syntax_data: {"ast_node_type":"other","tokens":[{"end":44,"kind":"keyword","start":0,"text":"trait_bound:"}]}
source_snippet:         trait_bound: ty::PolyTraitRef<'tcx>,
context_before:         placeholder_trait_ref: ty::TraitRef<'tcx>,
context_after:     ) -> Result<Option<ty::TraitRef<'tcx>>, ()> {