Generic implementation for syncing an ICollection with an IEnumerable

CollectionExtensions.cs

namespace System.Linq
{
    public static class CollectionExtensions
    {
        public static void Sync<T>(this ICollection<T> source, IEnumerable<T> other, IEqualityComparer<T>? comparer = null)
        {
            comparer ??= EqualityComparer<T>.Default;

            var itemsToAdd = other.Except(source, comparer);
            var itemsToRemove = source.Except(other, comparer);

            foreach (var item in itemsToAdd)
                source.Add(item);

            foreach (var item in itemsToRemove)
                source.Remove(item);
        }
    }
}