{"ast_node_type":"variable","tokens":[{"end":39,"kind":"keyword","start":0,"text":"let"}]}
        let rule = &self.rules[rule_i];
        // If the rhs contains an invocation like `compile_error!`, don't report it as unused.
        if has_compile_error_macro(&rule.rhs) { None } else { Some((&self.name, rule.lhs_span)) }