Function query_feed 

pub(crate) fn query_feed<'tcx, C>(
    tcx: TyCtxt<'tcx>,
    query: &'tcx QueryVTable<'tcx, C>,
    key: C::Key,
    value: C::Value,
)
where
    C: QueryCache,
    C::Key: DepNodeKey<'tcx>,

“Feeds” a feedable query by adding a given key/value pair to its in-memory cache. Called by macro-generated methods of rustc_middle::ty::TyCtxtFeed.