pub fn as_ptr(this: &Self) -> *const T {
        let ptr: *mut RcBox<T> = NonNull::as_ptr(this.ptr);

        // SAFETY: This cannot go through Deref::deref or Rc::inner because
        // this is required to retain raw/mut provenance such that e.g. `get_mut` can
        // write through the pointer after the Rc is recovered through `from_raw`.
        unsafe { ptr::addr_of_mut!((*ptr).value) }
    }
Gets the number of [`Weak`] pointers to this allocation.

# Exam
benchmarks/haystacks/code/rust-library.rs