error[E0507]: cannot move out of captured variable in an `FnMut` closure
  --> $DIR/issue-4335.rs:16:20
   |
LL | fn f<'r, T>(v: &'r T) -> Box<FnMut() -> T + 'r> {
   |             - captured outer variable
LL |     id(Box::new(|| *v))
   |                    ^^ cannot move out of captured variable in an `FnMut` closure

error[E0597]: `v` does not live long enough
  --> $DIR/issue-4335.rs:16:21
   |
LL |     id(Box::new(|| *v))
   |                 --  ^ borrowed value does not live long enough
   |                 |
   |                 value captured here
...
LL | }
   | - `v` dropped here while still borrowed
   |
note: borrowed value must be valid for the lifetime 'r as defined on the function body at 15:6...
  --> $DIR/issue-4335.rs:15:6
   |
LL | fn f<'r, T>(v: &'r T) -> Box<FnMut() -> T + 'r> {
   |      ^^

error: aborting due to 2 previous errors

Some errors occurred: E0507, E0597.
For more information about an error, try `rustc --explain E0507`.