syntax_data: {"ast_node_type":"variable","tokens":[{"end":95,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let mut visitor = RPITVisitor { tcx, synthetics: vec![], data, disambiguator };
context_before:                 let data = DefPathData::AnonAssocTy(def_name);
context_after:                 visitor.visit_fn_ret_ty(output);