Cleanup BuiltInSyntax vs UserSyntax

There was some confusion about whether FUN/TYPE/One/Many should be
BuiltInSyntax or UserSyntax. The answer is certainly UserSyntax as
BuiltInSyntax is for things which are directly constructed by the parser
rather than going through normal renaming channels.

I fixed all the obviously wrong places I could find and added a test for
the original bug which was caused by this (#21752)

Fixes #21752 #20695 #18302

17 files changed, 45 insertions, 48 deletions

diff --git a/compiler/GHC/Builtin/Names.hs b/compiler/GHC/Builtin/Names.hs
index 6050ceac0d..dba466aa8d 100644
--- a/compiler/GHC/Builtin/Names.hs
+++ b/compiler/GHC/Builtin/Names.hs
@@ -2783,4 +2783,7 @@ pretendNameIsInScope n
     , tYPETyConKey
     , runtimeRepTyConKey, boxedRepDataConKey
     , eqTyConKey
-    , listTyConKey ]
+    , listTyConKey
+    , oneDataConKey
+    , manyDataConKey
+    , funTyConKey ]
diff --git a/compiler/GHC/Builtin/Types.hs b/compiler/GHC/Builtin/Types.hs
index 148b9aa1ca..9410100737 100644
--- a/compiler/GHC/Builtin/Types.hs
+++ b/compiler/GHC/Builtin/Types.hs
@@ -527,14 +527,8 @@ multiplicityTyConName = mkWiredInTyConName UserSyntax gHC_TYPES (fsLit "Multipli
                           multiplicityTyConKey multiplicityTyCon
 
 oneDataConName, manyDataConName :: Name
-oneDataConName = mkWiredInDataConName BuiltInSyntax gHC_TYPES (fsLit "One") oneDataConKey oneDataCon
-manyDataConName = mkWiredInDataConName BuiltInSyntax gHC_TYPES (fsLit "Many") manyDataConKey manyDataCon
- -- It feels wrong to have One and Many be BuiltInSyntax. But otherwise,
- -- `Many`, in particular, is considered out of scope unless an appropriate
- -- file is open. The problem with this is that `Many` appears implicitly in
- -- types every time there is an `(->)`, hence out-of-scope errors get
- -- reported. Making them built-in make it so that they are always considered in
- -- scope.
+oneDataConName = mkWiredInDataConName UserSyntax gHC_TYPES (fsLit "One") oneDataConKey oneDataCon
+manyDataConName = mkWiredInDataConName UserSyntax gHC_TYPES (fsLit "Many") manyDataConKey manyDataCon
 
 runtimeRepTyConName, vecRepDataConName, tupleRepDataConName, sumRepDataConName, boxedRepDataConName :: Name
 runtimeRepTyConName = mkWiredInTyConName UserSyntax gHC_TYPES (fsLit "RuntimeRep") runtimeRepTyConKey runtimeRepTyCon
diff --git a/compiler/GHC/Builtin/Types/Prim.hs b/compiler/GHC/Builtin/Types/Prim.hs
index e4d812a203..2eec67613d 100644
--- a/compiler/GHC/Builtin/Types/Prim.hs
+++ b/compiler/GHC/Builtin/Types/Prim.hs
@@ -11,8 +11,6 @@ Wired-in knowledge about primitive types
 -- | This module defines TyCons that can't be expressed in Haskell.
 --   They are all, therefore, wired-in TyCons.  C.f module "GHC.Builtin.Types"
 module GHC.Builtin.Types.Prim(
-        mkPrimTyConName, -- For implicit parameters in GHC.Builtin.Types only
-
         mkTemplateKindVar, mkTemplateKindVars,
         mkTemplateTyVars, mkTemplateTyVarsFrom,
         mkTemplateKiTyVars, mkTemplateKiTyVar,
@@ -471,7 +469,7 @@ multiplicityTyVar1, multiplicityTyVar2  :: TyVar
 -}
 
 funTyConName :: Name
-funTyConName = mkPrimTyConName (fsLit "FUN") funTyConKey funTyCon
+funTyConName = mkPrimTcName UserSyntax (fsLit "FUN") funTyConKey funTyCon
 
 -- | The @FUN@ type constructor.
 --
@@ -584,12 +582,7 @@ tYPETyCon = mkPrimTyCon tYPETyConName
 
 -- If you edit these, you may need to update the GHC formalism
 -- See Note [GHC Formalism] in GHC.Core.Lint
-tYPETyConName             = mkPrimTyConName (fsLit "TYPE") tYPETyConKey tYPETyCon
-
-mkPrimTyConName :: FastString -> Unique -> TyCon -> Name
-mkPrimTyConName = mkPrimTcName BuiltInSyntax
-  -- All of the super kinds and kinds are defined in Prim,
-  -- and use BuiltInSyntax, because they are never in scope in the source
+tYPETyConName             = mkPrimTcName UserSyntax (fsLit "TYPE") tYPETyConKey tYPETyCon
 
 mkPrimTcName :: BuiltInSyntax -> FastString -> Unique -> TyCon -> Name
 mkPrimTcName built_in_syntax occ key tycon
diff --git a/compiler/GHC/Types/Name/Ppr.hs b/compiler/GHC/Types/Name/Ppr.hs
index 27eb17afed..1d3bf36aba 100644
--- a/compiler/GHC/Types/Name/Ppr.hs
+++ b/compiler/GHC/Types/Name/Ppr.hs
@@ -21,6 +21,7 @@ import GHC.Builtin.Types
 import GHC.Utils.Outputable
 import GHC.Utils.Panic
 import GHC.Utils.Misc
+import GHC.Builtin.Types.Prim (tYPETyConName, funTyConName)
 
 
 {-
@@ -109,7 +110,11 @@ mkPrintUnqualified unit_env env
             , constraintKindTyConName
             , heqTyConName
             , coercibleTyConName
-            , eqTyConName ]
+            , eqTyConName
+            , tYPETyConName
+            , funTyConName
+            , oneDataConName
+            , manyDataConName ]
 
         right_name gre = greDefinitionModule gre == Just mod
 
diff --git a/libraries/base/Data/Typeable/Internal.hs b/libraries/base/Data/Typeable/Internal.hs
index 2d2f735351..69530c911d 100644
--- a/libraries/base/Data/Typeable/Internal.hs
+++ b/libraries/base/Data/Typeable/Internal.hs
@@ -86,10 +86,8 @@ module Data.Typeable.Internal (
     trLiftedRep
   ) where
 
-import GHC.Prim ( FUN )
 import GHC.Base
 import qualified GHC.Arr as A
-import GHC.Types ( TYPE, Multiplicity (Many) )
 import Data.Type.Equality
 import GHC.List ( splitAt, foldl', elem )
 import GHC.Word
diff --git a/libraries/base/GHC/Exception.hs b/libraries/base/GHC/Exception.hs
index 1a3b039416..66982b0043 100644
--- a/libraries/base/GHC/Exception.hs
+++ b/libraries/base/GHC/Exception.hs
@@ -38,7 +38,6 @@ import GHC.Base
 import GHC.Show
 import GHC.Stack.Types
 import GHC.OldList
-import GHC.Prim
 import GHC.IO.Unsafe
 import {-# SOURCE #-} GHC.Stack.CCS
 import GHC.Exception.Type
diff --git a/libraries/base/GHC/Exts.hs b/libraries/base/GHC/Exts.hs
index 662bea8964..f5b2498542 100755
--- a/libraries/base/GHC/Exts.hs
+++ b/libraries/base/GHC/Exts.hs
@@ -25,10 +25,6 @@
 
 module GHC.Exts
        (
-        -- * Primitive types
-
-        FUN, TYPE, -- See https://gitlab.haskell.org/ghc/ghc/issues/18302
-
         -- ** Pointer types
         Ptr(..), FunPtr(..),
 
diff --git a/libraries/base/Unsafe/Coerce.hs b/libraries/base/Unsafe/Coerce.hs
index fd45217fef..76c010a0bf 100644
--- a/libraries/base/Unsafe/Coerce.hs
+++ b/libraries/base/Unsafe/Coerce.hs
@@ -22,8 +22,6 @@ module Unsafe.Coerce
 import GHC.Arr (amap) -- For amap/unsafeCoerce rule
 import GHC.Base
 
-import GHC.Types
-
 {- Note [Implementing unsafeCoerce]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The implementation of unsafeCoerce is surprisingly subtle.
diff --git a/testsuite/tests/module/T21752.hs b/testsuite/tests/module/T21752.hs
new file mode 100644
index 0000000000..72fad0b26a
--- /dev/null
+++ b/testsuite/tests/module/T21752.hs
@@ -0,0 +1,12 @@
+{-# LANGUAGE DataKinds #-}
+module T21752 where
+
+import T21752A
+
+type T = TYPE
+
+type F m a b = FUN m a b
+
+type M = Many
+
+type O = One
diff --git a/testsuite/tests/module/T21752A.hs b/testsuite/tests/module/T21752A.hs
new file mode 100644
index 0000000000..2c4771a112
--- /dev/null
+++ b/testsuite/tests/module/T21752A.hs
@@ -0,0 +1,14 @@
+{-# LANGUAGE PolyKinds #-}
+{-# LANGUAGE DataKinds #-}
+module T21752A (
+    module GHC.Exts
+) where
+
+import GHC.Exts
+
+type T = TYPE
+
+type O = One
+type M = Many
+
+--type F = FUN
diff --git a/testsuite/tests/module/all.T b/testsuite/tests/module/all.T
index 212d9ecbb7..415f40717e 100644
--- a/testsuite/tests/module/all.T
+++ b/testsuite/tests/module/all.T
@@ -293,3 +293,5 @@ test('T13622', normal, compile, [''])
 test('T13704a', normal, compile, ['-main-is Main.program'])
 test('T13704b', [], multimod_compile, ['T13704b1.hs T13704b2.hs', '-main-is T13704b2.program -v0'])
 test('T20562', normal, compile, [''])
+
+test('T21752', [extra_files(['T21752A.hs', 'T21752.hs'])], multimod_compile, ['T21752', '-v0'])
diff --git a/testsuite/tests/rename/should_compile/T18302A.hs b/testsuite/tests/rename/should_compile/T18302A.hs
deleted file mode 100644
index 7df51aa3ea..0000000000
--- a/testsuite/tests/rename/should_compile/T18302A.hs
+++ /dev/null
@@ -1,4 +0,0 @@
-module T18302A ( module GHC.Prim ) where
-
-import GHC.Prim
-
diff --git a/testsuite/tests/rename/should_compile/T18302B.hs b/testsuite/tests/rename/should_compile/T18302B.hs
deleted file mode 100644
index 6c8075fa9f..0000000000
--- a/testsuite/tests/rename/should_compile/T18302B.hs
+++ /dev/null
@@ -1,8 +0,0 @@
--- | Check that TYPE and (->) are re-exportable.
-module T18302B where
-
-import T18302A
-
-type T = TYPE
-type F = (->)
-
diff --git a/testsuite/tests/rename/should_compile/all.T b/testsuite/tests/rename/should_compile/all.T
index ac660606ab..1c02db6e6e 100644
--- a/testsuite/tests/rename/should_compile/all.T
+++ b/testsuite/tests/rename/should_compile/all.T
@@ -176,7 +176,6 @@ test('T17832', [], multimod_compile, ['T17832M1', 'T17832M2'])
 test('T17837', normal, compile, [''])
 test('T18497', [], makefile_test, ['T18497'])
 test('T18264', [], makefile_test, ['T18264'])
-test('T18302', expect_broken(18302), compile, [''])
 test('T17853', [], multimod_compile, ['T17853', '-v0'])
 test('T19966', expect_broken(19966), compile, ['-fdefer-out-of-scope-variables'])
 test('T20472', normal, compile, [''])
diff --git a/testsuite/tests/simplCore/should_compile/T4201.stdout b/testsuite/tests/simplCore/should_compile/T4201.stdout
index baeee0b0af..920ae57662 100644
--- a/testsuite/tests/simplCore/should_compile/T4201.stdout
+++ b/testsuite/tests/simplCore/should_compile/T4201.stdout
@@ -1,4 +1,4 @@
-  lift :: Foo -> T
-  [HasNoCafRefs, TagSig: <TagProper>, LambdaFormInfo: LFReEntrant 1,
    Arity: 1, Strictness: <1!A>, CPR: 1,
-   Unfolding: (bof `cast` (Sym (N:Foo[0]) %<'Many>_N ->_R <T>_R))]
+   Unfolding: (bof
+                 `cast`
+               (Sym (N:Foo[0]) %<'GHC.Types.Many>_N ->_R <T>_R))]
diff --git a/testsuite/tests/typecheck/should_compile/holes.stderr b/testsuite/tests/typecheck/should_compile/holes.stderr
index cde126e969..dd5c497db2 100644
--- a/testsuite/tests/typecheck/should_compile/holes.stderr
+++ b/testsuite/tests/typecheck/should_compile/holes.stderr
@@ -52,8 +52,6 @@ holes.hs:11:15: warning: [-Wtyped-holes (in -Wdefault)]
         LT :: Ordering
         EQ :: Ordering
         GT :: Ordering
-        One :: GHC.Types.Multiplicity
-        Many :: GHC.Types.Multiplicity
         () :: ()
         lines :: String -> [String]
         unlines :: [String] -> String
diff --git a/testsuite/tests/typecheck/should_compile/holes3.stderr b/testsuite/tests/typecheck/should_compile/holes3.stderr
index 4dec2c57a5..c14e9e7b5c 100644
--- a/testsuite/tests/typecheck/should_compile/holes3.stderr
+++ b/testsuite/tests/typecheck/should_compile/holes3.stderr
@@ -55,8 +55,6 @@ holes3.hs:11:15: error:
         LT :: Ordering
         EQ :: Ordering
         GT :: Ordering
-        One :: GHC.Types.Multiplicity
-        Many :: GHC.Types.Multiplicity
         () :: ()
         lines :: String -> [String]
         unlines :: [String] -> String