{"ast_node_type":"variable","tokens":[{"end":74,"kind":"keyword","start":0,"text":"let"}]}
        let ty::Alias(ty::Projection, future_ty) = return_ty.kind() else {
    if tcx.asyncness(impl_m_def_id).is_async() && tcx.asyncness(trait_m_def_id).is_async() {
            span_bug!(