delegate.cs

using System;
using System.Reflection;
using System.Reflection.Emit;

namespace create_delegate_crash
{
    delegate void Peek<in TRow, TValue>(TRow row, long position, ref TValue value);

    class Foo {
        public string Bar = string.Empty;
    }

    class Program
    {
        static Delegate GeneratePeek<TOwn, TRow, TValue>(FieldInfo fieldInfo, OpCode assignmentOpCode)
        {
            // REVIEW: It seems like we really should cache these, instead of generating them per cursor.
            Type[] args = { typeof(TOwn), typeof(TRow), typeof(long), typeof(TValue).MakeByRefType() };
            var mb = new DynamicMethod("Peek", null, args, typeof(TOwn), true);
            var il = mb.GetILGenerator();

            il.Emit(OpCodes.Ldarg_3);               // push arg3
            il.Emit(OpCodes.Ldarg_1);               // push arg1
            il.Emit(OpCodes.Ldfld, fieldInfo);      // push [stack top].[fieldInfo]
            // Stobj needs to coupled with a type.
            if (assignmentOpCode == OpCodes.Stobj)  // [stack top-1] = [stack top]
                il.Emit(assignmentOpCode, fieldInfo.FieldType);
            else
                il.Emit(assignmentOpCode);
            il.Emit(OpCodes.Ret);                   // ret

            return mb.CreateDelegate(typeof(Peek<TRow, TValue>));
        }

        static void Main(string[] args)
        {
            var foo = new Foo();
            var fieldInfo = foo.GetType().GetField("Bar");
            var peek = GeneratePeek<string, int, Foo>(fieldInfo, OpCodes.Stobj);
            Console.WriteLine(peek);
        }
    }
}