Imported Upstream version 5.12.0.220

Former-commit-id: c477e03582759447177c6d4bf412cd2355aad476

mcs/tests/test-pattern-13.cs

@@ -0,0 +1,19 @@
+using System;
+
+class C : B
+{
+
+}
+
+public class B
+{
+	public static void Main ()
+	{
+		C c = new C ();
+
+		if (c is B b)
+		{
+			Console.WriteLine (b == null);
+		}
+	}
+}