Fix a bug in the in-scope set that led to some lookupIdSubst errors

diff --git a/compiler/coreSyn/CoreUnfold.lhs b/compiler/coreSyn/CoreUnfold.lhs
index 1ff037f..798d94b 100644 (file)
--- a/compiler/coreSyn/CoreUnfold.lhs
+++ b/compiler/coreSyn/CoreUnfold.lhs
@@ -1181,9 +1181,6 @@ exprIsConApp_maybe id_unf expr
     analyse _ _ = Nothing
 
     -----------
-    in_scope = mkInScopeSet (exprFreeVars expr)
-
-    -----------
     beta (Lam v body) pairs (arg : args) 
         | isTypeArg arg
         = beta body ((v,arg):pairs) args 
@@ -1198,7 +1195,7 @@ exprIsConApp_maybe id_unf expr
            Just ans -> -- pprTrace "Woo-hoo! exprIsConApp_maybe" doc $
                         Just ans
         where
-          subst = mkOpenSubst in_scope pairs
+          subst = mkOpenSubst (mkInScopeSet (exprFreeVars fun)) pairs
          -- doc = vcat [ppr fun, ppr expr, ppr pairs, ppr args]