error: unreachable pattern
  --> $DIR/uninhabited-patterns.rs:30:9
   |
LL |         Ok(box _) => (),
   |         ^^^^^^^^^
   |
note: the lint level is defined here
  --> $DIR/uninhabited-patterns.rs:4:9
   |
LL | #![deny(unreachable_patterns)]
   |         ^^^^^^^^^^^^^^^^^^^^

error: unreachable pattern
  --> $DIR/uninhabited-patterns.rs:39:9
   |
LL |         Err(Ok(_y)) => (),
   |         ^^^^^^^^^^^

error: unreachable pattern
  --> $DIR/uninhabited-patterns.rs:42:15
   |
LL |     while let Some(_y) = foo() {
   |               ^^^^^^^^

error: aborting due to 3 previous errors