using System;

using System.IO;

using System.Reflection;

using Mono.Cecil;

using FieldAttributes = Mono.Cecil.FieldAttributes;

​

namespace CoreCecil

{

    class Program

    {

        static void Main(string[] args)

        {

            var asmDef = AssemblyDefinition.ReadAssembly(typeof(SomeType).Module.FullyQualifiedName);

            asmDef.Name.Name += "Fake";

            var typeDef = asmDef.MainModule.GetType(typeof(SomeType).FullName);

            var fieldDef = new FieldDefinition("TestField", FieldAttributes.Public, asmDef.MainModule.ImportReference(typeof(Test)));

            typeDef.Fields.Add(fieldDef);

​

            var mem = new MemoryStream();

            asmDef.Write(mem);

            var asm = Assembly.Load(mem.ToArray());

            var type = asm.GetType(typeof(SomeType).FullName);

            var field = type.GetField("TestField");

            Console.WriteLine(fieldDef.FieldType.Module.FullyQualifiedName);

            Console.WriteLine(field.FieldType.Module.FullyQualifiedName);

        }

    }

​

    public class SomeType

    {

​

    }

​

    public class Test

    {

        public int X { get; set; }

    }

}

​