ValueTuple: what is wrong with creation of octuple?

Question

ValueTuple as a new feature in C# 7.0 is having public method Create which helps to create ValueTuples (from singleton to octuple or more) on the other hand we can also use new to achieve the same results. I noticed these behave differently. I am trying to research is below implementation wrong or this is something as per design:

Method CreateOctuple() is working as expected:

private static ValueTuple<int, int, int, int, int, int, int, ValueTuple<int>> CreateOctuple()
{
     return new ValueTuple<int, int, int, int, int, int, int, ValueTuple<int>>(1, 2, 3, 4, 5, 6, 7, new ValueTuple<int>(8)); ;
}

Now, I tried to achieve same output using Create() method, unfortunately, it is complaining about the return type:

private static ValueTuple<int, int, int, int, int, int, int, ValueTuple<int>> OctupleUsingCreate()
{
    return ValueTuple.Create(1, 2, 3, 4, 5, 6, 7, ValueTuple.Create(8));
}

What is wrong here?

P.S. All packages are up-to-date and I am using Visual Studio 2017 -latest release.

As suggested by Svick

static ValueTuple<int, int, int, int, int, int, int, ValueTuple<int>> OctupleUsingCreate()
{
  return ValueTuple.Create(1, 2, 3, 4, 5, 6, 7, 8);
}

This prompts same compiler exception:

Answer 1

The issue is that ValueTuple.Create already takes care of calling ValueTuple.Create on the 8th element. So while the correct type for 8-tuple is ValueTuple<int, int, int, int, int, int, int, ValueTuple<int>>, you're creating ValueTuple<int, int, int, int, int, int, int, ValueTuple<ValueTuple<int>>>. The fix is just to remove the second call to ValueTuple.Create:

static ValueTuple<int, int, int, int, int, int, int, ValueTuple<int>> OctupleUsingCreate()
{
    return ValueTuple.Create(1, 2, 3, 4, 5, 6, 7, 8);
}

Or you could just use the tuple syntax, but I'm assuming you have a reason to avoid it:

static (int, int, int, int, int, int, int, int) OctupleUsingCreate()
{
    return (1, 2, 3, 4, 5, 6, 7, 8);
}