Automatic Properties and Structs

I was merrily creating my first struct since the advent of automatic properties and figured it would be nice and easy, so continued and created the following:

public struct UserNamePasswordPair
    {
        public string UserName { get; set; }
        public string Password { get; set; }

        public UserNamePasswordPair(string userName, string password)
        {
            UserName = userName;
            Password = password;
        }
    }

To my disappointment I got a compiler error:

"The 'this' object cannot be used before all of its fields are assigned to"

This was very disappointing and I thought surely Microsoft wouldn't have forgotten to allow automatic properties on structs and it turns out they haven't, looking further down the error list I see a useful message:

"Backing field for automatically implemented property 'UserNamePasswordPair.UserName' must be fully assigned before control is returned to the caller. Consider calling the default constructor from a constructor initializer."

Ah ha, fair enough, so I simply added the call to the default constructor and bobs you uncle it compiled, yeh!

public struct UserNamePasswordPair
    {
        public string UserName { get; set; }
        public string Password { get; set; }

        public UserNamePasswordPair(string userName, string password)
               : this()
        {
            UserName = userName;
            Password = password;
        }
    }