error[E0308]: mismatched types
  --> $DIR/issue-50600.rs:2:13
   |
LL |     fn([u8; |x: u8| {}]),
   |             ^^^^^^^^^^ expected `usize`, found closure
   |
   = note: expected type `usize`
           found closure `{closure@$DIR/issue-50600.rs:2:13: 2:20}`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0308`.