Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

mcs/tests/test-744.cs

@@ -0,0 +1,37 @@
+class M
+{
+	sealed class Nested : C
+	{
+		protected override void Extra ()
+		{
+		}
+	}
+	
+	public static void Main ()
+	{
+		new Nested ();
+	}
+}
+
+abstract class A
+{
+	protected abstract void AMethod ();
+}
+
+abstract class B : A
+{
+	protected abstract void BMethod ();
+}
+
+abstract class C : B
+{
+	protected override void AMethod ()
+	{
+	}
+	
+	protected override void BMethod ()
+	{
+	}
+	
+	protected abstract void Extra ();
+}