_ -> return [(DEFAULT, [], deflt_rhs)]
- | debugIsOn, isAlgTyCon tycon, [] <- tyConDataCons tycon
+ | debugIsOn, isAlgTyCon tycon, not (isOpenTyCon tycon), null (tyConDataCons tycon)
+ -- This can legitimately happen for type families, so don't report that
= pprTrace "prepareDefault" (ppr case_bndr <+> ppr tycon)
- -- This can legitimately happen for type families
$ return [(DEFAULT, [], deflt_rhs)]
--------- Catch-all cases -----------