Remove GHC's haskell98 dependency

[ghc-hetmet.git] / compiler / typecheck / TcTyClsDecls.lhs

diff --git a/compiler/typecheck/TcTyClsDecls.lhs b/compiler/typecheck/TcTyClsDecls.lhs
index 633dc52..bc20d3d 100644 (file)
--- a/compiler/typecheck/TcTyClsDecls.lhs
+++ b/compiler/typecheck/TcTyClsDecls.lhs
@@ -13,7 +13,6 @@ module TcTyClsDecls (
 #include "HsVersions.h"
 
 import HsSyn
-import HsTypes
 import HscTypes
 import BuildTyCl
 import TcUnify
@@ -36,10 +35,8 @@ import IdInfo
 import Var
 import VarSet
 import Name
-import OccName
 import Outputable
 import Maybes
-import Monad
 import Unify
 import Util
 import SrcLoc
@@ -51,8 +48,8 @@ import Unique         ( mkBuiltinUnique )
 import BasicTypes
 
 import Bag
+import Control.Monad
 import Data.List
-import Control.Monad    ( mplus )
 \end{code}
 
 
@@ -293,7 +290,7 @@ tcFamInstDecl1 (decl@TySynonym {tcdLName = L loc tc_name})
        ; checkValidTypeInst t_typats t_rhs
 
          -- (4) construct representation tycon
-       ; rep_tc_name <- newFamInstTyConName tc_name loc
+       ; rep_tc_name <- newFamInstTyConName tc_name t_typats loc
        ; buildSynTyCon rep_tc_name t_tvs (SynonymTyCon t_rhs) 
                        (typeKind t_rhs) (Just (family, t_typats))
        }}
@@ -337,7 +334,7 @@ tcFamInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
                 newtypeConError tc_name (length k_cons)
 
          -- (4) construct representation tycon
-       ; rep_tc_name <- newFamInstTyConName tc_name loc
+       ; rep_tc_name <- newFamInstTyConName tc_name t_typats loc
        ; let ex_ok = True      -- Existentials ok for type families!
        ; fixM (\ rep_tycon -> do 
             { let orig_res_ty = mkTyConApp fam_tycon t_typats
@@ -693,9 +690,6 @@ tcTyClDecl1 _calc_isrec
   ; idx_tys <- doptM Opt_TypeFamilies
   ; checkTc idx_tys $ badFamInstDecl tc_name
 
-        -- Check for no type indices
-  ; checkTc (not (null tvs)) (noIndexTypes tc_name)
-
   ; tycon <- buildSynTyCon tc_name tvs' (OpenSynTyCon kind Nothing) kind Nothing
   ; return [ATyCon tycon]
   }
@@ -714,9 +708,6 @@ tcTyClDecl1 _calc_isrec
   ; idx_tys <- doptM Opt_TypeFamilies
   ; checkTc idx_tys $ badFamInstDecl tc_name
 
-        -- Check for no type indices
-  ; checkTc (not (null tvs)) (noIndexTypes tc_name)
-
   ; tycon <- buildAlgTyCon tc_name final_tvs [] 
               mkOpenDataTyConRhs Recursive False True Nothing
   ; return [ATyCon tycon]
@@ -1266,12 +1257,19 @@ mkRecSelBind (tycon, sel_name)
     -- Add catch-all default case unless the case is exhaustive
     -- We do this explicitly so that we get a nice error message that
     -- mentions this particular record selector
-    deflt | length cons_w_field == length all_cons = []
+    deflt | not (any is_unused all_cons) = []
          | otherwise = [mkSimpleMatch [nlWildPat] 
                            (nlHsApp (nlHsVar (getName rEC_SEL_ERROR_ID))
                                     (nlHsLit msg_lit))]
 
-    unit_rhs = L loc $ ExplicitTuple [] Boxed
+       -- Do not add a default case unless there are unmatched
+       -- constructors.  We must take account of GADTs, else we
+       -- get overlap warning messages from the pattern-match checker
+    is_unused con = not (con `elem` cons_w_field 
+                        || dataConCannotMatch inst_tys con)
+    inst_tys = tyConAppArgs data_ty
+
+    unit_rhs = mkLHsTupleExpr []
     msg_lit = HsStringPrim $ mkFastString $ 
               occNameString (getOccName sel_name)
 
@@ -1500,11 +1498,6 @@ badSigTyDecl tc_name
           quotes (ppr tc_name)
         , nest 2 (parens $ ptext (sLit "Use -XKindSignatures to allow kind signatures")) ]
 
-noIndexTypes :: Name -> SDoc
-noIndexTypes tc_name
-  = ptext (sLit "Type family constructor") <+> quotes (ppr tc_name)
-    <+> ptext (sLit "must have at least one type index parameter")
-
 badFamInstDecl :: Outputable a => a -> SDoc
 badFamInstDecl tc_name
   = vcat [ ptext (sLit "Illegal family instance for") <+>