{"ast_node_type":"variable","tokens":[{"end":62,"kind":"keyword","start":0,"text":"if"}]}
    if let Err(err) = check_constraints(tcx, def_id, sig_id) {
    let caller_sig = tcx.fn_sig(sig_id);
        let sig_len = caller_sig.instantiate_identity().skip_binder().inputs().len() + 1;