X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcImprove.lhs;h=9093ccbbb8957ee86b4e7b525836f2f5928dfe3a;hb=fe69f3c1d6062b90635963aa414c33951bf18427;hp=7ba6d21327da9aebb92411cb4e90c89d6f7a1810;hpb=7185a7c33692e7b8f01a6557a34d68225501e54b;p=ghc-hetmet.git

diff --git a/ghc/compiler/typecheck/TcImprove.lhs b/ghc/compiler/typecheck/TcImprove.lhs
index 7ba6d21..9093ccb 100644
--- a/ghc/compiler/typecheck/TcImprove.lhs
+++ b/ghc/compiler/typecheck/TcImprove.lhs
@@ -6,7 +6,7 @@ module TcImprove ( tcImprove ) where
 import Name		( Name )
 import Class		( Class, FunDep, className, classExtraBigSig )
 import Unify		( unifyTyListsX, matchTys )
-import Subst		( mkSubst, substTy )
+import Subst		( mkSubst, emptyInScopeSet, substTy )
 import TcEnv		( tcGetInstEnv, classInstEnv )
 import TcMonad
 import TcType		( TcType, TcTyVar, TcTyVarSet, zonkTcType, zonkTcTypes )
@@ -104,8 +104,9 @@ checkFd free (t_x, t_y) (s_x, s_y)
   = zonkUnifyTys free t_x s_x `thenTc` \ msubst ->
     case msubst of
       Just subst ->
-	let t_y' = map (substTy (mkSubst emptyVarEnv subst)) t_y
-	    s_y' = map (substTy (mkSubst emptyVarEnv subst)) s_y
+	let full_subst = mkSubst emptyInScopeSet subst
+  	    t_y' = map (substTy full_subst) t_y
+	    s_y' = map (substTy full_subst) s_y
 	in
 	    zonkEqTys t_y' s_y' `thenTc` \ eq ->
 	    if eq then