error[E0277]: the size for values of type `[u8]` cannot be known at compilation time --> $DIR/enum-unit-variant-trait-bound.rs:4:22 | LL | let _ = Option::<[u8]>::None; | ^^^^ doesn't have a size known at compile-time | = help: the trait `Sized` is not implemented for `[u8]` note: required by a bound in `None` --> $SRC_DIR/core/src/option.rs:LL:COL error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0277`.