is_local name = nameIsLocalOrFrom mod name
-- Compute orphanhood. See Note [Orphans] in IfaceSyn
- (_, cls, tys) = tcSplitDFunTy (idType dfun_id)
+ (_, _, cls, tys) = tcSplitDFunTy (idType dfun_id)
-- Slightly awkward: we need the Class to get the fundeps
(tvs, fds) = classTvsFds cls
arg_names = [filterNameSet is_local (tyClsNamesOfType ty) | ty <- tys]