syntax_data: {"ast_node_type":"variable","tokens":[{"end":95,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let source = self.infcx.shallow_resolve(obligation.self_ty().no_bound_vars().unwrap());
context_before:         // regions here. See the comment there for more details.
context_after:         let target = obligation.predicate.skip_binder().trait_ref.args.type_at(1);