X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcMType.lhs;h=84fb1b81ede9cce659a7bf3faa03f3218449bbc4;hp=a81270e6c763c3286ef2aaded784c3cb6adb1b79;hb=5de363ca9ebdb7d85e3c353c1cffdf0a1c11128e;hpb=c1e6031c54cda2c6f9fc107eb6cb04ab490f1fef

diff --git a/compiler/typecheck/TcMType.lhs b/compiler/typecheck/TcMType.lhs
index a81270e..84fb1b8 100644
--- a/compiler/typecheck/TcMType.lhs
+++ b/compiler/typecheck/TcMType.lhs
@@ -469,7 +469,7 @@ tcGetGlobalTyVars :: TcM TcTyVarSet
 tcGetGlobalTyVars
   = do { (TcLclEnv {tcl_tyvars = gtv_var}) <- getLclEnv
        ; gbl_tvs  <- readMutVar gtv_var
-       ; gbl_tvs' <- zonkTcTyVarsAndFV (varSetElems gbl_tvs)
+       ; gbl_tvs' <- zonkTcTyVarsAndFV gbl_tvs
        ; writeMutVar gtv_var gbl_tvs'
        ; return gbl_tvs' }
 \end{code}
@@ -480,8 +480,8 @@ tcGetGlobalTyVars
 zonkTcTyVars :: [TcTyVar] -> TcM [TcType]
 zonkTcTyVars tyvars = mapM zonkTcTyVar tyvars
 
-zonkTcTyVarsAndFV :: [TcTyVar] -> TcM TcTyVarSet
-zonkTcTyVarsAndFV tyvars = tyVarsOfTypes <$> mapM zonkTcTyVar tyvars
+zonkTcTyVarsAndFV :: TcTyVarSet -> TcM TcTyVarSet
+zonkTcTyVarsAndFV tyvars = tyVarsOfTypes <$> mapM zonkTcTyVar (varSetElems tyvars)
 
 -----------------  Types
 
@@ -601,12 +601,12 @@ zonkQuantifiedTyVar tv
 
 \begin{code}
 zonkImplication :: Implication -> TcM Implication
-zonkImplication implic@(Implic { ic_env_tvs = env_tvs, ic_given = given 
+zonkImplication implic@(Implic { ic_untch = env_tvs, ic_given = given 
                                , ic_wanted = wanted })
-  = do { env_tvs' <- zonkTcTyVarsAndFV (varSetElems env_tvs)
+  = do { env_tvs' <- zonkTcTyVarsAndFV env_tvs
        ; given'   <- mapM zonkEvVar given
        ; wanted'  <- mapBagM zonkWanted wanted
-       ; return (implic { ic_env_tvs = env_tvs', ic_given = given'
+       ; return (implic { ic_untch = env_tvs', ic_given = given'
                         , ic_wanted = wanted' }) }
 
 zonkEvVar :: EvVar -> TcM EvVar
@@ -1632,14 +1632,12 @@ sizeTypes xs               = sum (map sizeType xs)
 
 -- Size of a predicate
 --
--- Equalities are a special case.  The equality itself doesn't contribute to the
--- size and as we do not count class predicates, we have to start with one less.
--- This is easy to see considering that, given
---   class C a b | a -> b
---   type family F a
--- constraints (C a b) and (F a ~ b) are equivalent in size.
+-- We are considering whether *class* constraints terminate
+-- Once we get into an implicit parameter or equality we
+-- can't get back to a class constraint, so it's safe
+-- to say "size 0".  See Trac #4200.
 sizePred :: PredType -> Int
 sizePred (ClassP _ tys')   = sizeTypes tys'
-sizePred (IParam _ ty)     = sizeType ty
-sizePred (EqPred ty1 ty2)  = sizeType ty1 + sizeType ty2 - 1
+sizePred (IParam {})       = 0
+sizePred (EqPred {})       = 0
 \end{code}