Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

mcs/errors/cs0266-19.cs

@@ -0,0 +1,19 @@
+// CS0266: Cannot implicitly convert type `A' to `B'. An explicit conversion exists (are you missing a cast?)
+// Line: 17
+
+class A
+{
+	public static A operator -- (A x)
+	{
+		return new A ();
+	}
+}
+
+class B : A
+{
+	static void Main ()
+	{
+		B b = new B ();
+		--b;
+	}
+}