Imported Upstream version 4.2.0.179

Former-commit-id: 0a113cb3a6feb7873f632839b1307cc6033cd595

mcs/errors/cs9030-2.cs

@@ -0,0 +1,17 @@
+// CS9030: The left-hand side of an assignment cannot contain a null propagating operator
+// Line: 15
+
+public class Test1
+{
+	public class Test2
+	{
+		public System.EventHandler<System.EventArgs> E;
+	}
+
+	public Test2 test2 = new Test2 ();
+
+	static void Main ()
+	{
+		new Test1 ()?.test2.E += null;
+	}
+}