Print foralls in user format

This fixes Trac #12597: in RnNames.warnMissingSignatures,
use pprSigmaType not pprType

compiler/rename/RnNames.hs

@@ -1615,7 +1615,7 @@ warnMissingSignatures gbl_env
                     = do { env <- tcInitTidyEnv     -- Why not use emptyTidyEnv?
                          ; let name    = idName id
                                (_, ty) = tidyOpenType env (idType id)
-                               ty_msg  = ppr ty
+                               ty_msg  = pprSigmaType ty
                          ; add_warn name $
                            hang (text "Top-level binding with no type signature:")
                               2 (pprPrefixName name <+> dcolon <+> ty_msg) }

compiler/types/TyCoRep.hs

@@ -2689,6 +2689,8 @@ ppr_fun_tail (FunTy ty1 ty2)
 ppr_fun_tail other_ty = [ppr_type TopPrec other_ty]
 
 pprSigmaType :: Type -> SDoc
+-- Prints a top-level type for the user; in particular
+-- top-level foralls are omitted unless you use -fprint-explicit-foralls
 pprSigmaType ty = sdocWithDynFlags $ \dflags ->
                   eliminateRuntimeRep (ppr_sigma_type dflags False) ty
 

testsuite/tests/driver/werror.stderr

@@ -17,8 +17,7 @@ werror.hs:10:1: warning: [-Wunused-top-binds (in -Wextra, -Wunused-binds)]
     Defined but not used: ‘f’
 
 werror.hs:10:1: warning: [-Wmissing-signatures (in -Wall)]
-    Top-level binding with no type signature:
-      f :: forall a1 a2. [a2] -> [a1]
+    Top-level binding with no type signature: f :: [a2] -> [a1]
 
 werror.hs:10:1: warning: [-Wincomplete-patterns (in -Wextra)]
     Pattern match(es) are non-exhaustive

testsuite/tests/indexed-types/should_compile/T8889.stderr

 
 T8889.hs:12:1: warning: [-Wmissing-signatures (in -Wall)]
     Top-level binding with no type signature:
-      f :: forall (f :: * -> *) b a.
-           (C f, C_fmap f a) =>
-           (a -> b) -> f a -> f b
+      f :: (C f, C_fmap f a) => (a -> b) -> f a -> f b

testsuite/tests/parser/should_compile/read014.stderr

 
 read014.hs:4:1: warning: [-Wmissing-signatures (in -Wall)]
     Top-level binding with no type signature:
-      ng1 :: forall a t. Num a => t -> a -> a
+      ng1 :: Num a => t -> a -> a
 
 read014.hs:4:5: warning: [-Wunused-matches (in -Wextra)]
     Defined but not used: ‘x’

testsuite/tests/rename/should_compile/T12597.hs

+{-# OPTIONS_GHC -Wmissing-signatures #-}
+
+module T12597 where
+
+f x = x

testsuite/tests/rename/should_compile/T12597.stderr

+
+T12597.hs:5:1: warning: [-Wmissing-signatures (in -Wall)]
+    Top-level binding with no type signature: f :: t -> t

testsuite/tests/rename/should_compile/all.T

@@ -243,3 +243,4 @@ test('T12127',
      multimod_compile,
      ['T12127', '-v0'])
 test('T12533', normal, compile, [''])
+test('T12597', normal, compile, [''])

testsuite/tests/typecheck/should_compile/T10971a.stderr

 
 T10971a.hs:7:1: warning: [-Wmissing-signatures (in -Wall)]
-    Top-level binding with no type signature: f :: forall a. [a] -> Int
+    Top-level binding with no type signature: f :: [a] -> Int
 
 T10971a.hs:7:11: warning: [-Wtype-defaults (in -Wall)]
     • Defaulting the following constraint to type ‘[]’
@@ -11,7 +11,7 @@ T10971a.hs:7:11: warning: [-Wtype-defaults (in -Wall)]
 
 T10971a.hs:8:1: warning: [-Wmissing-signatures (in -Wall)]
     Top-level binding with no type signature:
-      g :: forall b a. (a -> b) -> [a] -> [b]
+      g :: (a -> b) -> [a] -> [b]
 
 T10971a.hs:8:6: warning: [-Wname-shadowing (in -Wall)]
     This binding for ‘f’ shadows the existing binding
@@ -26,7 +26,7 @@ T10971a.hs:8:13: warning: [-Wtype-defaults (in -Wall)]
 
 T10971a.hs:9:1: warning: [-Wmissing-signatures (in -Wall)]
     Top-level binding with no type signature:
-      h :: forall b a. (a -> b) -> [a] -> ([b], Int)
+      h :: (a -> b) -> [a] -> ([b], Int)
 
 T10971a.hs:9:6: warning: [-Wname-shadowing (in -Wall)]
     This binding for ‘f’ shadows the existing binding

testsuite/tests/typecheck/should_compile/tc243.stderr

 
 tc243.hs:10:1: warning: [-Wmissing-signatures (in -Wall)]
-    Top-level binding with no type signature: (.+.) :: forall a. a
+    Top-level binding with no type signature: (.+.) :: a

testsuite/tests/warnings/should_compile/T11077.stderr

 
 T11077.hs:3:1: warning: [-Wmissing-exported-sigs]
-    Top-level binding with no type signature: foo :: forall a. a
+    Top-level binding with no type signature: foo :: a