error[E0493]: destructor of `Option<Vec<i32>>` cannot be evaluated at compile-time
  --> $DIR/livedrop.rs:3:9
   |
LL |     let mut always_returned = None;
   |         ^^^^^^^^^^^^^^^^^^^ the destructor for this type cannot be evaluated in constants
...
LL |         always_returned = never_returned;
   |         --------------- value is dropped here

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0493`.