using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Reflection;

​

namespace Console2017.Mains

{

    static class MapToCollection

    {

        static public object LateCast(this ICollection items, Type itemType)

        {

            var methodDefintionForCast = typeof(System.Linq.Enumerable)

                .GetMethods(BindingFlags.Static | BindingFlags.Public)

                .Where(mi => mi.Name == "Cast")

                .Select(mi => mi.GetGenericMethodDefinition())

                .Single(gmd => gmd != null && gmd.GetGenericArguments().Length == 1);

​

            var method = methodDefintionForCast.MakeGenericMethod(new Type[] { itemType });

            return method.Invoke(null, new[] { items });

        }

​

​

        static public IEnumerable ConvertToGeneric(this ICollection source, Type collectionType)

        {

            return source.LateCast(collectionType.GetGenericArguments()[0]) as IEnumerable;

        }

    }

​

    public class Program

    {

        public void Main()

        {

            var input = new LinkedList<string>();

            input.AddFirst("Test1");

            input.AddLast("Test2");

            object output = input.ConvertToGeneric(typeof(ICollection<string>));

​

            foreach (var item in output as IEnumerable) Console.WriteLine("Here it is: {0}", item);

        }

    }

}

​