Trim imports

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

diff --git a/compiler/typecheck/TcType.lhs b/compiler/typecheck/TcType.lhs
index eaf2faa..50659d5 100644 (file)
--- a/compiler/typecheck/TcType.lhs
+++ b/compiler/typecheck/TcType.lhs
@@ -140,6 +140,7 @@ import ForeignCall
 import Unify
 import VarSet
 import Type
+import Coercion
 import TyCon
 
 -- others:
@@ -840,6 +841,7 @@ tcSplitPredTy_maybe other     = Nothing
 predTyUnique :: PredType -> Unique
 predTyUnique (IParam n _)      = getUnique (ipNameName n)
 predTyUnique (ClassP clas tys) = getUnique clas
+predTyUnique (EqPred a b)      = pprPanic "predTyUnique" (ppr (EqPred a b))
 \end{code}
 
 
@@ -1050,6 +1052,7 @@ exactTyVarsOfType ty
     go (AppTy fun arg)           = go fun `unionVarSet` go arg
     go (ForAllTy tyvar ty)       = delVarSet (go ty) tyvar
                                     `unionVarSet` go_tv tyvar
+    go (NoteTy _ _)              = panic "exactTyVarsOfType"   -- Handled by tcView
 
     go_pred (IParam _ ty)    = go ty
     go_pred (ClassP _ tys)   = exactTyVarsOfTypes tys
@@ -1103,22 +1106,28 @@ restricted set of types as arguments and results (the restricting factor
 being the )
 
 \begin{code}
-tcSplitIOType_maybe :: Type -> Maybe (TyCon, Type)
--- (isIOType t) returns (Just (IO,t')) if t is of the form (IO t'), or
---                                    some newtype wrapping thereof
+tcSplitIOType_maybe :: Type -> Maybe (TyCon, Type, CoercionI)
+-- (isIOType t) returns Just (IO,t',co)
+--                             if co : t ~ IO t'
 --             returns Nothing otherwise
 tcSplitIOType_maybe ty 
-  | Just (io_tycon, [io_res_ty]) <- tcSplitTyConApp_maybe ty,
+  = case tcSplitTyConApp_maybe ty of
        -- This split absolutely has to be a tcSplit, because we must
        -- see the IO type; and it's a newtype which is transparent to splitTyConApp.
-    io_tycon `hasKey` ioTyConKey
-  = Just (io_tycon, io_res_ty)
 
-  | Just ty' <- coreView ty    -- Look through non-recursive newtypes
-  = tcSplitIOType_maybe ty'
+       Just (io_tycon, [io_res_ty]) 
+          |  io_tycon `hasKey` ioTyConKey 
+          -> Just (io_tycon, io_res_ty, IdCo)
 
-  | otherwise
-  = Nothing
+       Just (tc, tys)
+          | not (isRecursiveTyCon tc)
+          , Just (ty, co1) <- instNewTyCon_maybe tc tys
+                 -- Newtypes that require a coercion are ok
+          -> case tcSplitIOType_maybe ty of
+               Nothing             -> Nothing
+               Just (tc, ty', co2) -> Just (tc, ty', co1 `mkTransCoI` co2)
+
+       other -> Nothing
 
 isFFITy :: Type -> Bool
 -- True for any TyCon that can possibly be an arg or result of an FFI call
@@ -1163,13 +1172,11 @@ isFFIDotnetTy dflags ty
        --     it no longer does so.  May need to adjust isFFIDotNetTy
        --     if we do want to look through newtypes.
 
-isFFIDotnetObjTy ty = 
-  let
+isFFIDotnetObjTy ty
+  = checkRepTyCon check_tc t_ty
+  where
    (_, t_ty) = tcSplitForAllTys ty
-  in
-  case tcSplitTyConApp_maybe (repType t_ty) of
-    Just (tc, [arg_ty]) | getName tc == objectTyConName -> True
-    _ -> False
+   check_tc tc = getName tc == objectTyConName
 
 toDNType :: Type -> DNType
 toDNType ty
@@ -1252,7 +1259,11 @@ legalFFITyCon tc
   = isUnLiftedTyCon tc || boxedMarshalableTyCon tc || tc == unitTyCon
 
 marshalableTyCon dflags tc
-  =  (dopt Opt_UnliftedFFITypes dflags && isUnLiftedTyCon tc)
+  =  (dopt Opt_UnliftedFFITypes dflags 
+      && isUnLiftedTyCon tc
+      && case tyConPrimRep tc of       -- Note [Marshalling VoidRep]
+          VoidRep -> False
+          other   -> True)
   || boxedMarshalableTyCon tc
 
 boxedMarshalableTyCon tc
@@ -1267,3 +1278,12 @@ boxedMarshalableTyCon tc
                         , boolTyConKey
                         ]
 \end{code}
+
+Note [Marshalling VoidRep]
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+We don't treat State# (whose PrimRep is VoidRep) as marshalable.
+In turn that means you can't write
+       foreign import foo :: Int -> State# RealWorld
+
+Reason: the back end falls over with panic "primRepHint:VoidRep";
+       and there is no compelling reason to permit it