+
+{-
+Note [Free-variable space leak]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+We have
+ fvs' = trim fvs
+and we seq fvs' before turning it as part of a record.
+
+The reason is that trim is sometimes something like
+ \xs -> intersectNameSet (mkNameSet bound_names) xs
+and we don't want to retain the list bound_names. This showed up in
+trac ticket #1136.
+-}
+