error: unused closure that must be used
  --> $DIR/unused-closure.rs:9:5
   |
LL | /     || {
LL | |         println!("Hello!");
LL | |     };
   | |______^
   |
note: the lint level is defined here
  --> $DIR/unused-closure.rs:6:9
   |
LL | #![deny(unused_must_use)]
   |         ^^^^^^^^^^^^^^^
   = note: closures are lazy and do nothing unless called

error: unused implementer of `Future` that must be used
  --> $DIR/unused-closure.rs:13:5
   |
LL |     async {};
   |     ^^^^^^^^^
   |
   = note: futures do nothing unless you `.await` or poll them

error: unused closure that must be used
  --> $DIR/unused-closure.rs:14:5
   |
LL |     || async {};
   |     ^^^^^^^^^^^^
   |
   = note: closures are lazy and do nothing unless called

error: unused closure that must be used
  --> $DIR/unused-closure.rs:15:5
   |
LL |     async || {};
   |     ^^^^^^^^^^^^
   |
   = note: closures are lazy and do nothing unless called

error: unused array of boxed arrays of closures that must be used
  --> $DIR/unused-closure.rs:18:5
   |
LL |     [Box::new([|| {}; 10]); 1];
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: closures are lazy and do nothing unless called

error: unused closure that must be used
  --> $DIR/unused-closure.rs:20:5
   |
LL |     vec![|| "a"].pop().unwrap();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: closures are lazy and do nothing unless called

error: unused closure that must be used
  --> $DIR/unused-closure.rs:23:9
   |
LL |         || true;
   |         ^^^^^^^^
   |
   = note: closures are lazy and do nothing unless called

error: aborting due to 7 previous errors