syntax_data: {"ast_node_type":"other","tokens":[{"end":47,"kind":"keyword","start":0,"text":"poly_trait_ref:"}]}
source_snippet:         poly_trait_ref: ty::PolyTraitRef<'tcx>,
context_before:         obligation: &PolyTraitObligation<'tcx>,
context_after:     ) -> Result<PredicateObligations<'tcx>, ()> {