I have some old code which uses Vec::drain_filter a lot. When updated to a newer toolchain, it seems that drain_filter feature is already removed.

I found no explanation about this in rust’s official documents. However, from this post, I found the drain_filter has actually equivalent extract_if. Seems they all accepts some iterator, and filter only the elements which satisfy given predicate.

My question is what makes the difference between drain_filter and extract_if and why we removed drain_filter?