From e22e9279b5f065376e576c90c6080dacafeaff34 Mon Sep 17 00:00:00 2001
From: sof <unknown>
Date: Tue, 23 Jul 2002 18:50:54 +0000
Subject: [PATCH] [project @ 2002-07-23 18:50:54 by sof] gmtoff: MS CRT
 implementation of _tzset() (and _timezone) assumes that >0
 represent positions west of the Prime Meridian. This module
 assumes the opposite, so flip the sign of 'timezone' when
 compiling for mingw.

---
 System/Time.hsc |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/System/Time.hsc b/System/Time.hsc
index 6d8a800..3df3091 100644
--- a/System/Time.hsc
+++ b/System/Time.hsc
@@ -348,6 +348,12 @@ foreign import ccall unsafe "timezone" timezone :: Ptr CLong
 gmtoff x = do 
   dst <- (#peek struct tm,tm_isdst) x
   tz  <- peek timezone
+#if defined(mingw32_TARGET_OS)
+   -- According to the MSVC documentation for _tzset, _timezone is > 0
+   -- for locations west of the Prime Meridian. Code elsewhere in this
+   -- module assume that >0 gmt offsets means east, so flip the sign.
+  tz  <- return (-tz)
+#endif
   if dst then return (fromIntegral tz - 3600) else return tz
 # endif /* ! HAVE_ALTZONE */
 #endif  /* ! HAVE_TM_ZONE */
-- 
1.7.10.4