2 Checks for code to be replaced by `.retain()`.
4 `.retain()` is simpler and avoids needless allocation.
7 let mut vec = vec![0, 1, 2];
8 vec = vec.iter().filter(|&x| x % 2 == 0).copied().collect();
9 vec = vec.into_iter().filter(|x| x % 2 == 0).collect();
13 let mut vec = vec![0, 1, 2];
14 vec.retain(|x| x % 2 == 0);