error[E0277]: expected a `FnOnce<(&mut UIView<'_, T>,)>` closure, found `F` --> $DIR/issue-100690.rs:37:23 | LL | real_dispatch(f) | ------------- ^ expected an `FnOnce<(&mut UIView<'_, T>,)>` closure, found `F` | | | required by a bound introduced by this call | = note: expected a closure with arguments `(&mut UIView<'a, T>,)` found a closure with arguments `(&mut UIView<'_, T>,)` note: required by a bound in `real_dispatch` --> $DIR/issue-100690.rs:9:8 | LL | fn real_dispatch(f: F) -> Result<(), io::Error> | ------------- required by a bound in this ... LL | F: FnOnce(&mut UIView) -> Result<(), io::Error> + Send + 'static, | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `real_dispatch` error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.