Add the proper HLint rules and remove redundant keywords from compiler

5 files changed, 41 insertions, 48 deletions

diff --git a/compiler/GHC/Utils/Binary.hs b/compiler/GHC/Utils/Binary.hs
index dbc2cdc195..1579eeb5a8 100644
--- a/compiler/GHC/Utils/Binary.hs
+++ b/compiler/GHC/Utils/Binary.hs
@@ -3,7 +3,6 @@
 {-# LANGUAGE PolyKinds #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE GADTs #-}
-{-# LANGUAGE MultiWayIf #-}
 {-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE StandaloneDeriving #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
diff --git a/compiler/GHC/Utils/Error.hs b/compiler/GHC/Utils/Error.hs
index 2db4672f07..25da8be3de 100644
--- a/compiler/GHC/Utils/Error.hs
+++ b/compiler/GHC/Utils/Error.hs
@@ -1,6 +1,5 @@
 {-# LANGUAGE BangPatterns    #-}
 {-# LANGUAGE CPP             #-}
-{-# LANGUAGE LambdaCase      #-}
 {-# LANGUAGE RankNTypes      #-}
 
 {-
@@ -124,10 +123,6 @@ orValid IsValid _ = IsValid
 orValid _       v = v
 
 -- -----------------------------------------------------------------------------
--- Basic error messages: just render a message with a source location.
-
-
--- -----------------------------------------------------------------------------
 -- Collecting up messages for later ordering and printing.
 
 mk_err_msg :: DynFlags -> Severity -> SrcSpan -> PrintUnqualified -> ErrDoc -> ErrMsg
@@ -536,42 +531,42 @@ withTiming' :: MonadIO m
             -> m a          -- ^ The body of the phase to be timed
             -> m a
 withTiming' dflags what force_result prtimings action
-  = do if verbosity dflags >= 2 || dopt Opt_D_dump_timings dflags
-          then do whenPrintTimings $
-                    logInfo dflags $ withPprStyle defaultUserStyle $
-                      text "***" <+> what <> colon
-                  let ctx = initDefaultSDocContext dflags
-                  eventBegins ctx what
-                  alloc0 <- liftIO getAllocationCounter
-                  start <- liftIO getCPUTime
-                  !r <- action
-                  () <- pure $ force_result r
-                  eventEnds ctx what
-                  end <- liftIO getCPUTime
-                  alloc1 <- liftIO getAllocationCounter
-                  -- recall that allocation counter counts down
-                  let alloc = alloc0 - alloc1
-                      time = realToFrac (end - start) * 1e-9
-
-                  when (verbosity dflags >= 2 && prtimings == PrintTimings)
-                      $ liftIO $ logInfo dflags $ withPprStyle defaultUserStyle
-                          (text "!!!" <+> what <> colon <+> text "finished in"
-                           <+> doublePrec 2 time
-                           <+> text "milliseconds"
-                           <> comma
-                           <+> text "allocated"
-                           <+> doublePrec 3 (realToFrac alloc / 1024 / 1024)
-                           <+> text "megabytes")
-
-                  whenPrintTimings $
-                      dumpIfSet_dyn dflags Opt_D_dump_timings "" FormatText
-                          $ text $ showSDocOneLine ctx
-                          $ hsep [ what <> colon
-                                 , text "alloc=" <> ppr alloc
-                                 , text "time=" <> doublePrec 3 time
-                                 ]
-                  pure r
-           else action
+  = if verbosity dflags >= 2 || dopt Opt_D_dump_timings dflags
+    then do whenPrintTimings $
+              logInfo dflags $ withPprStyle defaultUserStyle $
+                text "***" <+> what <> colon
+            let ctx = initDefaultSDocContext dflags
+            eventBegins ctx what
+            alloc0 <- liftIO getAllocationCounter
+            start <- liftIO getCPUTime
+            !r <- action
+            () <- pure $ force_result r
+            eventEnds ctx what
+            end <- liftIO getCPUTime
+            alloc1 <- liftIO getAllocationCounter
+            -- recall that allocation counter counts down
+            let alloc = alloc0 - alloc1
+                time = realToFrac (end - start) * 1e-9
+
+            when (verbosity dflags >= 2 && prtimings == PrintTimings)
+                $ liftIO $ logInfo dflags $ withPprStyle defaultUserStyle
+                    (text "!!!" <+> what <> colon <+> text "finished in"
+                     <+> doublePrec 2 time
+                     <+> text "milliseconds"
+                     <> comma
+                     <+> text "allocated"
+                     <+> doublePrec 3 (realToFrac alloc / 1024 / 1024)
+                     <+> text "megabytes")
+
+            whenPrintTimings $
+                dumpIfSet_dyn dflags Opt_D_dump_timings "" FormatText
+                    $ text $ showSDocOneLine ctx
+                    $ hsep [ what <> colon
+                           , text "alloc=" <> ppr alloc
+                           , text "time=" <> doublePrec 3 time
+                           ]
+            pure r
+     else action
 
     where whenPrintTimings = liftIO . when (prtimings == PrintTimings)
           eventBegins ctx w = do
@@ -776,8 +771,8 @@ type TraceAction = forall a. DynFlags -> String -> SDoc -> a -> a
 
 -- | Default action for 'dumpAction' hook
 defaultDumpAction :: DumpAction
-defaultDumpAction dflags sty dumpOpt title _fmt doc = do
-   dumpSDocWithStyle sty dflags dumpOpt title doc
+defaultDumpAction dflags sty dumpOpt title _fmt doc =
+  dumpSDocWithStyle sty dflags dumpOpt title doc
 
 -- | Default action for 'traceAction' hook
 defaultTraceAction :: TraceAction
diff --git a/compiler/GHC/Utils/Exception.hs b/compiler/GHC/Utils/Exception.hs
index 49fa19bd47..46c1f9d37d 100644
--- a/compiler/GHC/Utils/Exception.hs
+++ b/compiler/GHC/Utils/Exception.hs
@@ -3,14 +3,13 @@
 
 module GHC.Utils.Exception
     (
-    module Control.Exception,
+    module CE,
     module GHC.Utils.Exception
     )
     where
 
 import GHC.Prelude
 
-import Control.Exception
 import Control.Exception as CE
 import Control.Monad.IO.Class
 import Control.Monad.Catch
diff --git a/compiler/GHC/Utils/GlobalVars.hs b/compiler/GHC/Utils/GlobalVars.hs
index 5556a7e4f1..f169d07161 100644
--- a/compiler/GHC/Utils/GlobalVars.hs
+++ b/compiler/GHC/Utils/GlobalVars.hs
@@ -95,7 +95,7 @@ global :: a -> IORef a
 global a = unsafePerformIO (newIORef a)
 
 consIORef :: IORef [a] -> a -> IO ()
-consIORef var x = do
+consIORef var x =
   atomicModifyIORef' var (\xs -> (x:xs,()))
 
 globalM :: IO a -> IORef a
diff --git a/compiler/GHC/Utils/Misc.hs b/compiler/GHC/Utils/Misc.hs
index 7436487739..07d4b721ff 100644
--- a/compiler/GHC/Utils/Misc.hs
+++ b/compiler/GHC/Utils/Misc.hs
@@ -1281,7 +1281,7 @@ getModificationUTCTime = getModificationTime
 -- check existence & modification time at the same time
 
 modificationTimeIfExists :: FilePath -> IO (Maybe UTCTime)
-modificationTimeIfExists f = do
+modificationTimeIfExists f =
   (do t <- getModificationUTCTime f; return (Just t))
         `catchIO` \e -> if isDoesNotExistError e
                         then return Nothing