{"ast_node_type":"variable","tokens":[{"end":97,"kind":"keyword","start":0,"text":"let"}]}
    let (live_symbols, ignored_derived_traits) = tcx.live_symbols_and_ignored_derived_traits(());
fn check_mod_deathness(tcx: TyCtxt<'_>, module: LocalModDefId) {
    let mut visitor = DeadVisitor { tcx, live_symbols, ignored_derived_traits };