=== modified file 'src/alloc.c'
--- src/alloc.c	2012-06-28 19:09:41 +0000
+++ src/alloc.c	2012-06-29 06:53:41 +0000
@@ -4608,7 +4608,7 @@
 
 static void
 mark_memory (void *start, void *end)
-#ifdef __clang__
+#if defined (__clang__) && defined (__has_feature) && __has_feature(address_sanitizer)
   /* Do not allow -faddress-sanitizer to check this function, since it
      crosses the function stack boundary, and thus would yield many
      false positives. */