Span does not require local variable assignment. Is that a feature?

Question

I notice that the following will compile and execute even though the local variables are not initialized. Is this a feature of Span?

void Uninitialized()
{
          


        

Answer 1

More or less this is by design, since it depends heavily if the underlying struct holds any fields itself.

This code compiles for example:

public struct MySpan
{
    public int Length => 1;
}

static class Program
{
    static void Main(string[] args)
    {
        MySpan s1;
        var l1 = s1.Length;
    }
}

But this code doesn't:

public struct MySpan
{
    public int Length { get; }
}

static class Program
{
    static void Main(string[] args)
    {
        MySpan s1;
        var l1 = s1.Length;
    }
}

It seems that in that case, the struct is defaulted, and that is why it doesn't complain about a missing assignment. That it doesn't detect any fields is a bug, as explained in Marc's answer.