Implement N4606 optional

Summary:
Adapt implementation of Library Fundamentals TS optional into an implementation of N4606 optional.

  - Update relational operators per http://wg21.link/P0307
  - Update to requirements of http://wg21.link/P0032
  - Extension: Implement trivial copy/move construction/assignment for `optional<T>` when `T` is trivially copyable.

Audit P/Rs for optional LWG issues:
  - 2756 "C++ WP optional<T> should 'forward' T's implicit conversions" Implemented, which also resolves 2753 "Optional's constructors and assignments need constraints" (modulo my refusal to explicitly delete the move operations, which is a design error that I'm working on correcting in the 2756 P/R).
  - 2736 "nullopt_t insufficiently constrained" Already conforming. I've added a test ensuring that `nullopt_t` is not copy-initializable from an empty braced-init-list, which I believe is the root intent of the issue, to avoid regression.
  - 2740 "constexpr optional<T>::operator->" Already conforming.
  - 2746 "Inconsistency between requirements for emplace between optional and variant" No P/R, but note that the author's '"suggested resolution" is already implemented.
  - 2748 "swappable traits for optionals" Already conforming.
  - 2753 "Optional's constructors and assignments need constraints" Implemented.

Most of the work for this patch was done by Casey Carter @ Microsoft. Thank you Casey!



Reviewers: mclow.lists, CaseyCarter, EricWF

Differential Revision: https://reviews.llvm.org/D22741

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@283980 91177308-0d34-0410-b5e6-96231b3b80d8

test/libcxx/utilities/optional/optional.object/optional.object.assign/copy.pass.cpp

@@ -0,0 +1,81 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+// XFAIL: libcpp-no-exceptions
+// <optional>
+
+// optional<T>& operator=(const optional<T>& rhs);
+
+#include <optional>
+#include <string>
+#include <type_traits>
+
+using std::optional;
+
+struct X {};
+
+struct Y
+{
+    Y() = default;
+    Y& operator=(const Y&) { return *this; }
+};
+
+struct Z1
+{
+    Z1() = default;
+    Z1(Z1&&) = default;
+    Z1(const Z1&) = default;
+    Z1& operator=(Z1&&) = default;
+    Z1& operator=(const Z1&) = delete;
+};
+
+struct Z2
+{
+    Z2() = default;
+    Z2(Z2&&) = default;
+    Z2(const Z2&) = delete;
+    Z2& operator=(Z2&&) = default;
+    Z2& operator=(const Z2&) = default;
+};
+
+#if __cplusplus >= 201402
+template <class T>
+constexpr bool
+test()
+{
+    optional<T> opt;
+    optional<T> opt2;
+    opt = opt2;
+    return true;
+}
+#endif
+
+int main()
+{
+    {
+        using T = int;
+        static_assert((std::is_trivially_copy_assignable<optional<T>>::value), "");
+#if __cplusplus >= 201402
+        static_assert(test<T>(), "");
+#endif
+    }
+    {
+        using T = X;
+        static_assert((std::is_trivially_copy_assignable<optional<T>>::value), "");
+#if __cplusplus >= 201402
+        static_assert(test<T>(), "");
+#endif
+    }
+    static_assert(!(std::is_trivially_copy_assignable<optional<Y>>::value), "");
+    static_assert(!(std::is_trivially_copy_assignable<optional<std::string>>::value), "");
+
+    static_assert(!(std::is_copy_assignable<optional<Z1>>::value), "");
+    static_assert(!(std::is_copy_assignable<optional<Z2>>::value), "");
+}

test/libcxx/utilities/optional/optional.object/optional.object.assign/move.pass.cpp

@@ -0,0 +1,78 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+// XFAIL: libcpp-no-exceptions
+// <optional>
+
+// optional<T>& operator=(optional<T>&& rhs);
+
+#include <optional>
+#include <string>
+#include <type_traits>
+#include <utility>
+
+using std::optional;
+
+struct X {};
+
+struct Y
+{
+    Y() = default;
+    Y& operator=(Y&&) { return *this; }
+};
+
+struct Z1
+{
+    Z1() = default;
+    Z1(Z1&&) = default;
+    Z1& operator=(Z1&&) = delete;
+};
+
+struct Z2
+{
+    Z2() = default;
+    Z2(Z2&&) = delete;
+    Z2& operator=(Z2&&) = default;
+};
+
+#if __cplusplus >= 201402
+template <class T>
+constexpr bool
+test()
+{
+    optional<T> opt;
+    optional<T> opt2;
+    opt = std::move(opt2);
+    return true;
+}
+#endif
+
+int main()
+{
+    {
+        using T = int;
+        static_assert((std::is_trivially_copy_constructible<optional<T>>::value), "");
+#if __cplusplus >= 201402
+        static_assert(test<T>(), "");
+#endif
+    }
+    {
+        using T = X;
+        static_assert((std::is_trivially_copy_constructible<optional<T>>::value), "");
+#if __cplusplus >= 201402
+        static_assert(test<T>(), "");
+#endif
+    }
+    static_assert(!(std::is_trivially_move_assignable<optional<Y>>::value), "");
+    static_assert(!(std::is_trivially_move_assignable<optional<std::string>>::value), "");
+
+    static_assert(!(std::is_move_assignable<optional<Z1>>::value), "");
+    static_assert(!(std::is_move_assignable<optional<Z2>>::value), "");
+}

test/libcxx/utilities/optional/optional.object/optional.object.ctor/copy.pass.cpp

@@ -0,0 +1,59 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+// XFAIL: libcpp-no-exceptions
+// <optional>
+
+// optional(const optional<T>& rhs);
+
+#include <optional>
+#include <string>
+#include <type_traits>
+
+using std::optional;
+
+struct X {};
+
+struct Y
+{
+    Y() = default;
+    Y(const Y&) {}
+};
+
+struct Z
+{
+    Z() = default;
+    Z(Z&&) = delete;
+    Z(const Z&) = delete;
+    Z& operator=(Z&&) = delete;
+    Z& operator=(const Z&) = delete;
+};
+
+int main()
+{
+    {
+        using T = int;
+        static_assert((std::is_trivially_copy_constructible<optional<T>>::value), "");
+        constexpr optional<T> opt;
+        constexpr optional<T> opt2 = opt;
+        (void)opt2;
+    }
+    {
+        using T = X;
+        static_assert((std::is_trivially_copy_constructible<optional<T>>::value), "");
+        constexpr optional<T> opt;
+        constexpr optional<T> opt2 = opt;
+        (void)opt2;
+    }
+    static_assert(!(std::is_trivially_copy_constructible<optional<Y>>::value), "");
+    static_assert(!(std::is_trivially_copy_constructible<optional<std::string>>::value), "");
+
+    static_assert(!(std::is_copy_constructible<optional<Z>>::value), "");
+}

test/libcxx/utilities/optional/optional.object/optional.object.ctor/move.pass.cpp

@@ -0,0 +1,60 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+// XFAIL: libcpp-no-exceptions
+// <optional>
+
+// optional(optional<T>&& rhs);
+
+#include <optional>
+#include <string>
+#include <type_traits>
+#include <utility>
+
+using std::optional;
+
+struct X {};
+
+struct Y
+{
+    Y() = default;
+    Y(Y&&) {}
+};
+
+struct Z
+{
+    Z() = default;
+    Z(Z&&) = delete;
+    Z(const Z&) = delete;
+    Z& operator=(Z&&) = delete;
+    Z& operator=(const Z&) = delete;
+};
+
+int main()
+{
+    {
+        using T = int;
+        static_assert((std::is_trivially_copy_constructible<optional<T>>::value), "");
+        constexpr optional<T> opt;
+        constexpr optional<T> opt2 = std::move(opt);
+        (void)opt2;
+    }
+    {
+        using T = X;
+        static_assert((std::is_trivially_copy_constructible<optional<T>>::value), "");
+        constexpr optional<T> opt;
+        constexpr optional<T> opt2 = std::move(opt);
+        (void)opt2;
+    }
+    static_assert(!(std::is_trivially_move_constructible<optional<Y>>::value), "");
+    static_assert(!(std::is_trivially_move_constructible<optional<std::string>>::value), "");
+
+    static_assert(!(std::is_move_constructible<optional<Z>>::value), "");
+}

test/libcxx/utilities/optional/optional.object/special_member_gen.pass.cpp

@@ -0,0 +1,66 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+#include "archetypes.hpp"
+
+template <class T>
+struct SpecialMemberTest {
+    using O = std::optional<T>;
+
+    template <template <class> class TestMF>
+    static constexpr bool check_same() {
+        return TestMF<O>::value == TestMF<T>::value;
+    }
+
+    // Test that optional inherits the correct trivial/non-trivial members
+    static_assert(check_same<std::is_trivially_destructible>(), "");
+    static_assert(check_same<std::is_trivially_copyable>(), "");
+};
+
+template <class ...Args> static void sink(Args&&...) {}
+
+template <class ...TestTypes>
+struct DoTestsMetafunction {
+    DoTestsMetafunction() { sink(SpecialMemberTest<TestTypes>{}...); }
+};
+
+struct TrivialMoveNonTrivialCopy {
+    TrivialMoveNonTrivialCopy() = default;
+    TrivialMoveNonTrivialCopy(const TrivialMoveNonTrivialCopy&) {}
+    TrivialMoveNonTrivialCopy(TrivialMoveNonTrivialCopy&&) = default;
+    TrivialMoveNonTrivialCopy& operator=(const TrivialMoveNonTrivialCopy&) { return *this; }
+    TrivialMoveNonTrivialCopy& operator=(TrivialMoveNonTrivialCopy&&) = default;
+};
+
+struct TrivialCopyNonTrivialMove {
+    TrivialCopyNonTrivialMove() = default;
+    TrivialCopyNonTrivialMove(const TrivialCopyNonTrivialMove&) = default;
+    TrivialCopyNonTrivialMove(TrivialCopyNonTrivialMove&&) {}
+    TrivialCopyNonTrivialMove& operator=(const TrivialCopyNonTrivialMove&) = default;
+    TrivialCopyNonTrivialMove& operator=(TrivialCopyNonTrivialMove&&) { return *this; }
+};
+
+int main()
+{
+    sink(
+        ImplicitTypes::ApplyTypes<DoTestsMetafunction>{},
+        ExplicitTypes::ApplyTypes<DoTestsMetafunction>{},
+        NonLiteralTypes::ApplyTypes<DoTestsMetafunction>{},
+        NonTrivialTypes::ApplyTypes<DoTestsMetafunction>{},
+        DoTestsMetafunction<TrivialMoveNonTrivialCopy, TrivialCopyNonTrivialMove>{}
+    );
+}

test/libcxx/utilities/optional/version.pass.cpp

@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <optional>
+
+#include <optional>
+
+#ifndef _LIBCPP_VERSION
+#error _LIBCPP_VERSION not defined
+#endif
+
+int main()
+{
+}