Fix recursive superclasses (again). Fixes Trac #4809.

[ghc-hetmet.git] / compiler / coreSyn / CoreSubst.lhs

diff --git a/compiler/coreSyn/CoreSubst.lhs b/compiler/coreSyn/CoreSubst.lhs
index 346f78f..a229b8c 100644 (file)
--- a/compiler/coreSyn/CoreSubst.lhs
+++ b/compiler/coreSyn/CoreSubst.lhs
@@ -574,7 +574,9 @@ substUnfoldingSC subst unf   -- Short-cut version
   | otherwise          = substUnfolding subst unf
 
 substUnfolding subst (DFunUnfolding ar con args)
-  = DFunUnfolding ar con (map (substExpr (text "dfun-unf") subst) args)
+  = DFunUnfolding ar con (map subst_arg args)
+  where
+    subst_arg = fmap (substExpr (text "dfun-unf") subst)
 
 substUnfolding subst unf@(CoreUnfolding { uf_tmpl = tmpl, uf_src = src })
        -- Retain an InlineRule!