error[E0700]: hidden type for `impl Debug` captures lifetime that does not appear in bounds --> $DIR/impl-fn-hrtb-bounds-2.rs:5:9 | LL | fn a() -> impl Fn(&u8) -> impl Debug { | ---------- opaque type defined here LL | |x| x | --- ^ | | | hidden type `&u8` captures the anonymous lifetime as defined here error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0700`.