syntax_data: {"ast_node_type":"variable","tokens":[{"end":95,"kind":"keyword","start":0,"text":"ty::Alias(ty::Free,"}]}
source_snippet:             ty::Alias(ty::Free, alias_ty) if let Some(def_id) = alias_ty.def_id.as_local() => {
context_before:             // FIXME(type_alias_impl_trait): can we require mentioning nested type aliases explicitly?
context_after:                 if !self.seen.insert(def_id) {