In other words the """safe""" stable code looks like this: let mut data = Vec::with_capacity(sz); let mut dst_uninit = data.spare_capacity_mut(); l

In other words the """safe""" stable code looks like this: let mut data = Vec::with_capacity(sz); let mut dst_uninit = data.spare_capacity_mut(); let uninit_src: &[MaybeUninit<T>] = unsafe { transmute(buf) }; dst_uninit.copy_from_slice(uninit_src); unsafe { data.set_len(sz) };