Break interned string representation

BreakInternedStringRepresentation.cs

using System;
using System.Runtime.InteropServices;

class Program
{
    [StructLayout(LayoutKind.Explicit)]
    struct Union
    {
        [FieldOffset(0)]
        public string A;

        [FieldOffset(0)]
        public Breaker B;
    }

    class Breaker
    {
        public int Length;
        public char FirstChar;
    }

    static void Main(string[] args)
    {
        var u = new Union();
        u.A = "aaaa";
        u.B.FirstChar = 'b';

        Console.WriteLine("aaaa".StartsWith("a")); // false
    }
}

Wow, I don't even understand what that does :$

It's a hack to mutate the interned string literal using a struct with overlapping object references. It's a known glitch in the .NET Framework