error[E0277]: the size for values of type `[u8]` cannot be known at compilation time --> $DIR/wf-bounds.rs:9:22 | LL | fn nya() -> impl Wf>; | ^^^^^^^^^^^^^ doesn't have a size known at compile-time | = help: the trait `Sized` is not implemented for `[u8]` note: required by a bound in `Vec` --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL | LL | pub struct Vec { | ^ required by this bound in `Vec` error[E0277]: the size for values of type `[u8]` cannot be known at compilation time --> $DIR/wf-bounds.rs:12:23 | LL | fn nya2() -> impl Wf<[u8]>; | ^^^^^^^^ doesn't have a size known at compile-time | = help: the trait `Sized` is not implemented for `[u8]` note: required by a bound in `Wf` --> $DIR/wf-bounds.rs:6:10 | LL | trait Wf {} | ^ required by this bound in `Wf` help: consider relaxing the implicit `Sized` restriction | LL | trait Wf {} | ++++++++ error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0277`.