error[E0277]: the size for values of type `[Box<E>]` cannot be known at compilation time
  --> $DIR/issue-35988.rs:2:7
   |
LL |     V([Box<E>]),
   |       ^^^^^^^^ doesn't have a size known at compile-time
   |
   = help: the trait `Sized` is not implemented for `[Box<E>]`
   = note: no field of an enum variant may have a dynamically sized type
   = help: change the field's type to have a statically known size
help: borrowed types always have a statically known size
   |
LL |     V(&[Box<E>]),
   |       +
help: the `Box` type always has a statically known size and allocates its contents in the heap
   |
LL |     V(Box<[Box<E>]>),
   |       ++++        +

error: aborting due to 1 previous error

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