{"ast_node_type":"variable","tokens":[{"end":67,"kind":"keyword","start":0,"text":"let"}]}
        let upvar_hir_id = upvars[upvar_index].get_root_variable();
    ) -> (Symbol, Span) {
        debug!("get_upvar_name_and_span_for_region: upvar_hir_id={upvar_hir_id:?}");