+ -- We need to augment the type variables that appear explicitly in
+ -- the type by those that are determined by the functional dependencies.
+ -- e.g. suppose our type is C a b => a -> a
+ -- with the fun-dep a->b
+ -- Then we should generalise over b too; otherwise it will be
+ -- reported as ambiguous.
+ zonkFunDeps fds `thenNF_Tc` \ fds' ->
+ let tvFundep = tyVarFunDep fds'
+ extended_tyvars = oclose tvFundep body_tyvars
+ in
+ -- pprTrace "gTVTG" (ppr (lie, body_tyvars, extended_tyvars)) $
+ returnNF_Tc (emptyVarSet, extended_tyvars)