error[E0277]: the size for values of type `[u8]` cannot be known at compilation time
  --> $DIR/issue-30355.rs:5:8
   |
LL |     &X(*Y)
   |      - ^^ doesn't have a size known at compile-time
   |      |
   |      required by a bound introduced by this call
   |
   = help: the trait `Sized` is not implemented for `[u8]`
   = help: unsized fn params are gated as an unstable feature
help: function arguments must have a statically known size, borrowed types always have a known size
   |
LL |     &X(&*Y)
   |        +

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.