warning: unused return value of `Box::<T>::from_raw` that must be used
  --> $DIR/must-use-box-from-raw.rs:8:5
   |
LL |     Box::from_raw(ptr);
   |     ^^^^^^^^^^^^^^^^^^
   |
   = note: call `drop(Box::from_raw(ptr))` if you intend to drop the `Box`
note: the lint level is defined here
  --> $DIR/must-use-box-from-raw.rs:5:9
   |
LL | #![warn(unused_must_use)]
   |         ^^^^^^^^^^^^^^^
help: use `let _ = ...` to ignore the resulting value
   |
LL |     let _ = Box::from_raw(ptr);
   |     +++++++

warning: 1 warning emitted