message: TODO cleanup: remove an unnecessary `#[allow(unused)]`.
diff: @@ -99,7 +99,6 @@ impl Upcall {
  pub(crate) type UpcallQueue = std::collections::VecDeque<crate::upcall::UpcallQueueEntry>;
  // An entry in the fake kernel's upcall queue.
  -#[allow(dead_code)] // TODO: Remove when upcall invocation is implemented in Yield.
  pub(crate) struct UpcallQueueEntry {
  pub args: (u32, u32, u32),
  pub id: UpcallId,
  