compiler: introduce custom "GhcPrelude" Prelude

This switches the compiler/ component to get compiled with
-XNoImplicitPrelude and a `import GhcPrelude` is inserted in all
modules.

This is motivated by the upcoming "Prelude" re-export of
`Semigroup((<>))` which would cause lots of name clashes in every
modulewhich imports also `Outputable`

Reviewers: austin, goldfire, bgamari, alanz, simonmar

Reviewed By: bgamari

Subscribers: goldfire, rwbarton, thomie, mpickering, bgamari

Differential Revision: https://phabricator.haskell.org/D3989

5 files changed, 10 insertions, 0 deletions

diff --git a/compiler/simplStg/RepType.hs b/compiler/simplStg/RepType.hs
index 2acc815125..694aa4ebf7 100644
--- a/compiler/simplStg/RepType.hs
+++ b/compiler/simplStg/RepType.hs
@@ -23,6 +23,8 @@ module RepType
 
 #include "HsVersions.h"
 
+import GhcPrelude
+
 import BasicTypes (Arity, RepArity)
 import DataCon
 import Outputable
diff --git a/compiler/simplStg/SimplStg.hs b/compiler/simplStg/SimplStg.hs
index 6c8b005d80..ad714ea4c8 100644
--- a/compiler/simplStg/SimplStg.hs
+++ b/compiler/simplStg/SimplStg.hs
@@ -10,6 +10,8 @@ module SimplStg ( stg2stg ) where
 
 #include "HsVersions.h"
 
+import GhcPrelude
+
 import StgSyn
 
 import CostCentre       ( CollectedCCs )
diff --git a/compiler/simplStg/StgCse.hs b/compiler/simplStg/StgCse.hs
index b221902768..a35309c181 100644
--- a/compiler/simplStg/StgCse.hs
+++ b/compiler/simplStg/StgCse.hs
@@ -70,6 +70,8 @@ and nothing stops us from transforming that to
 -}
 module StgCse (stgCse) where
 
+import GhcPrelude
+
 import DataCon
 import Id
 import StgSyn
diff --git a/compiler/simplStg/StgStats.hs b/compiler/simplStg/StgStats.hs
index 3f75ae23fa..712ec2d22e 100644
--- a/compiler/simplStg/StgStats.hs
+++ b/compiler/simplStg/StgStats.hs
@@ -27,6 +27,8 @@ module StgStats ( showStgStats ) where
 
 #include "HsVersions.h"
 
+import GhcPrelude
+
 import StgSyn
 
 import Id (Id)
diff --git a/compiler/simplStg/UnariseStg.hs b/compiler/simplStg/UnariseStg.hs
index 2e8fbda02b..6fb8d0ea2d 100644
--- a/compiler/simplStg/UnariseStg.hs
+++ b/compiler/simplStg/UnariseStg.hs
@@ -196,6 +196,8 @@ module UnariseStg (unarise) where
 
 #include "HsVersions.h"
 
+import GhcPrelude
+
 import BasicTypes
 import CoreSyn
 import DataCon