>Interesting bit of bad code which the compiler does not catch and which causes stack overflow because it is re-entrant:

static void Main(string[] args)
>        {
>            Test test = "Hello World";
>        }
>
>    public class Test
>    {
>        public static implicit operator Test(string s)
>        {
>            return s; // obviously wrong but compiles and is re-entrant when run
>        }
>    }

I think the problem is that the operator does not return an instance of Test

Maybe something like this

	public class Test
	{
		public string Value { get; private set; }
		public Test(string s)
		{
			this.Value = s;
		}
		public static implicit operator Test(string s)
		{
			return new Test(s); // obviously wrong but compiles and is re-entrant when run
		}
	}