Original report: https://bugs.gentoo.org/show_bug.cgi?id=305853
new ghc hates old '-ffi' style flags:
> Data/Time/Clock/CTimeval.hs:1:11:
>     Warning: -ffi is deprecated: use -XForeignFunctionInterface or pragma {-# LANGUAGE ForeignFunctionInterface #-} instead
> <no location info>:
> Failing due to -Werror.
diff --git a/Data/Time.hs b/Data/Time.hs
index 4167ec6..e55f25a 100644
--- a/Data/Time.hs
+++ b/Data/Time.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 module Data.Time
 (
diff --git a/Data/Time/Calendar.hs b/Data/Time/Calendar.hs
index 30dd9bf..9d6cf1a 100644
--- a/Data/Time/Calendar.hs
+++ b/Data/Time/Calendar.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 module Data.Time.Calendar
 (
diff --git a/Data/Time/Calendar/Days.hs b/Data/Time/Calendar/Days.hs
index 4b563bf..8816e80 100644
--- a/Data/Time/Calendar/Days.hs
+++ b/Data/Time/Calendar/Days.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- #hide
 module Data.Time.Calendar.Days
diff --git a/Data/Time/Calendar/Easter.hs b/Data/Time/Calendar/Easter.hs
index 66283d2..dd45363 100644
--- a/Data/Time/Calendar/Easter.hs
+++ b/Data/Time/Calendar/Easter.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 module Data.Time.Calendar.Easter
 	(
diff --git a/Data/Time/Calendar/Gregorian.hs b/Data/Time/Calendar/Gregorian.hs
index 2d3546c..52a7c43 100644
--- a/Data/Time/Calendar/Gregorian.hs
+++ b/Data/Time/Calendar/Gregorian.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- #hide
 module Data.Time.Calendar.Gregorian
diff --git a/Data/Time/Calendar/Julian.hs b/Data/Time/Calendar/Julian.hs
index 5b389fb..7c2ede4 100644
--- a/Data/Time/Calendar/Julian.hs
+++ b/Data/Time/Calendar/Julian.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 module Data.Time.Calendar.Julian
 (
diff --git a/Data/Time/Calendar/JulianYearDay.hs b/Data/Time/Calendar/JulianYearDay.hs
index ba10c8f..c7f38ae 100644
--- a/Data/Time/Calendar/JulianYearDay.hs
+++ b/Data/Time/Calendar/JulianYearDay.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- #hide
 module Data.Time.Calendar.JulianYearDay
diff --git a/Data/Time/Calendar/MonthDay.hs b/Data/Time/Calendar/MonthDay.hs
index ac0c4d3..f823cae 100644
--- a/Data/Time/Calendar/MonthDay.hs
+++ b/Data/Time/Calendar/MonthDay.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 module Data.Time.Calendar.MonthDay
 	(
diff --git a/Data/Time/Calendar/OrdinalDate.hs b/Data/Time/Calendar/OrdinalDate.hs
index 9dbdd96..139fbd3 100644
--- a/Data/Time/Calendar/OrdinalDate.hs
+++ b/Data/Time/Calendar/OrdinalDate.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- | ISO 8601 Ordinal Date format
 module Data.Time.Calendar.OrdinalDate where
diff --git a/Data/Time/Calendar/Private.hs b/Data/Time/Calendar/Private.hs
index f57599c..b9a6af1 100644
--- a/Data/Time/Calendar/Private.hs
+++ b/Data/Time/Calendar/Private.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- #hide
 module Data.Time.Calendar.Private where
diff --git a/Data/Time/Calendar/WeekDate.hs b/Data/Time/Calendar/WeekDate.hs
index 0568a32..8399cb1 100644
--- a/Data/Time/Calendar/WeekDate.hs
+++ b/Data/Time/Calendar/WeekDate.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- | ISO 8601 Week Date format
 module Data.Time.Calendar.WeekDate where
diff --git a/Data/Time/Clock.hs b/Data/Time/Clock.hs
index 5adcaaa..ec10d6e 100644
--- a/Data/Time/Clock.hs
+++ b/Data/Time/Clock.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- | Types and functions for UTC and UT1
 module Data.Time.Clock
diff --git a/Data/Time/Clock/CTimeval.hs b/Data/Time/Clock/CTimeval.hs
index 8025bdb..bc03f2f 100644
--- a/Data/Time/Clock/CTimeval.hs
+++ b/Data/Time/Clock/CTimeval.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -ffi -Wall -Werror -cpp #-}
+{-# OPTIONS -ffi -Wall -cpp #-}
 
 -- #hide
 module Data.Time.Clock.CTimeval where
diff --git a/Data/Time/Clock/POSIX.hs b/Data/Time/Clock/POSIX.hs
index b877bf7..1809792 100644
--- a/Data/Time/Clock/POSIX.hs
+++ b/Data/Time/Clock/POSIX.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror -cpp #-}
+{-# OPTIONS -Wall -cpp #-}
 
 -- | POSIX time, if you need to deal with timestamps and the like.
 -- Most people won't need this module.
diff --git a/Data/Time/Clock/Scale.hs b/Data/Time/Clock/Scale.hs
index 053c515..5fe3fff 100644
--- a/Data/Time/Clock/Scale.hs
+++ b/Data/Time/Clock/Scale.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- #hide
 module Data.Time.Clock.Scale
diff --git a/Data/Time/Clock/TAI.hs b/Data/Time/Clock/TAI.hs
index b1c37c1..f03efeb 100644
--- a/Data/Time/Clock/TAI.hs
+++ b/Data/Time/Clock/TAI.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- | TAI and leap-second tables for converting to UTC: most people won't need this module.
 module Data.Time.Clock.TAI
diff --git a/Data/Time/Clock/UTC.hs b/Data/Time/Clock/UTC.hs
index 57daa6b..9b2a701 100644
--- a/Data/Time/Clock/UTC.hs
+++ b/Data/Time/Clock/UTC.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- #hide
 module Data.Time.Clock.UTC
diff --git a/Data/Time/Clock/UTCDiff.hs b/Data/Time/Clock/UTCDiff.hs
index 66a2a48..6e1d912 100644
--- a/Data/Time/Clock/UTCDiff.hs
+++ b/Data/Time/Clock/UTCDiff.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- #hide
 module Data.Time.Clock.UTCDiff where
diff --git a/Data/Time/Format.hs b/Data/Time/Format.hs
index 5e10cd1..0c4fe59 100644
--- a/Data/Time/Format.hs
+++ b/Data/Time/Format.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 module Data.Time.Format
 	(
diff --git a/Data/Time/Format/Parse.hs b/Data/Time/Format/Parse.hs
index c4a258d..37055cb 100644
--- a/Data/Time/Format/Parse.hs
+++ b/Data/Time/Format/Parse.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- #hide
 module Data.Time.Format.Parse 
diff --git a/Data/Time/LocalTime.hs b/Data/Time/LocalTime.hs
index 5676b58..9ddf942 100644
--- a/Data/Time/LocalTime.hs
+++ b/Data/Time/LocalTime.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 module Data.Time.LocalTime
 (
diff --git a/Data/Time/LocalTime/LocalTime.hs b/Data/Time/LocalTime/LocalTime.hs
index c902bb6..3d8b7e2 100644
--- a/Data/Time/LocalTime/LocalTime.hs
+++ b/Data/Time/LocalTime/LocalTime.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- #hide
 module Data.Time.LocalTime.LocalTime
diff --git a/Data/Time/LocalTime/TimeOfDay.hs b/Data/Time/LocalTime/TimeOfDay.hs
index ac2de14..c9da692 100644
--- a/Data/Time/LocalTime/TimeOfDay.hs
+++ b/Data/Time/LocalTime/TimeOfDay.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -Wall -Werror #-}
+{-# OPTIONS -Wall #-}
 
 -- #hide
 module Data.Time.LocalTime.TimeOfDay
diff --git a/Data/Time/LocalTime/TimeZone.hs b/Data/Time/LocalTime/TimeZone.hs
index d80671e..577a658 100644
--- a/Data/Time/LocalTime/TimeZone.hs
+++ b/Data/Time/LocalTime/TimeZone.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -ffi -Wall -Werror #-}
+{-# OPTIONS -ffi -Wall #-}
 
 -- #hide
 module Data.Time.LocalTime.TimeZone