Correct substitution into theta types (after merge)

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

diff --git a/compiler/typecheck/TcPat.lhs b/compiler/typecheck/TcPat.lhs
index f165e2e..3ebb7b7 100644 (file)
--- a/compiler/typecheck/TcPat.lhs
+++ b/compiler/typecheck/TcPat.lhs
@@ -21,6 +21,7 @@ import Inst           ( InstOrigin(..), shortCutFracLit, shortCutIntLit,
                          newDictBndrs, instToId, instStupidTheta, isHsVar
                        )
 import Id              ( Id, idType, mkLocalId )
+import Var             ( CoVar )
 import CoreFVs         ( idFreeTyVars )
 import Name            ( Name, mkSystemVarName )
 import TcSimplify      ( tcSimplifyCheck, bindInstsOfLocalFuns )
@@ -28,14 +29,15 @@ import TcEnv                ( newLocalName, tcExtendIdEnv1, tcExtendTyVarEnv2,
                          tcLookupClass, tcLookupDataCon, refineEnvironment,
                          tcLookupField, tcMetaTy )
 import TcMType                 ( newFlexiTyVarTy, arityErr, tcInstSkolTyVars, 
-                         newCoVars, zonkTcType, tcInstTyVars )
+                         newCoVars, zonkTcType, tcInstTyVars, newBoxyTyVar )
 import TcType          ( TcType, TcTyVar, TcSigmaType, TcRhoType, BoxyType,
                          SkolemInfo(PatSkol), 
                          BoxySigmaType, BoxyRhoType, argTypeKind, typeKind,
                          pprSkolTvBinding, isRigidTy, tcTyVarsOfTypes, 
-                         zipTopTvSubst, isArgTypeKind, isUnboxedTupleType,
+                         zipTopTvSubst, isSubArgTypeKind, isUnboxedTupleType,
                          mkTyVarTys, mkClassPred, isOverloadedTy, substEqSpec,
-                         mkFunTy, mkFunTys, tidyOpenType, tidyOpenTypes )
+                         mkFunTy, mkFunTys, tidyOpenType, tidyOpenTypes,
+                         mkTyVarTy )
 import VarSet          ( elemVarSet )
 import {- Kind parts of -} 
        Type            ( liftedTypeKind )
@@ -44,10 +46,11 @@ import TcUnify              ( boxySplitTyConApp, boxySplitListTy, unBox,
                          checkSigTyVarsWrt, unifyType )
 import TcHsType                ( UserTypeCtxt(..), tcPatSig )
 import TysWiredIn      ( boolTy, parrTyCon, tupleTyCon )
+import TcGadt          ( Refinement, emptyRefinement, gadtRefine, refineType )
 import Type            ( Type, mkTyConApp, substTys, substTheta )
 import StaticFlags     ( opt_IrrefutableTuples )
 import TyCon           ( TyCon, FieldLabel, tyConFamInst_maybe,
-                         tyConFamilyCoercion_maybe, tyConTyVars )
+                         tyConFamilyCoercion_maybe, tyConTyVars, isNewTyCon )
 import DataCon         ( DataCon, dataConTyCon, dataConFullSig, dataConName,
                          dataConFieldLabels, dataConSourceArity, 
                          dataConStupidTheta, dataConUnivTyVars )
@@ -227,7 +230,7 @@ unBoxArgType ty pp_this
        -- but they improve error messages, and allocate fewer tyvars
        ; if isUnboxedTupleType ty' then
                failWithTc msg
-         else if isArgTypeKind (typeKind ty') then
+         else if isSubArgTypeKind (typeKind ty') then
                return ty'
          else do       -- OpenTypeKind, so constrain it
        { ty2 <- newFlexiTyVarTy argTypeKind
@@ -586,6 +589,7 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside
     -- representation tycon.
     --
     boxySplitTyConAppWithFamily tycon pat_ty =
+      traceTc traceMsg >>
       case tyConFamInst_maybe tycon of
         Nothing                   -> boxySplitTyConApp tycon pat_ty
        Just (fam_tycon, instTys) -> 
@@ -594,6 +598,12 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside
             ; boxyUnifyList (substTys subst instTys) scrutinee_arg_tys
             ; return freshTvs
             }
+      where
+        traceMsg = sep [ text "tcConPat:boxySplitTyConAppWithFamily:" <+>
+                        ppr tycon <+> ppr pat_ty
+                      , text "  family instance:" <+> 
+                        ppr (tyConFamInst_maybe tycon)
+                       ]
 
     -- Wraps the pattern (which must be a ConPatOut pattern) in a coercion
     -- pattern if the tycon is an instance of a family.
@@ -601,6 +611,8 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside
     unwrapFamInstScrutinee :: TyCon -> [Type] -> Pat Id -> Pat Id
     unwrapFamInstScrutinee tycon args pat
       | Just co_con <- tyConFamilyCoercion_maybe tycon 
+--      , not (isNewTyCon tycon)       -- newtypes are explicitly unwrapped by
+                                    -- the desugarer
           -- NB: We can use CoPat directly, rather than mkCoPat, as we know the
           --    coercion is not the identity; mkCoPat is inconvenient as it
           --    wants a located pattern.