error[E0382]: use of moved value
  --> $DIR/move-in-pattern-mut-in-loop.rs:7:21
   |
LL |         if let Some(mut _x) = opt {}
   |                     ^^^^^^ value moved here, in previous iteration of loop
   |
   = note: move occurs because value has type `&mut i32`, which does not implement the `Copy` trait
help: borrow this field in the pattern to avoid moving `opt.0`
   |
LL |         if let Some(ref mut _x) = opt {}
   |                     +++

error: aborting due to previous error

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