GuidUnion

/// <summary>
/// Structure spéciale permettant de "fusionner" les deux structures <see cref="Guid"/> et <see cref="ExposedGuid"/>
/// en les superposant.
/// </summary> 
/// <remarks>
/// Cette structure permet ainsi de modifier la valeur des champs de <see cref="Guid"/> en passant par
/// <see cref="P:ExposedGuid"/>, alors que ceci ne devrait pas être possible.
/// </remarks>
[StructLayout(LayoutKind.Explicit)]
private struct Union
{
    public Union(Guid guid)
    {
        this.ExposedGuid = new ExposedGuid();
        this.Guid = guid;
    }

    /// <summary>
    /// Instance du <see cref="T:Guid"/> à modifier.
    /// </summary>
    [FieldOffset(0)]
    public Guid Guid;

    /// <summary>
    /// Instance de <see cref="ExposedGuid"/> permettant de modifier la valeur des champs.
    /// </summary>
    [FieldOffset(0)]
    public ExposedGuid ExposedGuid;
}

/// <summary>
/// Expose la structure de <see cref="Guid"/> au travers de champs publics.
/// </summary>
private struct ExposedGuid
{
#pragma warning disable 169
#pragma warning disable 649
    // ReSharper disable InconsistentNaming
    public int _a;
    public short _b;
    public short _c;
    public byte _d;
    public byte _e;
    public byte _f;
    public byte _g;
    public byte _h;
    public byte _i;
    public byte _j;
    public byte _k;
    // ReSharper restore InconsistentNaming
#pragma warning restore 649
#pragma warning restore 169
}