More restrictive assignment from optional<U>

test/optional_test_fail_convert_assign_of_enums.cpp

@@ -0,0 +1,27 @@
+// Copyright (C) 2015, Andrzej Krzemienski.
+//
+// Use, modification, and distribution is subject to the Boost Software
+// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org/lib/optional for documentation.
+//
+// You are welcome to contact the author at:
+//  akrzemi1@gmail.com
+
+#include <iostream>
+#include "boost/optional.hpp"
+
+// THIS TEST SHOULD FAIL TO COMPILE
+
+enum E1 {e1};
+enum E2 {e2};
+
+void test_converitng_assignment_of_different_enums()
+{
+  boost::optional<E2> o2(e2);
+  boost::optional<E1> o1;
+  o1 = o2;
+}
+
+int main() {}