Fix two wrong uses of "data constructor" in error msgs

Replace `NoDataKinds :: PromotionErr` by `NoDataKindsTC` and
`NoDataKindsDC` (just like there is `NoTypeInTypeTC` and
`NoTypeInTypeDC`). This allows for a correct error message when a kind
signature contains a type constructor and `-XDataKinds` is not
specified.

Apply a small fix to `TcError.hs` where instead of "data constructor" we
should say "pattern synonym".

Reviewers: austin, goldfire, bgamari

Reviewed By: bgamari

Subscribers: goldfire, thomie

Differential Revision: https://phabricator.haskell.org/D1909

3 files changed, 15 insertions, 9 deletions

diff --git a/compiler/typecheck/TcErrors.hs b/compiler/typecheck/TcErrors.hs
index e97e3c566e..1fb2094a57 100644
--- a/compiler/typecheck/TcErrors.hs
+++ b/compiler/typecheck/TcErrors.hs
@@ -39,6 +39,7 @@ import NameSet
 import Bag
 import ErrUtils         ( ErrMsg, errDoc, pprLocErrMsg )
 import BasicTypes
+import ConLike          ( ConLike(..) )
 import Util
 import FastString
 import Outputable
@@ -1839,8 +1840,9 @@ mk_dict_err ctxt (ct, (matches, unifiers, unsafe_overlapped))
                              | orig <- origs ] ] ]
       | otherwise = []
 
-    ppr_skol (PatSkol dc _) = text "the data constructor" <+> quotes (ppr dc)
-    ppr_skol skol_info      = ppr skol_info
+    ppr_skol (PatSkol (RealDataCon dc) _) = text "the data constructor" <+> quotes (ppr dc)
+    ppr_skol (PatSkol (PatSynCon ps)   _) = text "the pattern synonym"  <+> quotes (ppr ps)
+    ppr_skol skol_info = ppr skol_info
 
     extra_note | any isFunTy (filterOutInvisibleTypes (classTyCon clas) tys)
                = text "(maybe you haven't applied a function to enough arguments?)"
diff --git a/compiler/typecheck/TcHsType.hs b/compiler/typecheck/TcHsType.hs
index f5537b60f8..d04ee97285 100644
--- a/compiler/typecheck/TcHsType.hs
+++ b/compiler/typecheck/TcHsType.hs
@@ -987,7 +987,7 @@ tcTyVar mode name         -- Could be a tyvar, a tycon, or a datacon
            ATcTyCon tc_tc -> do { data_kinds <- xoptM LangExt.DataKinds
                                 ; unless (isTypeLevel (mode_level mode) ||
                                           data_kinds) $
-                                  promotionErr name NoDataKinds
+                                  promotionErr name NoDataKindsTC
                                 ; tc <- get_loopy_tc name tc_tc
                                 ; return (mkNakedTyConApp tc [], tyConKind tc_tc) }
                              -- mkNakedTyConApp: see Note [Type-checking inside the knot]
@@ -1001,7 +1001,7 @@ tcTyVar mode name         -- Could be a tyvar, a tycon, or a datacon
                    ; unless (isTypeLevel (mode_level mode) ||
                              data_kinds ||
                              isKindTyCon tc) $
-                       promotionErr name NoDataKinds
+                       promotionErr name NoDataKindsTC
                    ; unless (isTypeLevel (mode_level mode) ||
                              type_in_type ||
                              isLegacyPromotableTyCon tc) $
@@ -1011,7 +1011,7 @@ tcTyVar mode name         -- Could be a tyvar, a tycon, or a datacon
            AGlobal (AConLike (RealDataCon dc))
              -> do { data_kinds <- xoptM LangExt.DataKinds
                    ; unless (data_kinds || specialPromotedDc dc) $
-                       promotionErr name NoDataKinds
+                       promotionErr name NoDataKindsDC
                    ; type_in_type <- xoptM LangExt.TypeInType
                    ; unless ( type_in_type ||
                               ( isTypeLevel (mode_level mode) &&
@@ -2142,7 +2142,8 @@ promotionErr name err
   where
     reason = case err of
                FamDataConPE   -> text "it comes from a data family instance"
-               NoDataKinds    -> text "Perhaps you intended to use DataKinds"
+               NoDataKindsTC  -> text "Perhaps you intended to use DataKinds"
+               NoDataKindsDC  -> text "Perhaps you intended to use DataKinds"
                NoTypeInTypeTC -> text "Perhaps you intended to use TypeInType"
                NoTypeInTypeDC -> text "Perhaps you intended to use TypeInType"
                PatSynPE       -> text "Pattern synonyms cannot be promoted"
diff --git a/compiler/typecheck/TcRnTypes.hs b/compiler/typecheck/TcRnTypes.hs
index 7d7f265b78..0810ac8070 100644
--- a/compiler/typecheck/TcRnTypes.hs
+++ b/compiler/typecheck/TcRnTypes.hs
@@ -905,7 +905,8 @@ data PromotionErr
 
   | RecDataConPE     -- Data constructor in a recursive loop
                      -- See Note [ARecDataCon: recusion and promoting data constructors] in TcTyClsDecls
-  | NoDataKinds      -- -XDataKinds not enabled
+  | NoDataKindsTC    -- -XDataKinds not enabled (for a tycon)
+  | NoDataKindsDC    -- -XDataKinds not enabled (for a datacon)
   | NoTypeInTypeTC   -- -XTypeInType not enabled (for a tycon)
   | NoTypeInTypeDC   -- -XTypeInType not enabled (for a datacon)
 
@@ -925,7 +926,8 @@ instance Outputable PromotionErr where
   ppr PatSynPE       = text "PatSynPE"
   ppr FamDataConPE   = text "FamDataConPE"
   ppr RecDataConPE   = text "RecDataConPE"
-  ppr NoDataKinds    = text "NoDataKinds"
+  ppr NoDataKindsTC  = text "NoDataKindsTC"
+  ppr NoDataKindsDC  = text "NoDataKindsDC"
   ppr NoTypeInTypeTC = text "NoTypeInTypeTC"
   ppr NoTypeInTypeDC = text "NoTypeInTypeDC"
 
@@ -942,7 +944,8 @@ pprPECategory TyConPE        = text "Type constructor"
 pprPECategory PatSynPE       = text "Pattern synonym"
 pprPECategory FamDataConPE   = text "Data constructor"
 pprPECategory RecDataConPE   = text "Data constructor"
-pprPECategory NoDataKinds    = text "Data constructor"
+pprPECategory NoDataKindsTC  = text "Type constructor"
+pprPECategory NoDataKindsDC  = text "Data constructor"
 pprPECategory NoTypeInTypeTC = text "Type constructor"
 pprPECategory NoTypeInTypeDC = text "Data constructor"