7 files changed, 4 insertions, 59 deletions
diff --git a/compiler/utils/IOEnv.hs b/compiler/utils/IOEnv.hs
index 29854c51fe..5a7ccd9972 100644
--- a/compiler/utils/IOEnv.hs
+++ b/compiler/utils/IOEnv.hs
@@ -1,5 +1,3 @@
-{-# LANGUAGE CPP #-}
-
 --
 -- (c) The University of Glasgow 2002-2006
 --
@@ -41,9 +39,7 @@ import Data.IORef       ( IORef, newIORef, readIORef, writeIORef, modifyIORef,
 import System.IO.Unsafe ( unsafeInterleaveIO )
 import System.IO        ( fixIO )
 import Control.Monad
-#if __GLASGOW_HASKELL__ > 710
 import qualified Control.Monad.Fail as MonadFail
-#endif
 import MonadUtils
 import Control.Applicative (Alternative(..))
 
@@ -62,11 +58,8 @@ instance Monad (IOEnv m) where
     (>>)   = (*>)
     fail _ = failM -- Ignore the string
 
-#if __GLASGOW_HASKELL__ > 710
 instance MonadFail.MonadFail (IOEnv m) where
     fail _ = failM -- Ignore the string
-#endif
-
 
 instance Applicative (IOEnv m) where
     pure = returnM
diff --git a/compiler/utils/MonadUtils.hs b/compiler/utils/MonadUtils.hs
index 93a835e04e..d6fb31731e 100644
--- a/compiler/utils/MonadUtils.hs
+++ b/compiler/utils/MonadUtils.hs
@@ -1,5 +1,3 @@
-{-# LANGUAGE CPP #-}
-
 -- | Utilities related to Monad and Applicative classes
 --   Mostly for backwards compatibility.
 
@@ -34,9 +32,6 @@ import Maybes
 import Control.Monad
 import Control.Monad.Fix
 import Control.Monad.IO.Class
-#if __GLASGOW_HASKELL__ < 800
-import Control.Monad.Trans.Error () -- for orphan `instance MonadPlus IO`
-#endif
 
 -------------------------------------------------------------------------------
 -- Lift combinators
diff --git a/compiler/utils/OrdList.hs b/compiler/utils/OrdList.hs
index 3c5b9d7380..1660090ba7 100644
--- a/compiler/utils/OrdList.hs
+++ b/compiler/utils/OrdList.hs
@@ -9,7 +9,6 @@ Provide trees (of instructions), so that lists of instructions
 can be appended in linear time.
 -}
 
-{-# LANGUAGE CPP #-}
 module OrdList (
         OrdList,
         nilOL, isNilOL, unitOL, appOL, consOL, snocOL, concatOL, lastOL,
@@ -18,10 +17,8 @@ module OrdList (
 
 import Outputable
 
-#if __GLASGOW_HASKELL__ > 710
 import Data.Semigroup   ( Semigroup )
 import qualified Data.Semigroup as Semigroup
-#endif
 
 infixl 5  `appOL`
 infixl 5  `snocOL`
@@ -39,10 +36,8 @@ data OrdList a
 instance Outputable a => Outputable (OrdList a) where
   ppr ol = ppr (fromOL ol)  -- Convert to list and print that
 
-#if __GLASGOW_HASKELL__ > 710
 instance Semigroup (OrdList a) where
   (<>) = appOL
-#endif
 
 instance Monoid (OrdList a) where
   mempty = nilOL
diff --git a/compiler/utils/Outputable.hs b/compiler/utils/Outputable.hs
index 4107e5beef..de27546ac4 100644
--- a/compiler/utils/Outputable.hs
+++ b/compiler/utils/Outputable.hs
@@ -122,6 +122,7 @@ import Data.List (intersperse)
 
 import GHC.Fingerprint
 import GHC.Show         ( showMultiLineString )
+import GHC.Stack        ( callStack, prettyCallStack )
 
 {-
 ************************************************************************
@@ -1130,7 +1131,8 @@ doOrDoes _   = text "do"
 
 callStackDoc :: HasCallStack => SDoc
 callStackDoc =
-    hang (text "Call stack:") 4 (vcat $ map text $ lines prettyCurrentCallStack)
+    hang (text "Call stack:")
+       4 (vcat $ map text $ lines (prettyCallStack callStack))
 
 pprPanic :: HasCallStack => String -> SDoc -> a
 -- ^ Throw an exception saying "bug in GHC"
diff --git a/compiler/utils/UniqFM.hs b/compiler/utils/UniqFM.hs
index 71a092b28e..8ea8ba4537 100644
--- a/compiler/utils/UniqFM.hs
+++ b/compiler/utils/UniqFM.hs
@@ -85,10 +85,8 @@ import qualified Data.Monoid as Mon
 import qualified Data.IntSet as S
 import Data.Typeable
 import Data.Data
-#if __GLASGOW_HASKELL__ > 710
 import Data.Semigroup   ( Semigroup )
 import qualified Data.Semigroup as Semigroup
-#endif
 
 
 newtype UniqFM ele = UFM (M.IntMap ele)
@@ -358,10 +356,8 @@ equalKeysUFM (UFM m1) (UFM m2) = M.keys m1 == M.keys m2
 
 -- Instances
 
-#if __GLASGOW_HASKELL__ > 710
 instance Semigroup (UniqFM a) where
   (<>) = plusUFM
-#endif
 
 instance Monoid (UniqFM a) where
     mempty = emptyUFM
diff --git a/compiler/utils/UniqSet.hs b/compiler/utils/UniqSet.hs
index f29a1e6e1f..fcac865ea8 100644
--- a/compiler/utils/UniqSet.hs
+++ b/compiler/utils/UniqSet.hs
@@ -9,7 +9,6 @@ Based on @UniqFMs@ (as you would expect).
 Basically, the things need to be in class @Uniquable@.
 -}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE DeriveDataTypeable #-}
 
 module UniqSet (
@@ -53,9 +52,7 @@ import Data.Coerce
 import Outputable
 import Data.Foldable (foldl')
 import Data.Data
-#if __GLASGOW_HASKELL__ >= 801
 import qualified Data.Semigroup
-#endif
 
 -- Note [UniqSet invariant]
 -- ~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -189,10 +186,8 @@ unsafeUFMToUniqSet = UniqSet
 
 instance Outputable a => Outputable (UniqSet a) where
     ppr = pprUniqSet ppr
-#if __GLASGOW_HASKELL__ >= 801
 instance Data.Semigroup.Semigroup (UniqSet a) where
   (<>) = mappend
-#endif
 instance Monoid (UniqSet a) where
   mempty = UniqSet mempty
   UniqSet s `mappend` UniqSet t = UniqSet (s `mappend` t)
diff --git a/compiler/utils/Util.hs b/compiler/utils/Util.hs
index 35a6340fd4..6146bf0113 100644
--- a/compiler/utils/Util.hs
+++ b/compiler/utils/Util.hs
@@ -4,11 +4,6 @@
 {-# LANGUAGE KindSignatures #-}
 {-# LANGUAGE ConstraintKinds #-}
 {-# LANGUAGE BangPatterns #-}
-#if __GLASGOW_HASKELL__ < 800
--- For CallStack business
-{-# LANGUAGE ImplicitParams #-}
-{-# LANGUAGE FlexibleContexts #-}
-#endif
 
 -- | Highly random utility functions
 --
@@ -124,12 +119,8 @@ module Util (
         hashString,
 
         -- * Call stacks
-#if MIN_VERSION_GLASGOW_HASKELL(7,10,2,0)
-        GHC.Stack.CallStack,
-#endif
         HasCallStack,
         HasDebugCallStack,
-        prettyCurrentCallStack,
 
         -- * Utils for flags
         OverridingBool(..),
@@ -147,7 +138,7 @@ import System.IO.Unsafe ( unsafePerformIO )
 import Data.List        hiding (group)
 
 import GHC.Exts
-import qualified GHC.Stack
+import GHC.Stack (HasCallStack)
 
 import Control.Applicative ( liftA2 )
 import Control.Monad    ( liftM )
@@ -1368,16 +1359,6 @@ mulHi a b = fromIntegral (r `shiftR` 32)
    where r :: Int64
          r = fromIntegral a * fromIntegral b
 
--- | A compatibility wrapper for the @GHC.Stack.HasCallStack@ constraint.
-#if __GLASGOW_HASKELL__ >= 800
-type HasCallStack = GHC.Stack.HasCallStack
-#elif MIN_VERSION_GLASGOW_HASKELL(7,10,2,0)
-type HasCallStack = (?callStack :: GHC.Stack.CallStack)
--- CallStack wasn't present in GHC 7.10.1, disable callstacks in stage 1
-#else
-type HasCallStack = (() :: Constraint)
-#endif
-
 -- | A call stack constraint, but only when 'isDebugOn'.
 #if defined(DEBUG)
 type HasDebugCallStack = HasCallStack
@@ -1385,18 +1366,6 @@ type HasDebugCallStack = HasCallStack
 type HasDebugCallStack = (() :: Constraint)
 #endif
 
--- | Pretty-print the current callstack
-#if __GLASGOW_HASKELL__ >= 800
-prettyCurrentCallStack :: HasCallStack => String
-prettyCurrentCallStack = GHC.Stack.prettyCallStack GHC.Stack.callStack
-#elif MIN_VERSION_GLASGOW_HASKELL(7,10,2,0)
-prettyCurrentCallStack :: (?callStack :: GHC.Stack.CallStack) => String
-prettyCurrentCallStack = GHC.Stack.showCallStack ?callStack
-#else
-prettyCurrentCallStack :: HasCallStack => String
-prettyCurrentCallStack = "Call stack unavailable"
-#endif
-
 data OverridingBool
   = Auto
   | Always