{"ast_node_type":"variable","tokens":[{"end":100,"kind":"keyword","start":0,"text":"let"}]}
        let guar = cx.dcx().emit_err(errors::ConcatBytesMissingLiteral { spans: missing_literals });
    ExpandResult::Ready(if !missing_literals.is_empty() {
        MacEager::expr(DummyResult::raw_expr(sp, Some(guar)))