{"ast_node_type":"other","tokens":[{"end":31,"kind":"keyword","start":0,"text":"Some(_bad_feature)"}]}
        Some(_bad_feature) => {
        Some(feature) if rustc_lexer::is_ident(feature.as_str()) => Ok(feature),
            Err(cx.emit_err(session_diagnostics::NonIdentFeature { span: cx.attr_span }))