Add compiler linting to CI

This commit adds the `lint:compiler` Hadrian target to the CI runner.
It does also fixes hints in the compiler/ and libraries/base/ codebases.

4 files changed, 26 insertions, 34 deletions

diff --git a/compiler/GHC/Hs/Binds.hs b/compiler/GHC/Hs/Binds.hs
index 34fc3dc3bb..6383eb01b8 100644
--- a/compiler/GHC/Hs/Binds.hs
+++ b/compiler/GHC/Hs/Binds.hs
@@ -8,7 +8,6 @@
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE UndecidableInstances #-} -- Wrinkle in Note [Trees That Grow]
                                       -- in module Language.Haskell.Syntax.Extension
-{-# LANGUAGE ViewPatterns #-}
 
 {-# OPTIONS_GHC -Wno-orphans #-} -- Outputable
 
diff --git a/compiler/GHC/Hs/Decls.hs b/compiler/GHC/Hs/Decls.hs
index 7592926f07..e5e64267bf 100644
--- a/compiler/GHC/Hs/Decls.hs
+++ b/compiler/GHC/Hs/Decls.hs
@@ -1,17 +1,15 @@
-{-# LANGUAGE CPP                 #-}
-{-# LANGUAGE ConstraintKinds     #-}
-{-# LANGUAGE DeriveDataTypeable  #-}
-{-# LANGUAGE DeriveTraversable   #-}
-{-# LANGUAGE FlexibleContexts    #-}
-{-# LANGUAGE FlexibleInstances   #-}
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE StandaloneDeriving  #-}
-{-# LANGUAGE TypeApplications    #-}
-{-# LANGUAGE TypeFamilies        #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE UndecidableInstances #-} -- Wrinkle in Note [Trees That Grow]
                                       -- in module Language.Haskell.Syntax.Extension
 
-{-# OPTIONS_GHC -Wno-orphans     #-} -- Outputable
+{-# OPTIONS_GHC -Wno-orphans #-} -- Outputable
 
 {-
 (c) The University of Glasgow 2006
diff --git a/compiler/GHC/Hs/Pat.hs b/compiler/GHC/Hs/Pat.hs
index f6ae038745..c5cd2ccb78 100644
--- a/compiler/GHC/Hs/Pat.hs
+++ b/compiler/GHC/Hs/Pat.hs
@@ -1,17 +1,14 @@
-
-{-# LANGUAGE CPP                  #-}
-{-# LANGUAGE ConstraintKinds      #-}
-{-# LANGUAGE DeriveDataTypeable   #-}
-{-# LANGUAGE DeriveTraversable    #-}
-{-# LANGUAGE FlexibleContexts     #-}
-{-# LANGUAGE FlexibleInstances    #-}
-{-# LANGUAGE LambdaCase           #-}
-{-# LANGUAGE ScopedTypeVariables  #-}
-{-# LANGUAGE TypeApplications     #-}
-{-# LANGUAGE TypeFamilies         #-}
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE UndecidableInstances #-} -- Wrinkle in Note [Trees That Grow]
                                       -- in module Language.Haskell.Syntax.Extension
-{-# LANGUAGE ViewPatterns         #-}
 
 {-# OPTIONS_GHC -Wno-orphans #-} -- Outputable
 
diff --git a/compiler/GHC/Hs/Type.hs b/compiler/GHC/Hs/Type.hs
index 4409756958..59fcaf9fe1 100644
--- a/compiler/GHC/Hs/Type.hs
+++ b/compiler/GHC/Hs/Type.hs
@@ -1,15 +1,13 @@
-{-# LANGUAGE CPP                   #-}
-{-# LANGUAGE ConstraintKinds       #-}
-{-# LANGUAGE DeriveDataTypeable    #-}
-{-# LANGUAGE FlexibleContexts      #-}
-{-# LANGUAGE FlexibleInstances     #-}
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
-{-# LANGUAGE ScopedTypeVariables   #-}
-{-# LANGUAGE StandaloneDeriving    #-}
-{-# LANGUAGE TypeApplications      #-}
-{-# LANGUAGE TypeFamilies          #-}
-{-# LANGUAGE ViewPatterns          #-}
-{-# LANGUAGE UndecidableInstances  #-} -- Wrinkle in Note [Trees That Grow]
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE ViewPatterns #-}
+{-# LANGUAGE UndecidableInstances #-} -- Wrinkle in Note [Trees That Grow]
                                        -- in module Language.Haskell.Syntax.Extension
 
 {-# OPTIONS_GHC -Wno-orphans #-} -- NamedThing, Outputable, OutputableBndrId