error[E0493]: destructor of `Option<T>` cannot be evaluated at compile-time
  --> $DIR/precise-drop-allow-const-fn-unstable.rs:11:24
   |
LL | pub const fn unwrap<T>(this: Option<T>) -> T {
   |                        ^^^^ the destructor for this type cannot be evaluated in constant functions
...
LL | }
   | - value is dropped here

error: aborting due to 1 previous error

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