Resolved: Copy slice into its own array

Question:

I want to copy the values at one slice of an array into another slice.
The obvious way (using iteration) is:
However, that seems rather inefficient.
The usual way to copy a slice:
does not work as arr is borrowed twice.
The only other way to do this that comes to mind is std::ptr::copy_nonoverlapping, which is unsafe.
What is the best way to copy a slice into its own array (while knowing that source and destination do not overlap)?

Answer:

Using copy_within():
Note that it does not require them to not overlap.
If you’re sure they do not overlap, and you want to exploit that, you can use unsafe code:

If you have better answer, please add a comment about this, thank you!