diff --git a/Cabal/src/Distribution/Simple.hs b/Cabal/src/Distribution/Simple.hs
index 114c60a1add..4d7429f74a6 100644
--- a/Cabal/src/Distribution/Simple.hs
+++ b/Cabal/src/Distribution/Simple.hs
@@ -14,7 +14,6 @@ libraries/Cabal/Distribution/Simple.hs:78:0:
              Deprecated: "Please use the new testing interface instead!"
 -}
 {-# OPTIONS_GHC -Wno-deprecations #-}
-{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
 
 -- |
 -- Module      :  Distribution.Simple
diff --git a/cabal-install/src/Distribution/Client/BuildReports/Storage.hs b/cabal-install/src/Distribution/Client/BuildReports/Storage.hs
index 740a32cd9c3..7bb56affa42 100644
--- a/cabal-install/src/Distribution/Client/BuildReports/Storage.hs
+++ b/cabal-install/src/Distribution/Client/BuildReports/Storage.hs
@@ -1,5 +1,3 @@
-{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
-
 -----------------------------------------------------------------------------
 
 -----------------------------------------------------------------------------
@@ -91,13 +89,15 @@ storeAnonymous reports =
     separate
       :: [(BuildReport, Maybe Repo)]
       -> [(Repo, [BuildReport])]
-    separate =
-      map (\rs@((_, repo, _) : _) -> (repo, [r | (r, _, _) <- rs]))
-        . map (concatMap toList)
-        . L.groupBy (equating (repoName' . head))
-        . sortBy (comparing (repoName' . head))
-        . groupBy (equating repoName')
-        . onlyRemote
+    separate xs =
+      [ (repo, [r | (r, _, _) <- rs])
+      | rs@((_, repo, _) : _) <-
+          map (concatMap toList)
+            . L.groupBy (equating (repoName' . head))
+            . sortBy (comparing (repoName' . head))
+            . groupBy (equating repoName')
+            $ onlyRemote xs
+      ]
 
     repoName' (_, _, rrepo) = remoteRepoName rrepo
 
@@ -148,10 +148,10 @@ storeLocal cinfo templates reports platform =
             cinfo
             platform
 
-    groupByFileName =
-      map (\grp@((filename, _) : _) -> (filename, map snd grp))
-        . L.groupBy (equating fst)
-        . sortBy (comparing fst)
+    groupByFileName xs =
+      [ (filename, map snd grp)
+      | grp@((filename, _) : _) <- L.groupBy (equating fst) $ sortBy (comparing fst) xs
+      ]
 
 -- ------------------------------------------------------------
 
diff --git a/cabal-install/src/Distribution/Client/Errors.hs b/cabal-install/src/Distribution/Client/Errors.hs
index d35ec41ddca..8f02620c6d8 100644
--- a/cabal-install/src/Distribution/Client/Errors.hs
+++ b/cabal-install/src/Distribution/Client/Errors.hs
@@ -1,7 +1,6 @@
 {-# LANGUAGE ConstraintKinds #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE InstanceSigs #-}
-{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
 
 -----------------------------------------------------------------------------
 
@@ -712,22 +711,19 @@ exceptionMessageCabalInstall e = case e of
                   | (thing, _got, alts@(_ : _)) <- nosuch'
                   ]
           ]
-      | let groupByContainer =
-              map
-                ( \g@((inside, _, _, _) : _) ->
-                    ( inside
-                    , [ (thing, got, alts)
-                      | (_, thing, got, alts) <- g
-                      ]
-                    )
-                )
-                . groupBy ((==) `on` (\(x, _, _, _) -> x))
-                . sortBy (compare `on` (\(x, _, _, _) -> x))
-      , (target, nosuch) <- targets
+      | (target, nosuch) <- targets
       ]
     where
       mungeThing "file" = "file target"
       mungeThing thing = thing
+      groupByContainer xs =
+        [ ( inside
+          , [ (thing, got, alts)
+            | (_, thing, got, alts) <- g
+            ]
+          )
+        | g@((inside, _, _, _) : _) <- groupBy ((==) `on` (\(x, _, _, _) -> x)) $ sortBy (compare `on` (\(x, _, _, _) -> x)) xs
+        ]
   TargetSelectorAmbiguousErr targets ->
     unlines
       [ "Ambiguous target '"
diff --git a/cabal-install/src/Distribution/Client/TargetSelector.hs b/cabal-install/src/Distribution/Client/TargetSelector.hs
index 56ea25d958e..85438ac5387 100644
--- a/cabal-install/src/Distribution/Client/TargetSelector.hs
+++ b/cabal-install/src/Distribution/Client/TargetSelector.hs
@@ -1,10 +1,10 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE NamedFieldPuns #-}
 {-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE ScopedTypeVariables #-}
--- TODO
-{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
+{-# LANGUAGE ViewPatterns #-}
 
 -----------------------------------------------------------------------------
 
@@ -765,9 +765,7 @@ disambiguateTargetSelectors matcher matchInput exactMatch matchResults =
           Left
             ( originalMatch
             , [ (forgetFileStatus rendering, matches)
-              | rendering <- matchRenderings
-              , let Match m _ matches =
-                      memoisedMatches Map.! rendering
+              | rendering@((memoisedMatches Map.!?) -> Just (Match m _ matches)) <- matchRenderings
               , m /= Inexact
               ]
             )
@@ -1107,7 +1105,7 @@ syntaxForm1File ps =
   -- all the other forms we don't require that.
   syntaxForm1 render $ \str1 fstatus1 ->
     expecting "file" str1 $ do
-      (pkgfile, ~KnownPackage{pinfoId, pinfoComponents}) <-
+      (pkgfile, KnownPackage{pinfoId, pinfoComponents}) <-
         -- always returns the KnownPackage case
         matchPackageDirectoryPrefix ps fstatus1
       orNoThingIn "package" (prettyShow (packageName pinfoId)) $ do
@@ -1722,44 +1720,41 @@ syntaxForm3 :: Renderer -> Match3 -> Syntax
 syntaxForm4 :: Renderer -> Match4 -> Syntax
 syntaxForm5 :: Renderer -> Match5 -> Syntax
 syntaxForm7 :: Renderer -> Match7 -> Syntax
-syntaxForm1 render f =
-  Syntax QL1 match render
+syntaxForm1 render f = Syntax QL1 match render
   where
-    match = \(TargetStringFileStatus1 str1 fstatus1) ->
-      f str1 fstatus1
+    match = \case
+      TargetStringFileStatus1 str1 fstatus1 -> f str1 fstatus1
+      _ -> mzero
 
-syntaxForm2 render f =
-  Syntax QL2 match render
+syntaxForm2 render f = Syntax QL2 match render
   where
-    match = \(TargetStringFileStatus2 str1 fstatus1 str2) ->
-      f str1 fstatus1 str2
+    match = \case
+      TargetStringFileStatus2 str1 fstatus1 str2 -> f str1 fstatus1 str2
+      _ -> mzero
 
-syntaxForm3 render f =
-  Syntax QL3 match render
+syntaxForm3 render f = Syntax QL3 match render
   where
-    match = \(TargetStringFileStatus3 str1 fstatus1 str2 str3) ->
-      f str1 fstatus1 str2 str3
+    match = \case
+      TargetStringFileStatus3 str1 fstatus1 str2 str3 -> f str1 fstatus1 str2 str3
+      _ -> mzero
 
-syntaxForm4 render f =
-  Syntax QLFull match render
+syntaxForm4 render f = Syntax QLFull match render
   where
-    match (TargetStringFileStatus4 str1 str2 str3 str4) =
-      f str1 str2 str3 str4
-    match _ = mzero
+    match = \case
+      TargetStringFileStatus4 str1 str2 str3 str4 -> f str1 str2 str3 str4
+      _ -> mzero
 
-syntaxForm5 render f =
-  Syntax QLFull match render
+syntaxForm5 render f = Syntax QLFull match render
   where
-    match (TargetStringFileStatus5 str1 str2 str3 str4 str5) =
-      f str1 str2 str3 str4 str5
-    match _ = mzero
+    match = \case
+      TargetStringFileStatus5 str1 str2 str3 str4 str5 -> f str1 str2 str3 str4 str5
+      _ -> mzero
 
-syntaxForm7 render f =
-  Syntax QLFull match render
+syntaxForm7 render f = Syntax QLFull match render
   where
-    match (TargetStringFileStatus7 str1 str2 str3 str4 str5 str6 str7) =
-      f str1 str2 str3 str4 str5 str6 str7
-    match _ = mzero
+    match = \case
+      TargetStringFileStatus7 str1 str2 str3 str4 str5 str6 str7 -> f str1 str2 str3 str4 str5 str6 str7
+      _ -> mzero
 
 dispP :: Package p => p -> String
 dispP = prettyShow . packageName
@@ -2391,6 +2386,9 @@ instance MonadPlus Match where
   mzero = empty
   mplus = matchPlus
 
+instance MonadFail Match where
+  fail _ = mzero
+
 (</>) :: Match a -> Match a -> Match a
 (</>) = matchPlusShadowing