1 files changed, 268 insertions, 0 deletions
diff --git a/test/std/utilities/optional/optional.object/optional.object.assign/optional_U.pass.cpp b/test/std/utilities/optional/optional.object/optional.object.assign/optional_U.pass.cpp
new file mode 100644
index 000000000000..db7fc19bfb10
--- /dev/null
+++ b/test/std/utilities/optional/optional.object/optional.object.assign/optional_U.pass.cpp
@@ -0,0 +1,268 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+// <optional>
+
+// From LWG2451:
+// template <class U>
+// optional<T>& operator=(optional<U>&& rhs);
+
+#include <optional>
+#include <type_traits>
+#include <memory>
+#include <cassert>
+
+#include "test_macros.h"
+#include "archetypes.hpp"
+
+using std::optional;
+
+struct X
+{
+    static bool throw_now;
+
+    X() = default;
+    X(int &&)
+    {
+        if (throw_now)
+            TEST_THROW(6);
+    }
+};
+
+bool X::throw_now = false;
+
+struct Y1
+{
+    Y1() = default;
+    Y1(const int&) {}
+    Y1& operator=(const Y1&) = delete;
+};
+
+struct Y2
+{
+    Y2() = default;
+    Y2(const int&) = delete;
+    Y2& operator=(const int&) { return *this; }
+};
+
+class B {};
+class D : public B {};
+
+
+template <class T>
+struct AssignableFrom {
+  static int type_constructed;
+  static int type_assigned;
+static int int_constructed;
+  static int int_assigned;
+
+  static void reset() {
+      type_constructed = int_constructed = 0;
+      type_assigned = int_assigned = 0;
+  }
+
+  AssignableFrom() = default;
+
+  explicit AssignableFrom(T) { ++type_constructed; }
+  AssignableFrom& operator=(T) { ++type_assigned; return *this; }
+
+  AssignableFrom(int) { ++int_constructed; }
+  AssignableFrom& operator=(int) { ++int_assigned; return *this; }
+private:
+  AssignableFrom(AssignableFrom const&) = delete;
+  AssignableFrom& operator=(AssignableFrom const&) = delete;
+};
+
+template <class T> int AssignableFrom<T>::type_constructed = 0;
+template <class T> int AssignableFrom<T>::type_assigned = 0;
+template <class T> int AssignableFrom<T>::int_constructed = 0;
+template <class T> int AssignableFrom<T>::int_assigned = 0;
+
+void test_with_test_type() {
+    using T = TestTypes::TestType;
+    T::reset();
+    { // non-empty to empty
+        T::reset_constructors();
+        optional<T> opt;
+        optional<int> other(42);
+        opt = std::move(other);
+        assert(T::alive == 1);
+        assert(T::constructed == 1);
+        assert(T::value_constructed == 1);
+        assert(T::assigned == 0);
+        assert(T::destroyed == 0);
+        assert(static_cast<bool>(other) == true);
+        assert(*other == 42);
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == T(42));
+    }
+    assert(T::alive == 0);
+    { // non-empty to non-empty
+        optional<T> opt(101);
+        optional<int> other(42);
+        T::reset_constructors();
+        opt = std::move(other);
+        assert(T::alive == 1);
+        assert(T::constructed == 0);
+        assert(T::assigned == 1);
+        assert(T::value_assigned == 1);
+        assert(T::destroyed == 0);
+        assert(static_cast<bool>(other) == true);
+        assert(*other == 42);
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == T(42));
+    }
+    assert(T::alive == 0);
+    { // empty to non-empty
+        optional<T> opt(101);
+        optional<int> other;
+        T::reset_constructors();
+        opt = std::move(other);
+        assert(T::alive == 0);
+        assert(T::constructed == 0);
+        assert(T::assigned == 0);
+        assert(T::destroyed == 1);
+        assert(static_cast<bool>(other) == false);
+        assert(static_cast<bool>(opt) == false);
+    }
+    assert(T::alive == 0);
+    { // empty to empty
+        optional<T> opt;
+        optional<int> other;
+        T::reset_constructors();
+        opt = std::move(other);
+        assert(T::alive == 0);
+        assert(T::constructed == 0);
+        assert(T::assigned == 0);
+        assert(T::destroyed == 0);
+        assert(static_cast<bool>(other) == false);
+        assert(static_cast<bool>(opt) == false);
+    }
+    assert(T::alive == 0);
+}
+
+
+void test_ambigious_assign() {
+    using OptInt = std::optional<int>;
+    {
+        using T = AssignableFrom<OptInt&&>;
+        T::reset();
+        {
+            OptInt a(42);
+            std::optional<T> t;
+            t = std::move(a);
+            assert(T::type_constructed == 1);
+            assert(T::type_assigned == 0);
+            assert(T::int_constructed == 0);
+            assert(T::int_assigned == 0);
+        }
+        {
+            using Opt = std::optional<T>;
+            static_assert(!std::is_assignable<Opt&, const OptInt&&>::value, "");
+            static_assert(!std::is_assignable<Opt&, const OptInt&>::value, "");
+            static_assert(!std::is_assignable<Opt&, OptInt&>::value, "");
+        }
+    }
+    {
+        using T = AssignableFrom<OptInt const&&>;
+        T::reset();
+        {
+            const OptInt a(42);
+            std::optional<T> t;
+            t = std::move(a);
+            assert(T::type_constructed == 1);
+            assert(T::type_assigned == 0);
+            assert(T::int_constructed == 0);
+            assert(T::int_assigned == 0);
+        }
+        T::reset();
+        {
+            OptInt a(42);
+            std::optional<T> t;
+            t = std::move(a);
+            assert(T::type_constructed == 1);
+            assert(T::type_assigned == 0);
+            assert(T::int_constructed == 0);
+            assert(T::int_assigned == 0);
+        }
+        {
+            using Opt = std::optional<T>;
+            static_assert(std::is_assignable<Opt&, OptInt&&>::value, "");
+            static_assert(!std::is_assignable<Opt&, const OptInt&>::value, "");
+            static_assert(!std::is_assignable<Opt&, OptInt&>::value, "");
+        }
+    }
+}
+
+
+int main()
+{
+    test_with_test_type();
+    test_ambigious_assign();
+    {
+        optional<int> opt;
+        optional<short> opt2;
+        opt = std::move(opt2);
+        assert(static_cast<bool>(opt2) == false);
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+    }
+    {
+        optional<int> opt;
+        optional<short> opt2(short{2});
+        opt = std::move(opt2);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+        assert(*opt == *opt2);
+    }
+    {
+        optional<int> opt(3);
+        optional<short> opt2;
+        opt = std::move(opt2);
+        assert(static_cast<bool>(opt2) == false);
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+    }
+    {
+        optional<int> opt(3);
+        optional<short> opt2(short{2});
+        opt = std::move(opt2);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+        assert(*opt == *opt2);
+    }
+    {
+        optional<std::unique_ptr<B>> opt;
+        optional<std::unique_ptr<D>> other(new D());
+        opt = std::move(other);
+        assert(static_cast<bool>(opt) == true);
+        assert(static_cast<bool>(other) == true);
+        assert(opt->get() != nullptr);
+        assert(other->get() == nullptr);
+    }
+#ifndef TEST_HAS_NO_EXCEPTIONS
+    {
+        optional<X> opt;
+        optional<int> opt2(42);
+        assert(static_cast<bool>(opt2) == true);
+        try
+        {
+            X::throw_now = true;
+            opt = std::move(opt2);
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 6);
+            assert(static_cast<bool>(opt) == false);
+        }
+    }
+#endif
+}