like, I do this out of paranoia of accidentally double casting wrong:

```rust
#[cfg(feature = "std")]
impl Storage for BoxedSlice {
    fn ptr_len(&self) -> (NonNull<u8>, usize) {
        let len = self.buf.len();

        let ptr: *const UnsafeCell<MaybeUninit<u8>> = self.buf.as_ptr();
        let ptr: *mut MaybeUninit<u8> = UnsafeCell::raw_get(ptr);
        let ptr: *mut u8 = ptr.cast();
        let nn_ptr = unsafe { NonNull::new_unchecked(ptr) };

        (nn_ptr, len)
    }
}
```