gistfile1.txt

using System;
using System.Text;

class Test
{
    // Notes:
    // The target of the builder.Length assignment is evaluated before
    // any of the assignments actually happen - in particular, before the
    // builder assignment from the first element of the tuple.
    //
    // In the Reflector-decompiled code, the new value of builder is
    // used, so the original StringBuilder isn't truncated.

    static void Main()
    {
        StringBuilder builder = new StringBuilder("123456789");
        StringBuilder original = builder;
        (builder, builder.Length) = (new StringBuilder(), 5);
        Console.WriteLine(original); // Prints 12345
    }
    
    private static void MainAsDecompiledInReflector9_0_2_546()
    {
        StringBuilder builder = new StringBuilder("123456789");
        StringBuilder builder2 = builder;
        ValueTuple<StringBuilder, int> tuple1 = new ValueTuple<StringBuilder, int>(new StringBuilder(), 5);
        StringBuilder builder3 = tuple1.Item1;
        int num = tuple1.Item2;
        builder = builder3;
        builder.Length = num;
        Console.WriteLine(builder2); // Prints 123456789
    }
}