using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

using System.Runtime.CompilerServices;

using System.Threading.Tasks;

​

class Program

{

    static void Main(string[] args)

    {

        Exception exception = null;

        try

        {

            new Program();

        }

        catch (Exception ex)

        {

            Console.WriteLine(ex);

            exception = ex.Demystify();

        }

​

        Console.WriteLine();

        Console.WriteLine(exception);

    }

​

    static Action<string, bool> s_action = (string s, bool b) => s_func(s, b);

    static Func<string, bool, (string val, bool)> s_func = (string s, bool b) => (RefMethod(s), b);

​

    Action<Action<object>, object> _action = (Action<object> lambda, object state) => lambda(state);

​

    static string s = "";

​

    [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

    Program() : this(() => Start())

    {

​

    }

​

    [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

    Program(Action action) => RunAction((state) => _action((s) => action(), state), null);

​

    [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

    static IEnumerable<string> Iterator(int startAt)

    {

        var list = new List<int>() { 1, 2, 3, 4 };

        foreach (var item in list)

        {

            // Throws the exception

            list.Add(item);

​

            yield return item.ToString();

        }

    }

​

    [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

    static async Task<string> MethodAsync(int value)

    {

        await Task.Delay(0);

        return GenericClass<byte>.GenericMethod(ref value);

    }

​

    [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

    static async Task<string> MethodAsync<TValue>(TValue value)

    {

        return await MethodLocalAsync();

​

        async Task<string> MethodLocalAsync()

        {

            return await MethodAsync(1);

        }

    }

​

    [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

    static void RunAction(Action<object> lambda, object state) => lambda(state);

​

    [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

    static string RunLambda(Func<string> lambda) => lambda();

​

    [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

    static (string val, bool) Method(string value)

    {

#pragma warning disable IDE0039 // Use local function

        Func<string> func = () => MethodAsync(value).GetAwaiter().GetResult();

#pragma warning restore IDE0039 // Use local function

        var anonType = new { func };

        return (RunLambda(() => anonType.func()), true);

    }

​

    [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

    static ref string RefMethod(int value) => ref s;

​

    [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

    static string RefMethod(in string value)

    {

        var val = value;

        return LocalFuncParam(value).ToString();

​

        int LocalFuncParam(string s)

        {

            return int.Parse(LocalFuncRefReturn());

        }

​

        ref string LocalFuncRefReturn()

        {

            Method(val);

            return ref s;

        }

    }

​

    [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

    static string Start()

    {

        return LocalFunc2(true, false).ToString();

​

        void LocalFunc1(long l)

        {

            Start((val: "", true));

        }

​

        bool LocalFunc2(bool b1, bool b2)

        {

            LocalFunc1(1);

            return true;

        }

    }

​

    [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

    static ref string RefMethod(bool value) => ref s;

​

    [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

    static void Start((string val, bool) param) => s_action.Invoke(param.val, param.Item2);

​

​

    class GenericClass<TSuperType>

    {

        [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]

        public static string GenericMethod<TSubType>(ref TSubType value)

        {

            var returnVal = "";

            for (var i = 0; i < 10; i++)

            {

                try

                {

                    returnVal += string.Join(", ", Iterator(5).Select(s => s));

                }

                catch (Exception ex)

                {

                    throw new Exception(ex.Message, ex);

                }

            }

​

            return returnVal;

        }

    }

}