error: boxed return of the sized type `[u8; 64]`
  --> $DIR/unnecessary_box_returns.rs:3:11
   |
LL | fn f() -> Box<[u8; 64]> {
   |           ^^^^^^^^^^^^^ help: try: `[u8; 64]`
   |
   = help: changing this also requires a change to the return expressions in this function
   = note: `-D clippy::unnecessary-box-returns` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(clippy::unnecessary_box_returns)]`

error: aborting due to 1 previous error