error[E0277]: the size for values of type `[Box]` cannot be known at compilation time --> $DIR/issue-35988.rs:2:7 | LL | V([Box]), | ^^^^^^^^ doesn't have a size known at compile-time | = help: the trait `Sized` is not implemented for `[Box]` = 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]), | + help: the `Box` type always has a statically known size and allocates its contents in the heap | LL | V(Box<[Box]>), | ++++ + error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0277`.