Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

mcs/tests/gtest-294.cs

@@ -0,0 +1,31 @@
+class A {}
+class B : A {}
+
+class X
+{
+	public static A Test (A a, B b)
+	{
+		return b ?? a;
+	}
+
+	public static int Main ()
+	{
+		A a = new A ();
+		B b = new B ();
+
+		if (Test (a, b) != b)
+			return 1;
+
+		if (Test (null, b) != b)
+			return 2;
+
+		if (Test (a, null) != a)
+			return 3;
+
+		if (Test (null, null) != null)
+			return 4;
+
+		return 0;
+
+	}
+}