[project @ 2003-12-17 11:29:40 by simonpj]

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

diff --git a/ghc/compiler/typecheck/TcBinds.lhs b/ghc/compiler/typecheck/TcBinds.lhs
index bfa394b..6a66814 100644 (file)
--- a/ghc/compiler/typecheck/TcBinds.lhs
+++ b/ghc/compiler/typecheck/TcBinds.lhs
@@ -592,8 +592,8 @@ checkSigsTyVars qtvs sigs
        --      f () = ()
        -- Here, 'a' won't appear in qtvs, so we have to add it
 
-       sig_tvs = foldr (unionVarSet . mkVarSet) emptyVarSet sig_tvs_s
-       all_tvs = mkVarSet qtvs `unionVarSet` sig_tvs
+       sig_tvs = foldl extendVarSetList emptyVarSet sig_tvs_s
+       all_tvs = extendVarSetList sig_tvs qtvs
     in
     returnM (varSetElems all_tvs)
   where