19:30:23 ~/3rd/ocaml> git format-patch trunk --stdout | cat

From 749045d74ec9617e651901fbfe98d135061ec7e5 Mon Sep 17 00:00:00 2001
From: bryant <bryant@defrag.in>
Date: Wed, 7 Oct 2015 19:18:13 +0200
Subject: [PATCH] fix undefined left shift of negative value.

---
 byterun/caml/mlvalues.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/byterun/caml/mlvalues.h b/byterun/caml/mlvalues.h
index 3b94d01..025bee1 100644
--- a/byterun/caml/mlvalues.h
+++ b/byterun/caml/mlvalues.h
@@ -68,7 +68,7 @@ typedef uintnat mark_t;
 
 /* Conversion macro names are always of the form  "to_from". */
 /* Example: Val_long as in "Val from long" or "Val of long". */
-#define Val_long(x)     (((intnat)(x) << 1) + 1)
+#define Val_long(x)     ((intnat) (((uintnat)(x) << 1)) + 1)
 #define Long_val(x)     ((x) >> 1)
 #define Max_long (((intnat)1 << (8 * sizeof(value) - 2)) - 1)
 #define Min_long (-((intnat)1 << (8 * sizeof(value) - 2)))
-- 
1.7.10.4

If E1 has a signed
type and nonnegative value, and E1 × 2 E2 is representable in the result type, then that is
the resulting value; otherwise, the behavior is undefined.