error[E0382]: use of moved value: `y`
  --> $DIR/liveness-move-in-loop.rs:11:25
   |
LL |     let y: Box<isize> = 42.into();
   |         - move occurs because `y` has type `Box<isize>`, which does not implement the `Copy` trait
...
LL |     loop {
   |     ---- inside of this loop
LL |         println!("{}", y);
LL |         loop {
   |         ---- inside of this loop
LL |             loop {
   |             ---- inside of this loop
LL |                 loop {
   |                 ---- inside of this loop
LL |                     x = y;
   |                         ^ value moved here, in previous iteration of loop
   |
help: consider cloning the value if the performance cost is acceptable
   |
LL |                     x = y.clone();
   |                          ++++++++

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0382`.