syntax_data: {"ast_node_type":"variable","tokens":[{"end":70,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let r = tcx.type_of(field.did).instantiate(tcx, args);
context_before:             let field_tys = adt_def.all_fields().map(|field| {
context_after:                 debug!(