error[E0507]: cannot move out of `x`, a captured variable in an `Fn` closure
  --> $DIR/unboxed-closure-illegal-move.rs:15:31
   |
LL |         let x = Box::new(0);
   |             - captured outer variable
LL |         let f = to_fn(|| drop(x));
   |                       --      ^ move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
   |                       |
   |                       captured by this `Fn` closure
   |
help: consider cloning the value if the performance cost is acceptable
   |
LL |         let f = to_fn(|| drop(x.clone()));
   |                                ++++++++

error[E0507]: cannot move out of `x`, a captured variable in an `FnMut` closure
  --> $DIR/unboxed-closure-illegal-move.rs:19:35
   |
LL |         let x = Box::new(0);
   |             - captured outer variable
LL |         let f = to_fn_mut(|| drop(x));
   |                           --      ^ move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
   |                           |
   |                           captured by this `FnMut` closure
   |
help: consider cloning the value if the performance cost is acceptable
   |
LL |         let f = to_fn_mut(|| drop(x.clone()));
   |                                    ++++++++

error[E0507]: cannot move out of `x`, a captured variable in an `Fn` closure
  --> $DIR/unboxed-closure-illegal-move.rs:28:36
   |
LL |         let x = Box::new(0);
   |             - captured outer variable
LL |         let f = to_fn(move || drop(x));
   |                       -------      ^ move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
   |                       |
   |                       captured by this `Fn` closure

error[E0507]: cannot move out of `x`, a captured variable in an `FnMut` closure
  --> $DIR/unboxed-closure-illegal-move.rs:32:40
   |
LL |         let x = Box::new(0);
   |             - captured outer variable
LL |         let f = to_fn_mut(move || drop(x));
   |                           -------      ^ move occurs because `x` has type `Box<i32>`, which does not implement the `Copy` trait
   |                           |
   |                           captured by this `FnMut` closure

error: aborting due to 4 previous errors

For more information about this error, try `rustc --explain E0507`.