a/src/foreign/foreign.c
+++ b/src/foreign/foreign.c
@@ -3219,6 +3219,11 @@ Scheme_Object *ffi_do_call(int argc, Scheme_Object *argv[], Scheme_Object *self)
                     nargs, ivals, avalues,
                     offsets, p);
 
+  /* Use `data' to make sure it's kept alive (as far as the GC is concerned)
+     until the foreign call returns: */
+  if ((void*)data == (void*)scheme_true)
+    scheme_signal_error("dummy test suceeded!?");
+
   if (save_errno != 0) save_errno_values(save_errno);
   ivals = NULL; /* no need now to hold on to this */
   for (i=0; i<nargs; i++) { avalues[i] = NULL; } /* no need for these refs */
diff --git a/src/foreign/foreign.rktc b/src/foreign/foreign.rktc
index 0d5333adfc..06b3edfedd 100755
--- a/src/foreign/foreign.rktc
+++ b/src/foreign/foreign.rktc
@@ -2548,6 +2548,11 @@ Scheme_Object *ffi_do_call(int argc, Scheme_Object *argv[], Scheme_Object *self)
                     nargs, ivals, avalues, 
                     offsets, p);
 
+  /* Use `data' to make sure it's kept alive (as far as the GC is concerned)
+     until the foreign call returns: */
+  if ((void*)data == (void*)scheme_true)
+    scheme_signal_error("dummy test suceeded!?");
+
   if (save_errno != 0) save_errno_values(save_errno);
   ivals = NULL; /* no need now to hold on to this */
   for (i=0; i<nargs; i++) { avalues[i] = NULL; } /* no need for these refs */