fn wait_for_query<Q, Qcx>(
    query: Q,
    qcx: Qcx,
    span: Span,
    key: Q::Key,
    latch: QueryLatch,
    current: Option<QueryJobId>
) -> (Q::Value, Option<DepNodeIndex>)
where Q: QueryConfig<Qcx>, Qcx: QueryContext,