{"ast_node_type":"impl","tokens":[{"end":78,"kind":"keyword","start":0,"text":"//"}]}
        // contract_check_requires::<C>(C) -> bool, where C: impl Fn() -> bool
        sym::contract_checks => (0, 0, Vec::new(), tcx.types.bool),
        sym::contract_check_requires => (1, 0, vec![param(0)], tcx.types.unit),