Function empty_from_raw 

pub unsafe fn empty_from_raw<'a, T>(ptr: *mut [T]) -> OwningSlice<'a, T>

Create an empty OwningSlice<'a, T> from a raw slice pointer. The capacity is the length of the given slice.

Safety

The memory behind ptr must be uniquely borrowed for 'a.

The slice elements are not assumed to be initialized.