116     Empty(usize),  enumerator
124             inner: Impl::Empty(size),  in new()
130             Impl::Empty(size) => size / 2,  in free_oneway_space()
138             Impl::Empty(_size) => 0,  in count_buffers()
146             Impl::Empty(_size) => Ok(()),  in debug_print()
155             Impl::Empty(size) => {  in reserve_new()
229             Impl::Empty(_size) => Err(EINVAL),  in reservation_abort()
234                     self.inner = Impl::Empty(tree.total_size());  in reservation_abort()
247             Impl::Empty(_size) => Err(EINVAL),  in reservation_commit()
258             Impl::Empty(_size) => Err(EINVAL),  in reserve_existing()
269             Impl::Empty(_size) => {}  in take_for_each()