// Compiler options: -langversion:default

public partial class Test
{
	public readonly Foo TheFoo;

	public Test ()
	{
		this.TheFoo = new Foo ();
	}

	public partial interface IFoo
	{
		int Hello (Test foo);
	}

	public int TestFoo ()
	{
		return TheFoo.Hello (this);
	}
}

public partial class Test
{
	public partial class Foo : IFoo
	{
		int IFoo.Hello (Test test)
		{
			return 2;
		}

		public int Hello (Test test)
		{
			return 1;
		}
	}

	public int TestIFoo (IFoo foo)
	{
		return foo.Hello (this);
	}
}

class X
{
	public static int Main ()
	{
		Test test = new Test ();
		if (test.TestFoo () != 1)
			return 1;
		if (test.TestIFoo (test.TheFoo) != 2)
			return 2;
		return 0;
	}
}