{"ast_node_type":"variable","tokens":[{"end":51,"kind":"keyword","start":0,"text":"let"}]}
                let callee_ty = func.ty(body, tcx);
            | mir::TerminatorKind::TailCall { ref func, ref fn_span, .. } => {
                let callee_ty = instance.instantiate_mir_and_normalize_erasing_regions(