Many types in the standard library do not consider it sound behavior to have their allocations freed by functions other than their own destructors: https://doc

Many types in the standard library do not consider it sound behavior to have their allocations freed by functions other than their own destructors: https://doc.rust-lang.org/std/boxed/struct.Box.html#method.into_raw https://doc.rust-lang.org/std/boxed/struct.Box.html#method.i... After calling this function, the caller is responsible for the memory previously managed by the Box. In particular, the caller should properly destroy T and release the memory. The proper way to do so is to convert the NonNull<T> pointer into a raw pointer and back into a Box with the Box::from_raw function. I would guess that this might become a fun latent footgun in crates.io code -- everyone writes their unsafe code in a way that Just Works under the default allocator, but then things break down in confusing ways when enabling alternative allocators, which should be safe to do even when using external crates.