error[E0507]: cannot move out of `val`, a captured variable in an `FnMut` closure
  --> $DIR/issue-87456-point-to-closure.rs:10:28
   |
LL |       let val = String::new();
   |           --- captured outer variable
LL |
LL |       take_mut(|| {
   |  ______________-
LL | |
LL | |         let _foo: String = val;
   | |                            ^^^
   | |                            |
   | |                            move occurs because `val` has type `String`, which does not implement the `Copy` trait
   | |                            help: consider borrowing here: `&val`
LL | |
LL | |
LL | |     })
   | |_____- captured by this `FnMut` closure

error: aborting due to previous error

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