error[E0277]: the size for values of type `[u8]` cannot be known at compilation time --> $DIR/ice-6251.rs:4:45 | LL | fn bug() -> impl Iterator { | ^ doesn't have a size known at compile-time | = help: the trait `std::marker::Sized` is not implemented for `[u8]` = help: unsized fn params are gated as an unstable feature help: function arguments must have a statically known size, borrowed types always have a known size | LL | fn bug() -> impl Iterator { | + error[E0277]: the size for values of type `[u8]` cannot be known at compilation time --> $DIR/ice-6251.rs:4:54 | LL | fn bug() -> impl Iterator { | ^ doesn't have a size known at compile-time | = help: the trait `std::marker::Sized` is not implemented for `[u8]` = note: the return type of a function must have a statically known size error[E0308]: mismatched types --> $DIR/ice-6251.rs:4:44 | LL | fn bug() -> impl Iterator { | ^^^^^^^^^^^ expected `usize`, found closure | = note: expected type `usize` found closure `{closure@$DIR/ice-6251.rs:4:44: 4:53}` error: aborting due to 3 previous errors Some errors have detailed explanations: E0277, E0308. For more information about an error, try `rustc --explain E0277`.