error[E0277]: the size for values of type `[u8]` cannot be known at compilation time --> $DIR/wf-bounds.rs:14:22 | LL | fn nya() -> impl Wf<Vec<[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 `Vec` --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL error[E0277]: the size for values of type `[u8]` cannot be known at compilation time --> $DIR/wf-bounds.rs:17:23 | 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:7:10 | LL | trait Wf<T> { | ^ required by this bound in `Wf` help: consider relaxing the implicit `Sized` restriction | LL | trait Wf<T: ?Sized> { | ++++++++ error[E0277]: the size for values of type `[u8]` cannot be known at compilation time --> $DIR/wf-bounds.rs:20:44 | LL | fn nya3() -> impl Wf<(), Output = impl Wf<Vec<[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 `Vec` --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL error[E0277]: `T` doesn't implement `std::fmt::Display` --> $DIR/wf-bounds.rs:23:26 | LL | fn nya4<T>() -> impl Wf<NeedsDisplay<T>>; | ^^^^^^^^^^^^^^^^^^^ `T` cannot be formatted with the default formatter | = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead note: required by a bound in `NeedsDisplay` --> $DIR/wf-bounds.rs:11:24 | LL | struct NeedsDisplay<T: Display>(T); | ^^^^^^^ required by this bound in `NeedsDisplay` error: aborting due to 4 previous errors For more information about this error, try `rustc --explain E0277`.