Implement N4606 optional

[EricWF]

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!

[EricWF]

We should consider adding a storage specialization for trivially copyable types. It's important to do it now because it would be an ABI breaking change later. It would also be possible to provide constexpr optional<T> copy/move operations for such a specialization.

More comments to come.

include/optional

175

I really don't like this constructor. I can see plenty of places where it could get constructed accidentally.
Let's find another way to (A) get rid of the default constructor and (B) privately initialize nullopt_t.

202

Or just __null_state_(0)

259

I've never seen variable template specialization, but I like it :-)

346

It seems like this implementation should support references fine, no? It might be one of those cases that needs std::launder, but __optional_storage looks like it could handle it.

Do you know what the status of optional<T&>is? Is LEWG working on it?

420

There are not constexpr in the spec, and it can't be implemented as a constexpr operation in the vast majority* of cases AFAIK.

[1] http://stackoverflow.com/questions/30632442/c14-constexpr-union-conditional-initialization-in-constructor

[CaseyCarter]

We should consider adding a storage specialization for trivially copyable types. It's important to do it now because it would be an ABI breaking change later. It would also be possible to provide constexpr optional<T> copy/move operations for such a specialization.

Intent of this change was to perform the minimum changes necessary to bring the existing LibFund optional implementation into spec with the WP, so I didn't mess about with the existing design at all, really. That said, I put a bit of effort into providing trivial-and-therefor-constexpr copy/move constructors/assignments for MSVC's optional implementation, so I obviously agree it's a good idea. If you're interested I'd be happy to implement it here as well.

include/optional

175

How about an unspeakable tag argument, e.g.:

struct nullopt_t
{
    struct __secret_tag { explicit __secret_tag() = default; };
    explicit constexpr nullopt_t(__secret_tag, __secret_tag) noexcept {}
};

constexpr nullopt_t nullopt{nullopt_t::__secret_tag{}, nullopt_t::__secret_tag{}};

202

I would have simply value-initialized; I didn't change anything pre-existing that was not necessary to accommodate the spec changes from TS2 to WP optional.

'E' for "empty" would be a good choice as well. It's a shame "Ø" isn't in the basic source character set. ;)

210

There are *four* virtually identical constructors with this same pattern; consider refactoring.

259

I use it *very* extensively in cmcstl2 to workaround performance deficiencies in GCC's concepts implementation, so I've enjoyed riding a roller coaster of bugs for the last year. I can now confidently say that GCC & Clang both have good support for partial specialization of variable templates.

346

It's an explicit requirement in N4606 that optional references are verboten. Yes, that is inconsistent with variant which explicitly *does* support references. I don't know if anyone has been working on it. Hopefully we'll get the differences ironed out sometime before C++20.

Psuedo-destructor syntax isn't valid for reference types, so e.g. __optional_storage's destructor would need a bit of work to support them.

I would want a specialized representation for optional<T&> that stores only a pointer and uses nullptr for the empty state so the general implementation of __optional_storage wouldn't need to support them anyway.

420

These *are* constexpr in Library Fundamentals TS2 (para 44 & 49) just as specified in the resolution of LWG2451. I agree they cannot be implemented as constexpr; I submitted LWG2745 to remove the constexpr and "shall be constexpr if ..." wording.

[CaseyCarter]

Address review comments:

• Defend nullopt_t constructor against Murphy.
• Refactor __optional_storage into three class templates:
  • __optional_destruct_base: conditionally implements non-trivial destruction
  • __optional_copy_base: conditionally implements non-trivial copy/move construction/assignment
  • __optional_storage: presents a clean API to insulate optional from the storage representation. (In theory, specializations of this class can provide novel representations, e.g., optional<T&> could use a T* for its representation with (T*)0 as the empty state.)

[CaseyCarter]

include/optional

315

Where are the tests to validate trivial/constexpr move/copy construct/assign for optional of trivial types?

optional

2 ↗

(On Diff #66142)

It bears repeating. An implementation just can't have too many files named "optional."

Delete this and re-push.

[CaseyCarter]

Remove the extra "optional" file that I somehow managed to add at the top of the directory tree.

[CaseyCarter]

NOTE WELL: This implementation of the "trivially copyable type" optimization critically fails to SFINAE the special member functions. I suggest you put off reviewing until I update the diff again.

include/optional

315

Those tests also validate that the special members don't participate in overload resolution when they're not valid for T, which I haven't implemented here, and is IMO critical for optional to be useful (LWG2753).

[EricWF]

Adding a bunch of inline comments. This looks really great. I should finish the review tommorow.

The biggest problem, which you already noted, is that the special members still lack SFINAE. We need to make sure they are correctly generated. Here's the test case I wrote for it.

include/experimental/optional

11

Let's go with the full _LIBCPP_EXPERIMENTAL_OPTIONAL.

include/optional

143

bad_optional_access should go directly into namespace std, not the versioning namespace, because we don't version exceptions.

158

Just put these includes at the top. If you include <optional> when it's not available then it's your fault. We don't need to optimize for it.

166

Put this right after the first includes.

319

What's up with this default template argument?

405

I don't think we want to check this. Sometime's the implicitly generated destructor is not noexcept.

408

= default;?

411

Don't even declare the destructor.

415

I think we probably want to constrain these or is_constructible<value_type, value_type&&> even though the standard doesn't require it.

783

Urg this is unfortunate. Clang provides a constexpr addressof, but GCC doesn't yet.

Even worse is that this technique doesn't detect explicitly deleted operator& overloads.

802

Calls to declval *need* to be qualified to avoid ADL hijacking.

1167

decay_t is now available :-)

1202

_LIBCPP_STD_VER > 14

test/libcxx/optional/version.pass.cpp

1

test/libcxx/utilities/optional is the correct path for this.

[CaseyCarter]

I should have time to finish up this week.

include/optional

319

I foresee wanting to specialize __optional_storage for types with a built-in invalid state / sentinel value some time, especially if/when the committee decides to allow optional<T&>. This parameter is here *now* so that when that time comes it can be used for selecting specializations without ABI breaking.

405

This was pre-existing in experimental/optional, but I agree. Will remove.

408

This was pre-existing, and it confused me as well, until I recalled [dcl.init]/7: "If a program calls for the default-initialization of an object of a const-qualified type T, T shall be a class type with a user-provided default constructor." I see no reason not to allow e.g. constexpr optional<foo> o;

415

Yes, constraining the constructors and assignments is LWG2753. I'll be sure to implement all the issues that are Tentatively Ready from Chicago.

[CaseyCarter]

Implements the most recent PR for LWG2756 - which also resolves LWG2753 - except that optional<T>'s move operations are not defined as deleted when T is not movable. They instead do not participate in overload resolution. Copyable-but-not-Movable types are an abomination that optional should not propagate. Consequently, optional<T> is both copyable and movable when T is Copyable-but-not-Movable; this is a feature, not a bug ;)

I split Eric's special-member-function triviality/SFINAE test into separate tests:

• An SFINAE test under std, since LWG2753 is Tentatively Ready
• A triviality test under libcxx, since no one has shown an interest in standardizing the triviality of optional<T>'s SMFs.

Implemented a test for LWG2736 "nullopt_t insufficiently constrained." nullopt_t already conformed, but it never hurts to guard against regression.

Wrapped all the everything at 100-ish columns.

[CaseyCarter]

That's everything I'm planning to do for now. Review away.

include/optional

785

I can live with this nearly-pathological corner case being broken without intrinsic addressof.

[CaseyCarter]

Fix triviality impl and tests (you know, because you tend to find errors when you actually *run* the tests)

• Add trivially_assignable tests
• Cleanup:
  • add some missing _LIBCPP_INLINE_VISIBILITY specifiers
  • We're inside _LIBCPP_STD_VER > 14, so use trait_v everywhere instead of trait::value.
  • Use is_trivially_copyable<T> directly, instead of the equivalent but longer is_trivially_copyable<__optional_destruct_base<T>>.
  • "inline constexpr" => "constexpr"

[CaseyCarter]

Nitpicks.

include/optional

168

Why is "Access" capitalized?

648

Again, you've written four nearly identical constructor bodies. This cries out for DRY.

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

37 ↗

(On Diff #67969)

Needs to check triviality of copy/move assignment as well.

[CaseyCarter]

Apply Eric's refactoring to separate the SFINAE constraints from the implementation of the special member functions.

[CaseyCarter]

include/optional

389

Note the intentional difference from Eric's patch: this class deletes the *assignments* as well as the constructions when T is not movable and/or copyable, so that optional<T> is foo_assignable iff T is foo_constructible and foo_copyable.

Given that constructibility partially determines assignment, it may be possible to combine the two sfinae bases cleanly.

[EricWF]

Hi Casey? Sorry about this, but I actually just factored out the __optional_sfinae_ctor_base and __optional_sfinae_assign_base since we'll need them in optional. Could you please apply this patch to yours?

https://gist.github.com/EricWF/49ffb06a2ac904b5f4729c1e72725fbe

include/optional

168

Just make it "bad optional access". I don't think diagnostics should ever be capitalized.

321

I suspect we could make the change is a mostly non-abi breaking change without it, but I'm OK with it in general.
Just add a comment along the lines of "For future specialization."

648

I think we could just lower it to an __optional_storage constructor using

optional(optional<U>&& u) : __base(std::move(u)) {}

or similar

[EricWF]

Additionally I'm perfectly happy to take over this change if you don't want to continue. If you do then thank you very much! I understand it's a lot of work.

[EricWF]

include/optional

752

Please replace this with:

if (!this->has_value())
  __libcpp_throw(bad_optional_access());

764

Same here.

776

Same here.

788

Same here.

[CaseyCarter]

include/optional

389

Given that constructibility partially determines assignment, it may be possible to combine the two sfinae bases cleanly.

This results in 9 specializations of 1 class instead of 4 specializations * 2 classes. I'd call it a wash.

474

I moved these here so there would be one private section, but I'm now thinking it would be cleaner to make __base public and move these __operator_arrow overloads back into a private section at the end of the class body.

[EricWF]

include/optional

389

I actually changed how it was done. Now __optional_sfinae_assign_base_t selects the correct copy/assignment operator definitions based on the copy/move constructor availability. Sorry I missed that in the first patch.

[CaseyCarter]

Hi Casey? Sorry about this, but I actually just factored out the __optional_sfinae_ctor_base and __optional_sfinae_assign_base since we'll need them in optional. Could you please apply this patch to yours?

I could, but then the tests won't run. Could you include the destination of the refactoring in the patch as well?

include/optional

322

Already removed during the sfinae refactor - whoever specializes optional_storage for references will have to specialize it separately for lvalue and rvalue references ;)

649

Already done.

[EricWF]

In D22741#515018, @CaseyCarter wrote:

Hi Casey? Sorry about this, but I actually just factored out the __optional_sfinae_ctor_base and __optional_sfinae_assign_base since we'll need them in optional. Could you please apply this patch to yours?

I could, but then the tests won't run. Could you include the destination of the refactoring in the patch as well?

I already pushed the destination to master. The definitions are at the bottom of __tuple.

[CaseyCarter]

Relocate __operator_arrow; __libcpp_throw; __sfinae_XXX_base relocation.

[EricWF]

The summary says:

Speculatively apply resolution of http://wg21.link/lwg2451 from the TS

It we want to apply the defect report for the WP, not the TS. IE:

2756. C++ WP optional<T> should 'forward' T's implicit conversions

[EricWF]

include/optional

738

These need non-const overloads as well.

[EricWF]

Side note: The current patch make clang ICE a bunch. I've filed a bug against Clang here: https://llvm.org/bugs/show_bug.cgi?id=28978

This bug doesn't seem to affect 3.9 or 3.8 so we shouldn't have a real issue.

[CaseyCarter]

It we want to apply the defect report for the WP, not the TS.

Yes, I implemented 2756 today and did a full audit of all the active optional issues, but forgot to update the Summary.

[CaseyCarter]

__operator_arrow needs to work for *mutable* objects as well as constant objects.

[EricWF]

@CaseyCarter I've updated the implementation for references according to your feedback. optional<T&> and optional<T&&> now have sizeof(void*). What do you think of this patch:

https://gist.github.com/EricWF/a43e98641c3270b411a9358601bc2f0d

[EricWF]

Updating with the final revision.

.gitignore

 
 # PyBuilder
 target/
+
+# Editor by-products
+.vscode/

include/experimental/optional

 //
 //===----------------------------------------------------------------------===//
 
-#ifndef _LIBCPP_OPTIONAL
-#define _LIBCPP_OPTIONAL
+#ifndef _LIBCPP_EXP_OPTIONAL
+#define _LIBCPP_EXP_OPTIONAL
 
 /*
     optional synopsis

 
 #endif  // _LIBCPP_STD_VER > 11
 
-#endif  // _LIBCPP_OPTIONAL
+#endif  // _LIBCPP_EXP_OPTIONAL

include/optional

+// -*- C++ -*-
+//===-------------------------- optional ----------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_OPTIONAL
+#define _LIBCPP_OPTIONAL
+
+/*
+    optional synopsis
+
+// C++1z
+
+namespace std {
+  // 20.6.3, optional for object types
+  template <class T> class optional;
+
+  // 20.6.4, no-value state indicator
+  struct nullopt_t{see below };
+  constexpr nullopt_t nullopt(unspecified );
+
+  // 20.6.5, class bad_optional_access
+  class bad_optional_access;
+
+  // 20.6.6, relational operators
+  template <class T>
+  constexpr bool operator==(const optional<T>&, const optional<T>&);
+  template <class T>
+  constexpr bool operator!=(const optional<T>&, const optional<T>&);
+  template <class T>
+  constexpr bool operator<(const optional<T>&, const optional<T>&);
+  template <class T>
+  constexpr bool operator>(const optional<T>&, const optional<T>&);
+  template <class T>
+  constexpr bool operator<=(const optional<T>&, const optional<T>&);
+  template <class T>
+  constexpr bool operator>=(const optional<T>&, const optional<T>&);
+  template <class T> constexpr bool operator==(const optional<T>&, nullopt_t) noexcept;
+  template <class T> constexpr bool operator==(nullopt_t, const optional<T>&) noexcept;
+  template <class T> constexpr bool operator!=(const optional<T>&, nullopt_t) noexcept;
+  template <class T> constexpr bool operator!=(nullopt_t, const optional<T>&) noexcept;
+  template <class T> constexpr bool operator<(const optional<T>&, nullopt_t) noexcept;
+  template <class T> constexpr bool operator<(nullopt_t, const optional<T>&) noexcept;
+  template <class T> constexpr bool operator<=(const optional<T>&, nullopt_t) noexcept;
+  template <class T> constexpr bool operator<=(nullopt_t, const optional<T>&) noexcept;
+  template <class T> constexpr bool operator>(const optional<T>&, nullopt_t) noexcept;
+  template <class T> constexpr bool operator>(nullopt_t, const optional<T>&) noexcept;
+  template <class T> constexpr bool operator>=(const optional<T>&, nullopt_t) noexcept;
+  template <class T> constexpr bool operator>=(nullopt_t, const optional<T>&) noexcept;
+
+  // 20.6.8, comparison with T
+  template <class T> constexpr bool operator==(const optional<T>&, const T&);
+  template <class T> constexpr bool operator==(const T&, const optional<T>&);
+  template <class T> constexpr bool operator!=(const optional<T>&, const T&);
+  template <class T> constexpr bool operator!=(const T&, const optional<T>&);
+  template <class T> constexpr bool operator<(const optional<T>&, const T&);
+  template <class T> constexpr bool operator<(const T&, const optional<T>&);
+  template <class T> constexpr bool operator<=(const optional<T>&, const T&);
+  template <class T> constexpr bool operator<=(const T&, const optional<T>&);
+  template <class T> constexpr bool operator>(const optional<T>&, const T&);
+  template <class T> constexpr bool operator>(const T&, const optional<T>&);
+  template <class T> constexpr bool operator>=(const optional<T>&, const T&);
+  template <class T> constexpr bool operator>=(const T&, const optional<T>&);
+
+  // 20.6.9, specialized algorithms
+  template <class T> void swap(optional<T>&, optional<T>&) noexcept(see below );
+  template <class T> constexpr optional<see below > make_optional(T&&);
+  template <class T, class... Args>
+    constexpr optional<T> make_optional(Args&&... args);
+  template <class T, class U, class... Args>
+    constexpr optional<T> make_optional(initializer_list<U> il, Args&&... args);
+
+  // 20.6.10, hash support
+  template <class T> struct hash;
+  template <class T> struct hash<optional<T>>;
+
+  template <class T> class optional {
+  public:
+    using value_type = T;
+
+    // 20.6.3.1, constructors
+    constexpr optional() noexcept;
+    constexpr optional(nullopt_t) noexcept;
+    optional(const optional &);
+    optional(optional &&) noexcept(see below );
+    constexpr optional(const T &);
+    constexpr optional(T &&);
+    template <class... Args> constexpr explicit optional(in_place_t, Args &&...);
+    template <class U, class... Args>
+      constexpr explicit optional(in_place_t, initializer_list<U>, Args &&...);
+
+    // 20.6.3.2, destructor
+    ~optional();
+
+    // 20.6.3.3, assignment
+    optional &operator=(nullopt_t) noexcept;
+    optional &operator=(const optional &);
+    optional &operator=(optional &&) noexcept(see below );
+    template <class U> optional &operator=(U &&);
+    template <class... Args> void emplace(Args &&...);
+    template <class U, class... Args>
+      void emplace(initializer_list<U>, Args &&...);
+
+    // 20.6.3.4, swap
+    void swap(optional &) noexcept(see below );
+
+    // 20.6.3.5, observers
+    constexpr T const *operator->() const;
+    constexpr T *operator->();
+    constexpr T const &operator*() const &;
+    constexpr T &operator*() &;
+    constexpr T &&operator*() &&;
+    constexpr const T &&operator*() const &&;
+    constexpr explicit operator bool() const noexcept;
+    constexpr bool has_value() const noexcept;
+    constexpr T const &value() const &;
+    constexpr T &value() &;
+    constexpr T &&value() &&;
+    constexpr const T &&value() const &&;
+    template <class U> constexpr T value_or(U &&) const &;
+    template <class U> constexpr T value_or(U &&) &&;
+
+    // 20.6.3.6, modifiers
+    void reset() noexcept;
+
+  private:
+    T *val; // exposition only
+  };
+} // namespace std
+
+*/
+
+#include <__config>
+#include <functional>
+#include <stdexcept>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+class _LIBCPP_EXCEPTION_ABI bad_optional_access
+    : public std::logic_error
+{
+public:
+    bad_optional_access() : std::logic_error("Bad optional Access") {}
+
+    // Get the key function ~bad_optional_access() into the dylib
+    virtual ~bad_optional_access() _NOEXCEPT;
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+
+#if _LIBCPP_STD_VER > 14
+
+#include <initializer_list>
+#include <type_traits>
+#include <utility>
+#include <new>
+#include <__functional_base>
+#include <__undef_min_max>
+#include <__debug>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+struct nullopt_t
+{
+    struct __secret_tag { explicit __secret_tag() = default; };
+    explicit constexpr nullopt_t(__secret_tag, __secret_tag) noexcept {}
+};
+
+constexpr nullopt_t nullopt{nullopt_t::__secret_tag{}, nullopt_t::__secret_tag{}};
+
+template <class _Tp, bool = is_trivially_destructible<_Tp>::value>
+struct __optional_destruct_base
+{
+    typedef _Tp value_type;
+    union
+    {
+        char __null_state_;
+        value_type __val_;
+    };
+    bool __engaged_;
+
+    _LIBCPP_INLINE_VISIBILITY
+    ~__optional_destruct_base()
+    {
+        if (__engaged_)
+            __val_.~value_type();
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr __optional_destruct_base() noexcept
+        :  __null_state_(),
+           __engaged_(false) {}
+
+    template <class... _Args>
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr
+    explicit __optional_destruct_base(in_place_t, _Args&&... __args)
+        :  __val_(_VSTD::forward<_Args>(__args)...),
+           __engaged_(true) {}
+};
+
+template <class _Tp>
+struct __optional_destruct_base<_Tp, true>
+{
+    typedef _Tp value_type;
+    union
+    {
+        char __null_state_;
+        value_type __val_;
+    };
+    bool __engaged_;
+
+    _LIBCPP_INLINE_VISIBILITY
+    ~__optional_destruct_base() = default;
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr __optional_destruct_base() noexcept
+        :  __null_state_(),
+           __engaged_(false) {}
+
+    template <class... _Args>
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr
+    explicit __optional_destruct_base(in_place_t, _Args&&... __args)
+        :  __val_(_VSTD::forward<_Args>(__args)...),
+           __engaged_(true) {}
+};
+
+template <class _Tp, bool = is_trivially_copyable<_Tp>::value>
+struct __optional_copy_base : __optional_destruct_base<_Tp>
+{
+    using __base = __optional_destruct_base<_Tp>;
+    using typename __base::value_type;
+
+    using __base::__base;
+
+    _LIBCPP_INLINE_VISIBILITY
+    __optional_copy_base() = default;
+
+    _LIBCPP_INLINE_VISIBILITY
+    __optional_copy_base(const __optional_copy_base& __x)
+    {
+        if (__x.__engaged_)
+        {
+            ::new(_VSTD::addressof(this->__val_)) value_type(__x.__val_);
+            this->__engaged_ = true;
+        }
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    __optional_copy_base(__optional_copy_base&& __x)
+        noexcept(is_nothrow_move_constructible<_Tp>::value)
+    {
+        if (__x.__engaged_)
+        {
+            ::new(_VSTD::addressof(this->__val_)) value_type(_VSTD::move(__x.__val_));
+            this->__engaged_ = true;
+        }
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    __optional_copy_base&
+    operator=(const __optional_copy_base& __opt)
+    {
+        if (this->__engaged_ == __opt.__engaged_)
+        {
+            if (this->__engaged_)
+                this->__val_ = __opt.__val_;
+        }
+        else
+        {
+            if (this->__engaged_)
+                this->__val_.~value_type();
+            else
+                ::new(_VSTD::addressof(this->__val_)) value_type(__opt.__val_);
+            this->__engaged_ = __opt.__engaged_;
+        }
+        return *this;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    __optional_copy_base&
+    operator=(__optional_copy_base&& __opt)
+        noexcept(is_nothrow_move_assignable<value_type>::value &&
+                 is_nothrow_move_constructible<value_type>::value)
+    {
+        if (this->__engaged_ == __opt.__engaged_)
+        {
+            if (this->__engaged_)
+                this->__val_ = _VSTD::move(__opt.__val_);
+        }
+        else
+        {
+            if (this->__engaged_)
+                this->__val_.~value_type();
+            else
+                ::new(_VSTD::addressof(this->__val_)) value_type(_VSTD::move(__opt.__val_));
+            this->__engaged_ = __opt.__engaged_;
+        }
+        return *this;
+    }
+};
+
+template <class _Tp>
+struct __optional_copy_base<_Tp, true> : __optional_destruct_base<_Tp>
+{
+    using __optional_destruct_base<_Tp>::__optional_destruct_base;
+};
+
+template <class _Tp, class = void>
+class __optional_storage : __optional_copy_base<_Tp>
+{
+public:
+    using __base = __optional_copy_base<_Tp>;
+    using typename __base::value_type;
+
+    using __base::__base;
+
+    __optional_storage() = default;
+
+    // LWG2451: conversion from optional<_Up>&&
+    template <class _Up, enable_if_t<!is_same<_Tp, _Up>::value, int> = 0>
+    _LIBCPP_INLINE_VISIBILITY
+    __optional_storage(__optional_storage<_Up>&& __x)
+    {
+        if (__x.has_value())
+            __construct(_VSTD::move(__x.__get()));
+    }
+
+    // LWG2451: conversion from const optional<_Up>&
+    template <class _Up, enable_if_t<!is_same<_Tp, _Up>::value, int> = 0>
+    _LIBCPP_INLINE_VISIBILITY
+    __optional_storage(const __optional_storage<_Up>& __x)
+    {
+        if (__x.has_value())
+            __construct(__x.__get());
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr bool has_value() const noexcept
+    {
+        return this->__engaged_;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr value_type& __get() noexcept
+    {
+        return this->__val_;
+    }
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr const value_type& __get() const noexcept
+    {
+        return this->__val_;
+    }
+
+    template <class... _Args>
+    _LIBCPP_INLINE_VISIBILITY
+    void __construct(_Args&&... __args)
+    {
+        _LIBCPP_ASSERT(!has_value(), "__construct called for engaged __optional_storage");
+        ::new(_VSTD::addressof(this->__val_)) value_type(_VSTD::forward<_Args>(__args)...);
+        this->__engaged_ = true;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    void reset() noexcept
+    {
+        if (this->__engaged_)
+        {
+            this->__val_.~value_type();
+            this->__engaged_ = false;
+        }
+    }
+};
+
+template <class _Tp, template <class...> class _Template>
+constexpr bool _Is_specialization = false;
+template <class... _Args, template <class...> class _Template>
+constexpr bool _Is_specialization<_Template<_Args...>, _Template> = true;
+
+template <class _Tp>
+class optional
+    : private __optional_storage<_Tp>
+{
+    template <class> friend class optional;
+    using __base = __optional_storage<_Tp>;
+public:
+    using value_type = _Tp;
+
+    static_assert(!is_reference<value_type>::value,
+        "Instantiation of optional with a reference type is ill-formed.");
+    static_assert(!is_same<typename remove_cv<value_type>::type, nullopt_t>::value,
+        "Instantiation of optional with a nullopt_t type is ill-formed.");
+    static_assert(is_reference<value_type>::value || is_object<value_type>::value,
+        "Instantiation of optional with a non-object type is undefined behavior.");
+    static_assert(is_nothrow_destructible<value_type>::value,
+        "Instantiation of optional with an object type that is not noexcept destructible is undefined behavior.");
+
+    _LIBCPP_INLINE_VISIBILITY constexpr optional() noexcept {}
+    _LIBCPP_INLINE_VISIBILITY optional(const optional&) = default;
+    _LIBCPP_INLINE_VISIBILITY optional(optional&&) = default;
+    _LIBCPP_INLINE_VISIBILITY ~optional() = default;
+    _LIBCPP_INLINE_VISIBILITY constexpr optional(nullopt_t) noexcept {}
+    _LIBCPP_INLINE_VISIBILITY constexpr optional(const value_type& __v)
+        : __base(in_place, __v) {}
+    _LIBCPP_INLINE_VISIBILITY constexpr optional(value_type&& __v)
+        : __base(in_place, _VSTD::move(__v)) {}
+
+    // LWG2451: conditionally explicit conversion from _Up
+    template <class _Up>
+        using _AllowDirectConversion = typename conjunction<
+            negation<is_same<decay_t<_Up>, _Tp>>,
+            is_constructible<_Tp, _Up>>::type;
+    template <class _Up, enable_if_t<conjunction<
+        _AllowDirectConversion<_Up>,
+        is_convertible<_Up, _Tp>>::value, int> = 0>
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr optional(_Up&& __v)
+        : __base(in_place, _VSTD::forward<_Up>(__v)) {}
+    template <class _Up, enable_if_t<conjunction<
+        _AllowDirectConversion<_Up>,
+        negation<is_convertible<_Up, _Tp>>>::value, int> = 0>
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr explicit optional(_Up&& __v)
+        : __base(in_place, _VSTD::forward<_Up>(__v)) {}
+
+    // LWG2451 specifies the following four conversions are to be constexpr if
+    // the selected constructor for the contained value is constexpr;  that
+    // requirement is not implementable. (Hence the annotation:
+    // "/* constexpr? */".)
+
+    // LWG2451: conditionally explicit conversion from const optional<_Up>&
+    template <class _Up>
+        using _AllowConstConversion = typename conjunction<
+            negation<is_same<decay_t<_Up>, _Tp>>,
+            is_constructible<_Tp, const _Up&>,
+            negation<is_constructible<_Tp, const optional<_Up>&>>,
+            negation<is_convertible<const optional<_Up>&, _Tp>>>::type;
+    template <class _Up, enable_if_t<conjunction<
+        _AllowConstConversion<_Up>,
+        is_convertible<const _Up&, _Tp>>::value, int> = 0>
+    _LIBCPP_INLINE_VISIBILITY
+    /* constexpr? */ optional(const optional<_Up>& __v)
+        : __base(static_cast<const __optional_storage<_Up>&>(__v)) {}
+    template <class _Up, enable_if_t<conjunction<
+        _AllowConstConversion<_Up>,
+        negation<is_convertible<const _Up&, _Tp>>>::value, int> = 0>
+    _LIBCPP_INLINE_VISIBILITY
+    /* constexpr? */ explicit optional(const optional<_Up>& __v)
+        : __base(static_cast<const __optional_storage<_Up>&>(__v)) {}
+
+    // LWG2451: conditionally explicit conversion from optional<_Up>&&
+    template <class _Up>
+        using _AllowRvalueConversion = typename conjunction<
+            negation<is_same<decay_t<_Up>, _Tp>>,
+            is_constructible<_Tp, _Up>,
+            negation<is_constructible<_Tp, optional<_Up>>>,
+            negation<is_convertible<optional<_Up>, _Tp>>>::type;
+    template <class _Up, enable_if_t<conjunction<
+        _AllowRvalueConversion<_Up>,
+        is_convertible<_Up, _Tp>>::value, int> = 0>
+    _LIBCPP_INLINE_VISIBILITY
+    /* constexpr? */ optional(optional<_Up>&& __v)
+        : __base(static_cast<__optional_storage<_Up>&&>(__v)) {}
+    template <class _Up, enable_if_t<conjunction<
+        _AllowRvalueConversion<_Up>,
+        negation<is_convertible<_Up, _Tp>>>::value, int> = 0>
+    _LIBCPP_INLINE_VISIBILITY
+    /* constexpr? */ explicit optional(optional<_Up>&& __v)
+        : __base(static_cast<__optional_storage<_Up>&&>(__v)) {}
+
+    template <class... _Args,
+              class = typename enable_if
+                      <
+                           is_constructible<value_type, _Args...>::value
+                      >::type
+             >
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr
+    explicit optional(in_place_t, _Args&&... __args)
+        : __base(in_place, _VSTD::forward<_Args>(__args)...) {}
+
+    template <class _Up, class... _Args,
+              class = typename enable_if
+                      <
+                           is_constructible<value_type, initializer_list<_Up>&, _Args...>::value
+                      >::type
+             >
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr
+    explicit optional(in_place_t, initializer_list<_Up> __il, _Args&&... __args)
+        : __base(in_place, __il, _VSTD::forward<_Args>(__args)...) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    optional& operator=(nullopt_t) noexcept
+    {
+        reset();
+        return *this;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY optional& operator=(const optional&) = default;
+    _LIBCPP_INLINE_VISIBILITY optional& operator=(optional&&) = default;
+
+    // NB: LWG2451 changes the constraints of this signature.
+    template <class _Up,
+              class = typename enable_if
+                      <
+                          !is_same<decay_t<_Up>, nullopt_t>::value &&
+                          !_Is_specialization<_Up, optional> &&
+                          is_constructible<value_type, _Up>::value &&
+                          is_assignable<value_type&, _Up>::value
+                      >::type
+             >
+    _LIBCPP_INLINE_VISIBILITY
+    optional&
+    operator=(_Up&& __v)
+    {
+        if (this->has_value())
+            this->__get() = _VSTD::forward<_Up>(__v);
+        else
+            this->__construct(_VSTD::forward<_Up>(__v));
+        return *this;
+    }
+
+    // LWG2451: converting assignment from const optional<U>&
+    template <class _Up,
+              class = typename enable_if
+                      <
+                          !is_same<decay_t<_Up>, value_type>::value &&
+                          is_constructible<value_type, const _Up&>::value &&
+                          is_assignable<value_type&, const _Up&>::value
+                      >::type
+             >
+    _LIBCPP_INLINE_VISIBILITY
+    optional&
+    operator=(const optional<_Up>& __v)
+    {
+        if (this->has_value())
+        {
+            if (__v.has_value())
+                this->__get() = __v.__get();
+            else
+                reset();
+        }
+        else if (__v.has_value())
+            this->__construct(__v.__get());
+        return *this;
+    }
+
+    // LWG2451: converting assignment from optional<U>&&
+    template <class _Up,
+              class = typename enable_if
+                      <
+                          !is_same<decay_t<_Up>, value_type>::value &&
+                          is_constructible<value_type, _Up>::value &&
+                          is_assignable<value_type&, _Up>::value
+                      >::type
+             >
+    _LIBCPP_INLINE_VISIBILITY
+    optional&
+    operator=(optional<_Up>&& __v)
+    {
+        if (this->has_value())
+        {
+            if (__v.has_value())
+                this->__get() = _VSTD::move(__v.__get());
+            else
+                reset();
+        }
+        else if (__v.has_value())
+            this->__construct(_VSTD::move(__v.__get()));
+        return *this;
+    }
+
+    template <class... _Args,
+              class = typename enable_if
+                      <
+                          is_constructible<value_type, _Args...>::value
+                      >::type
+             >
+    _LIBCPP_INLINE_VISIBILITY
+    void
+    emplace(_Args&&... __args)
+    {
+        reset();
+        this->__construct(_VSTD::forward<_Args>(__args)...);
+    }
+
+    template <class _Up, class... _Args,
+              class = typename enable_if
+                      <
+                          is_constructible<value_type, initializer_list<_Up>&, _Args...>::value
+                      >::type
+             >
+    _LIBCPP_INLINE_VISIBILITY
+    void
+    emplace(initializer_list<_Up> __il, _Args&&... __args)
+    {
+        reset();
+        this->__construct(__il, _VSTD::forward<_Args>(__args)...);
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    void
+    swap(optional& __opt)
+        noexcept(is_nothrow_move_constructible<value_type>::value &&
+                 __is_nothrow_swappable<value_type>::value)
+    {
+        if (this->has_value() == __opt.has_value())
+        {
+            using _VSTD::swap;
+            if (this->has_value())
+                swap(this->__get(), __opt.__get());
+        }
+        else
+        {
+            if (this->has_value())
+            {
+                __opt.__construct(_VSTD::move(this->__get()));
+                reset();
+            }
+            else
+            {
+                this->__construct(_VSTD::move(__opt.__get()));
+                __opt.reset();
+            }
+        }
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr
+    value_type const*
+    operator->() const
+    {
+        _LIBCPP_ASSERT(this->has_value(), "optional operator-> called for disengaged value");
+#if __has_builtin(__builtin_addressof)
+        return _VSTD::addressof(this->__get());
+#else
+        return __operator_arrow(__has_operator_addressof<value_type>{});
+#endif
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr
+    value_type*
+    operator->()
+    {
+        _LIBCPP_ASSERT(this->has_value(), "optional operator-> called for disengaged value");
+#if __has_builtin(__builtin_addressof)
+        return _VSTD::addressof(this->__get());
+#else
+        return __operator_arrow(__has_operator_addressof<value_type>{});
+#endif
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr
+    const value_type&
+    operator*() const&
+    {
+        _LIBCPP_ASSERT(this->has_value(), "optional operator* called for disengaged value");
+        return this->__get();
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr
+    value_type&
+    operator*() &
+    {
+        _LIBCPP_ASSERT(this->has_value(), "optional operator* called for disengaged value");
+        return this->__get();
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr
+    value_type&&
+    operator*() &&
+    {
+        _LIBCPP_ASSERT(this->has_value(), "optional operator* called for disengaged value");
+        return _VSTD::move(this->__get());
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr
+    const value_type&&
+    operator*() const&&
+    {
+        _LIBCPP_ASSERT(this->has_value(), "optional operator* called for disengaged value");
+        return _VSTD::move(this->__get());
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr explicit operator bool() const noexcept { return has_value(); }
+
+    using __base::has_value;
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr value_type const& value() const&
+    {
+        if (!this->has_value())
+#ifndef _LIBCPP_NO_EXCEPTIONS
+            throw bad_optional_access();
+#else
+            assert(!"bad optional access");
+#endif
+        return this->__get();
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr value_type& value() &
+    {
+        if (!this->has_value())
+#ifndef _LIBCPP_NO_EXCEPTIONS
+            throw bad_optional_access();
+#else
+            assert(!"bad optional access");
+#endif
+        return this->__get();
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr value_type&& value() &&
+    {
+        if (!this->has_value())
+#ifndef _LIBCPP_NO_EXCEPTIONS
+            throw bad_optional_access();
+#else
+            assert(!"bad optional access");
+#endif
+        return _VSTD::move(this->__get());
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr value_type const&& value() const&&
+    {
+        if (!this->has_value())
+#ifndef _LIBCPP_NO_EXCEPTIONS
+            throw bad_optional_access();
+#else
+            assert(!"bad optional access");
+#endif
+        return _VSTD::move(this->__get());
+    }
+
+    template <class _Up>
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr value_type value_or(_Up&& __v) const&
+    {
+        static_assert(is_copy_constructible<value_type>::value,
+                      "optional<T>::value_or: T must be copy constructible");
+        static_assert(is_convertible<_Up, value_type>::value,
+                      "optional<T>::value_or: U must be convertible to T");
+        return this->has_value() ? this->__get() :
+                                  static_cast<value_type>(_VSTD::forward<_Up>(__v));
+    }
+
+    template <class _Up>
+    _LIBCPP_INLINE_VISIBILITY
+    value_type value_or(_Up&& __v) &&
+    {
+        static_assert(is_move_constructible<value_type>::value,
+                      "optional<T>::value_or: T must be move constructible");
+        static_assert(is_convertible<_Up, value_type>::value,
+                      "optional<T>::value_or: U must be convertible to T");
+        return this->has_value() ? _VSTD::move(this->__get()) :
+                                  static_cast<value_type>(_VSTD::forward<_Up>(__v));
+    }
+
+    using __base::reset;
+
+private:
+    _LIBCPP_INLINE_VISIBILITY
+    value_type const*
+    __operator_arrow(true_type) const
+    {
+        return _VSTD::addressof(this->__get());
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr
+    value_type const*
+    __operator_arrow(false_type) const
+    {
+        return &this->__get();
+    }
+};
+
+// Comparisons between optionals
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() == declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator==(const optional<_Tp>& __x, const optional<_Tp>& __y)
+{
+    if (static_cast<bool>(__x) != static_cast<bool>(__y))
+        return false;
+    if (!static_cast<bool>(__x))
+        return true;
+    return *__x == *__y;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() != declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator!=(const optional<_Tp>& __x, const optional<_Tp>& __y)
+{
+    if (static_cast<bool>(__x) != static_cast<bool>(__y))
+        return true;
+    if (!static_cast<bool>(__x))
+        return false;
+    return *__x != *__y;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() < declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator<(const optional<_Tp>& __x, const optional<_Tp>& __y)
+{
+    if (!static_cast<bool>(__y))
+        return false;
+    if (!static_cast<bool>(__x))
+        return true;
+    return *__x < *__y;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() > declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator>(const optional<_Tp>& __x, const optional<_Tp>& __y)
+{
+    if (!static_cast<bool>(__x))
+        return false;
+    if (!static_cast<bool>(__y))
+        return true;
+    return *__x > *__y;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() <= declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator<=(const optional<_Tp>& __x, const optional<_Tp>& __y)
+{
+    if (!static_cast<bool>(__x))
+        return true;
+    if (!static_cast<bool>(__y))
+        return false;
+    return *__x <= *__y;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() >= declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator>=(const optional<_Tp>& __x, const optional<_Tp>& __y)
+{
+    if (!static_cast<bool>(__y))
+        return true;
+    if (!static_cast<bool>(__x))
+        return false;
+    return *__x >= *__y;
+}
+
+
+// Comparisons with nullopt
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator==(const optional<_Tp>& __x, nullopt_t) noexcept
+{
+    return !static_cast<bool>(__x);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator==(nullopt_t, const optional<_Tp>& __x) noexcept
+{
+    return !static_cast<bool>(__x);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator!=(const optional<_Tp>& __x, nullopt_t) noexcept
+{
+    return static_cast<bool>(__x);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator!=(nullopt_t, const optional<_Tp>& __x) noexcept
+{
+    return static_cast<bool>(__x);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator<(const optional<_Tp>&, nullopt_t) noexcept
+{
+    return false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator<(nullopt_t, const optional<_Tp>& __x) noexcept
+{
+    return static_cast<bool>(__x);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator<=(const optional<_Tp>& __x, nullopt_t) noexcept
+{
+    return !static_cast<bool>(__x);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator<=(nullopt_t, const optional<_Tp>& __x) noexcept
+{
+    return true;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator>(const optional<_Tp>& __x, nullopt_t) noexcept
+{
+    return static_cast<bool>(__x);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator>(nullopt_t, const optional<_Tp>& __x) noexcept
+{
+    return false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator>=(const optional<_Tp>&, nullopt_t) noexcept
+{
+    return true;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator>=(nullopt_t, const optional<_Tp>& __x) noexcept
+{
+    return !static_cast<bool>(__x);
+}
+
+// Comparisons with T
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() == declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator==(const optional<_Tp>& __x, const _Tp& __v)
+{
+    return static_cast<bool>(__x) ? *__x == __v : false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() == declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator==(const _Tp& __v, const optional<_Tp>& __x)
+{
+    return static_cast<bool>(__x) ? __v == *__x : false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() != declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator!=(const optional<_Tp>& __x, const _Tp& __v)
+{
+    return static_cast<bool>(__x) ? *__x != __v : true;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() != declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator!=(const _Tp& __v, const optional<_Tp>& __x)
+{
+    return static_cast<bool>(__x) ? __v != *__x : true;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() < declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator<(const optional<_Tp>& __x, const _Tp& __v)
+{
+    return static_cast<bool>(__x) ? *__x < __v : true;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() < declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator<(const _Tp& __v, const optional<_Tp>& __x)
+{
+    return static_cast<bool>(__x) ? __v < *__x : false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() <= declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator<=(const optional<_Tp>& __x, const _Tp& __v)
+{
+    return static_cast<bool>(__x) ? *__x <= __v : true;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() <= declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator<=(const _Tp& __v, const optional<_Tp>& __x)
+{
+    return static_cast<bool>(__x) ? __v <= *__x : false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() > declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator>(const optional<_Tp>& __x, const _Tp& __v)
+{
+    return static_cast<bool>(__x) ? *__x > __v : false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() > declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator>(const _Tp& __v, const optional<_Tp>& __x)
+{
+    return static_cast<bool>(__x) ? __v > *__x : true;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() >= declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator>=(const optional<_Tp>& __x, const _Tp& __v)
+{
+    return static_cast<bool>(__x) ? *__x >= __v : false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+typename enable_if<
+    is_convertible<decltype(declval<const _Tp&>() >= declval<const _Tp&>()), bool>::value,
+    bool
+>::type
+operator>=(const _Tp& __v, const optional<_Tp>& __x)
+{
+    return static_cast<bool>(__x) ? __v >= *__x : true;
+}
+
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if<
+    is_move_constructible<_Tp>::value && __is_swappable<_Tp>::value,
+    void
+>::type
+swap(optional<_Tp>& __x, optional<_Tp>& __y) noexcept(noexcept(__x.swap(__y)))
+{
+    __x.swap(__y);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+optional<typename decay<_Tp>::type>
+make_optional(_Tp&& __v)
+{
+    return optional<typename decay<_Tp>::type>(_VSTD::forward<_Tp>(__v));
+}
+
+template <class _Tp, class... _Args>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr optional<_Tp>
+make_optional(_Args&&... __args)
+{
+    return optional<_Tp>(in_place, _VSTD::forward<_Args>(__args)...);
+}
+
+template <class _Tp, class _Up, class... _Args>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr optional<_Tp>
+make_optional(initializer_list<_Up> __il,  _Args&&... __args)
+{
+    return optional<_Tp>(in_place, __il, _VSTD::forward<_Args>(__args)...);
+}
+
+
+template <class _Tp>
+struct _LIBCPP_TYPE_VIS_ONLY hash<optional<_Tp> >
+{
+    typedef optional<_Tp> argument_type;
+    typedef size_t        result_type;
+
+    _LIBCPP_INLINE_VISIBILITY
+    result_type operator()(const argument_type& __opt) const _NOEXCEPT
+    {
+        return static_cast<bool>(__opt) ? hash<_Tp>()(*__opt) : 0;
+    }
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif  // _LIBCPP_STD_VER > 17
+
+#endif  // _LIBCPP_OPTIONAL

src/optional.cpp

 //
 //===----------------------------------------------------------------------===//
 
+#include "optional"
 #include "experimental/optional"
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifdef _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
+
+bad_optional_access::~bad_optional_access() _NOEXCEPT {}
+
+#else
+
+bad_optional_access::~bad_optional_access() _NOEXCEPT = default;
+
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
 _LIBCPP_BEGIN_NAMESPACE_EXPERIMENTAL
 
 #ifdef _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS

test/libcxx/optional/version.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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()
+{
+}

test/std/utilities/meta/meta.unary/meta.unary.prop/is_nothrow_swappable_with.pass.cpp

                       !std::is_nothrow_swappable_with<A&, A&>::value, "");
     }
     {
-        // test that hetrogenius swap is allowed only if both 'swap(A, B)' and
+        // test that heterogeneous swap is allowed only if both 'swap(A, B)' and
         // 'swap(B, A)' are valid.
         static_assert(std::is_nothrow_swappable_with<A&, B&>::value, "");
         static_assert(!std::is_nothrow_swappable_with<A&, C&>::value &&

test/std/utilities/optional/optional.hash/hash.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> struct hash<optional<T>>;
+
+#include <optional>
+#include <string>
+#include <memory>
+#include <cassert>
+
+
+int main()
+{
+    using std::optional;
+    const std::size_t nullopt_hash =
+        std::hash<optional<double>>{}(optional<double>{});
+
+    {
+        typedef int T;
+        optional<T> opt;
+        assert(std::hash<optional<T>>{}(opt) == nullopt_hash);
+        opt = 2;
+        assert(std::hash<optional<T>>{}(opt) == std::hash<T>{}(*opt));
+    }
+    {
+        typedef std::string T;
+        optional<T> opt;
+        assert(std::hash<optional<T>>{}(opt) == nullopt_hash);
+        opt = std::string("123");
+        assert(std::hash<optional<T>>{}(opt) == std::hash<T>{}(*opt));
+    }
+    {
+        typedef std::unique_ptr<int> T;
+        optional<T> opt;
+        assert(std::hash<optional<T>>{}(opt) == nullopt_hash);
+        opt = std::unique_ptr<int>(new int(3));
+        assert(std::hash<optional<T>>{}(opt) == std::hash<T>{}(*opt));
+    }
+}

test/std/utilities/optional/optional.bad_optional_access/default.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// class bad_optional_access is default constructible
+
+#include <optional>
+#include <type_traits>
+
+int main()
+{
+    using std::bad_optional_access;
+    bad_optional_access ex;
+}

test/std/utilities/optional/optional.bad_optional_access/derive.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// class bad_optional_access : public logic_error
+
+#include <optional>
+#include <type_traits>
+
+int main()
+{
+    using std::bad_optional_access;
+
+    static_assert(std::is_base_of<std::logic_error, bad_optional_access>::value, "");
+    static_assert(std::is_convertible<bad_optional_access*, std::logic_error*>::value, "");
+}

test/std/utilities/optional/optional.comp_with_t/equal.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator==(const optional<T>& x, const T& v);
+// template <class T> constexpr bool operator==(const T& v, const optional<T>& x);
+
+#include <optional>
+
+using std::optional;
+
+struct X
+{
+    int i_;
+
+    constexpr X(int i) : i_(i) {}
+};
+
+constexpr bool operator == ( const X &lhs, const X &rhs )
+    { return lhs.i_ == rhs.i_ ; }
+
+int main()
+{
+    {
+    typedef X T;
+    typedef optional<T> O;
+
+    constexpr T val(2);
+    constexpr O o1;       // disengaged
+    constexpr O o2{1};    // engaged
+    constexpr O o3{val};  // engaged
+
+    static_assert ( !(o1 == T(1)), "" );
+    static_assert (  (o2 == T(1)), "" );
+    static_assert ( !(o3 == T(1)), "" );
+    static_assert (  (o3 == T(2)), "" );
+    static_assert (  (o3 == val),  "" );
+
+    static_assert ( !(T(1) == o1), "" );
+    static_assert (  (T(1) == o2), "" );
+    static_assert ( !(T(1) == o3), "" );
+    static_assert (  (T(2) == o3), "" );
+    static_assert (  (val  == o3), "" );
+    }
+}

test/std/utilities/optional/optional.comp_with_t/greater.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator>(const optional<T>& x, const T& v);
+// template <class T> constexpr bool operator>(const T& v, const optional<T>& x);
+
+#include <optional>
+
+using std::optional;
+
+struct X
+{
+    int i_;
+
+    constexpr X(int i) : i_(i) {}
+};
+
+constexpr bool operator > ( const X &lhs, const X &rhs )
+    { return lhs.i_ > rhs.i_ ; }
+
+int main()
+{
+    {
+    typedef X T;
+    typedef optional<T> O;
+
+    constexpr T val(2);
+    constexpr O o1;       // disengaged
+    constexpr O o2{1};    // engaged
+    constexpr O o3{val};  // engaged
+
+    static_assert ( !(o1 > T(1)), "" );
+    static_assert ( !(o2 > T(1)), "" );  // equal
+    static_assert (  (o3 > T(1)), "" );
+    static_assert ( !(o2 >  val), "" );
+    static_assert ( !(o3 >  val), "" );  // equal
+    static_assert ( !(o3 > T(3)), "" );
+
+    static_assert (   (T(1) > o1), "" );
+    static_assert (  !(T(1) > o2), "" ); // equal
+    static_assert (  !(T(1) > o3), "" );
+    static_assert (   (val  > o2), "" );
+    static_assert (  !(val  > o3), "" ); // equal
+    static_assert (   (T(3) > o3), "" );
+    }
+}

test/std/utilities/optional/optional.comp_with_t/greater_equal.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator>=(const optional<T>& x, const T& v);
+// template <class T> constexpr bool operator>=(const T& v, const optional<T>& x);
+
+#include <optional>
+
+using std::optional;
+
+struct X
+{
+    int i_;
+
+    constexpr X(int i) : i_(i) {}
+};
+
+constexpr bool operator >= ( const X &lhs, const X &rhs )
+    { return lhs.i_ >= rhs.i_ ; }
+
+int main()
+{
+    {
+    typedef X T;
+    typedef optional<T> O;
+
+    constexpr T val(2);
+    constexpr O o1;       // disengaged
+    constexpr O o2{1};    // engaged
+    constexpr O o3{val};  // engaged
+
+    static_assert ( !(o1 >= T(1)), "" );
+    static_assert (  (o2 >= T(1)), "" );  // equal
+    static_assert (  (o3 >= T(1)), "" );
+    static_assert ( !(o2 >=  val), "" );
+    static_assert (  (o3 >=  val), "" );  // equal
+    static_assert ( !(o3 >= T(3)), "" );
+
+    static_assert (   (T(1) >= o1), "" );
+    static_assert (   (T(1) >= o2), "" ); // equal
+    static_assert (  !(T(1) >= o3), "" );
+    static_assert (   (val  >= o2), "" );
+    static_assert (   (val  >= o3), "" ); // equal
+    static_assert (   (T(3) >= o3), "" );
+    }
+}

test/std/utilities/optional/optional.comp_with_t/less_equal.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator<=(const optional<T>& x, const T& v);
+// template <class T> constexpr bool operator<=(const T& v, const optional<T>& x);
+
+#include <optional>
+
+using std::optional;
+
+struct X
+{
+    int i_;
+
+    constexpr X(int i) : i_(i) {}
+};
+
+constexpr bool operator <= ( const X &lhs, const X &rhs )
+    { return lhs.i_ <= rhs.i_ ; }
+
+int main()
+{
+    {
+    typedef X T;
+    typedef optional<T> O;
+
+    constexpr T val(2);
+    constexpr O o1;       // disengaged
+    constexpr O o2{1};    // engaged
+    constexpr O o3{val};  // engaged
+
+    static_assert (  (o1 <= T(1)), "" );
+    static_assert (  (o2 <= T(1)), "" );  // equal
+    static_assert ( !(o3 <= T(1)), "" );
+    static_assert (  (o2 <=  val), "" );
+    static_assert (  (o3 <=  val), "" );  // equal
+    static_assert (  (o3 <= T(3)), "" );
+
+    static_assert (  !(T(1) <= o1), "" );
+    static_assert (   (T(1) <= o2), "" ); // equal
+    static_assert (   (T(1) <= o3), "" );
+    static_assert (  !(val  <= o2), "" );
+    static_assert (   (val  <= o3), "" ); // equal
+    static_assert (  !(T(3) <= o3), "" );
+    }
+}

test/std/utilities/optional/optional.comp_with_t/less_than.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator<(const optional<T>& x, const T& v);
+// template <class T> constexpr bool operator<(const T& v, const optional<T>& x);
+
+#include <optional>
+
+using std::optional;
+
+struct X
+{
+    int i_;
+
+    constexpr X(int i) : i_(i) {}
+};
+
+constexpr bool operator < ( const X &lhs, const X &rhs )
+    { return lhs.i_ < rhs.i_ ; }
+
+int main()
+{
+    {
+    typedef X T;
+    typedef optional<T> O;
+
+    constexpr T val(2);
+    constexpr O o1;       // disengaged
+    constexpr O o2{1};    // engaged
+    constexpr O o3{val};  // engaged
+
+    static_assert (  (o1 < T(1)), "" );
+    static_assert ( !(o2 < T(1)), "" );  // equal
+    static_assert ( !(o3 < T(1)), "" );
+    static_assert (  (o2 <  val), "" );
+    static_assert ( !(o3 <  val), "" );  // equal
+    static_assert (  (o3 < T(3)), "" );
+
+    static_assert (  !(T(1) < o1), "" );
+    static_assert (  !(T(1) < o2), "" ); // equal
+    static_assert (   (T(1) < o3), "" );
+    static_assert (  !(val  < o2), "" );
+    static_assert (  !(val  < o3), "" ); // equal
+    static_assert (  !(T(3) < o3), "" );
+    }
+}

test/std/utilities/optional/optional.comp_with_t/not_equal.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator!=(const optional<T>& x, const T& v);
+// template <class T> constexpr bool operator!=(const T& v, const optional<T>& x);
+
+#include <optional>
+
+using std::optional;
+
+struct X
+{
+    int i_;
+
+    constexpr X(int i) : i_(i) {}
+};
+
+constexpr bool operator != ( const X &lhs, const X &rhs )
+    { return lhs.i_ != rhs.i_ ; }
+
+int main()
+{
+    {
+    typedef X T;
+    typedef optional<T> O;
+
+    constexpr T val(2);
+    constexpr O o1;       // disengaged
+    constexpr O o2{1};    // engaged
+    constexpr O o3{val};  // engaged
+
+    static_assert (  (o1 != T(1)), "" );
+    static_assert ( !(o2 != T(1)), "" );
+    static_assert (  (o3 != T(1)), "" );
+    static_assert ( !(o3 != T(2)), "" );
+    static_assert ( !(o3 != val),  "" );
+
+    static_assert (  (T(1) != o1), "" );
+    static_assert ( !(T(1) != o2), "" );
+    static_assert (  (T(1) != o3), "" );
+    static_assert ( !(T(2) != o3), "" );
+    static_assert ( !(val  != o3), "" );
+    }
+}

test/std/utilities/optional/optional.nullops/equal.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator==(const optional<T>& x, nullopt_t) noexcept;
+// template <class T> constexpr bool operator==(nullopt_t, const optional<T>& x) noexcept;
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+    using std::nullopt_t;
+    using std::nullopt;
+
+    {
+    typedef int T;
+    typedef optional<T> O;
+
+    constexpr O o1;     // disengaged
+    constexpr O o2{1};  // engaged
+
+    static_assert (  (nullopt == o1), "" );
+    static_assert ( !(nullopt == o2), "" );
+    static_assert (  (o1 == nullopt), "" );
+    static_assert ( !(o2 == nullopt), "" );
+
+    static_assert (noexcept(nullopt == o1), "");
+    static_assert (noexcept(o1 == nullopt), "");
+    }
+}

test/std/utilities/optional/optional.nullops/greater.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator>(const optional<T>& x, nullopt_t) noexcept;
+// template <class T> constexpr bool operator>(nullopt_t, const optional<T>& x) noexcept;
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+    using std::nullopt_t;
+    using std::nullopt;
+
+    {
+    typedef int T;
+    typedef optional<T> O;
+
+    constexpr O o1;     // disengaged
+    constexpr O o2{1};  // engaged
+
+    static_assert ( !(nullopt > o1), "" );
+    static_assert ( !(nullopt > o2), "" );
+    static_assert ( !(o1 > nullopt), "" );
+    static_assert (  (o2 > nullopt), "" );
+
+    static_assert (noexcept(nullopt > o1), "");
+    static_assert (noexcept(o1 > nullopt), "");
+    }
+}

test/std/utilities/optional/optional.nullops/greater_equal.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator>=(const optional<T>& x, nullopt_t) noexcept;
+// template <class T> constexpr bool operator>=(nullopt_t, const optional<T>& x) noexcept;
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+    using std::nullopt_t;
+    using std::nullopt;
+
+    {
+    typedef int T;
+    typedef optional<T> O;
+
+    constexpr O o1;     // disengaged
+    constexpr O o2{1};  // engaged
+
+    static_assert (  (nullopt >= o1), "" );
+    static_assert ( !(nullopt >= o2), "" );
+    static_assert (  (o1 >= nullopt), "" );
+    static_assert (  (o2 >= nullopt), "" );
+
+    static_assert (noexcept(nullopt >= o1), "");
+    static_assert (noexcept(o1 >= nullopt), "");
+    }
+}

test/std/utilities/optional/optional.nullops/less_equal.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator<=(const optional<T>& x, nullopt_t) noexcept;
+// template <class T> constexpr bool operator<=(nullopt_t, const optional<T>& x) noexcept;
+
+#include <optional>
+
+int main()
+{
+#if _LIBCPP_STD_VER > 11
+    using std::optional;
+    using std::nullopt_t;
+    using std::nullopt;
+
+    {
+    typedef int T;
+    typedef optional<T> O;
+
+    constexpr O o1;     // disengaged
+    constexpr O o2{1};  // engaged
+
+    static_assert (  (nullopt <= o1), "" );
+    static_assert (  (nullopt <= o2), "" );
+    static_assert (  (o1 <= nullopt), "" );
+    static_assert ( !(o2 <= nullopt), "" );
+
+    static_assert (noexcept(nullopt <= o1), "");
+    static_assert (noexcept(o1 <= nullopt), "");
+    }
+#endif
+}

test/std/utilities/optional/optional.nullops/less_than.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator<(const optional<T>& x, nullopt_t) noexcept;
+// template <class T> constexpr bool operator<(nullopt_t, const optional<T>& x) noexcept;
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+    using std::nullopt_t;
+    using std::nullopt;
+
+    {
+    typedef int T;
+    typedef optional<T> O;
+
+    constexpr O o1;     // disengaged
+    constexpr O o2{1};  // engaged
+
+    static_assert ( !(nullopt < o1), "" );
+    static_assert (  (nullopt < o2), "" );
+    static_assert ( !(o1 < nullopt), "" );
+    static_assert ( !(o2 < nullopt), "" );
+
+    static_assert (noexcept(nullopt < o1), "");
+    static_assert (noexcept(o1 < nullopt), "");
+    }
+}

test/std/utilities/optional/optional.nullops/not_equal.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator!=(const optional<T>& x, nullopt_t) noexcept;
+// template <class T> constexpr bool operator!=(nullopt_t, const optional<T>& x) noexcept;
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+    using std::nullopt_t;
+    using std::nullopt;
+
+    {
+    typedef int T;
+    typedef optional<T> O;
+
+    constexpr O o1;     // disengaged
+    constexpr O o2{1};  // engaged
+
+    static_assert ( !(nullopt != o1), "" );
+    static_assert (  (nullopt != o2), "" );
+    static_assert ( !(o1 != nullopt), "" );
+    static_assert (  (o2 != nullopt), "" );
+
+    static_assert (noexcept(nullopt != o1), "");
+    static_assert (noexcept(o1 != nullopt), "");
+    }
+}

test/std/utilities/optional/optional.nullopt/nullopt_t.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// struct nullopt_t{see below};
+// constexpr nullopt_t nullopt(unspecified);
+
+#include <optional>
+#include <type_traits>
+
+using std::optional;
+using std::nullopt_t;
+using std::nullopt;
+
+constexpr
+int
+test(const nullopt_t&)
+{
+    return 3;
+}
+
+int main()
+{
+    static_assert((std::is_class<nullopt_t>::value), "");
+    static_assert((std::is_empty<nullopt_t>::value), "");
+    static_assert((std::is_literal_type<nullopt_t>::value), "");
+    static_assert((!std::is_default_constructible<nullopt_t>::value), "");
+
+    static_assert(test(nullopt) == 3, "");
+}

test/std/utilities/optional/optional.object/optional.object.assign/assign_value.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class U> optional<T>& operator=(U&& v);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+#include <memory>
+
+using std::optional;
+
+struct X
+{
+};
+
+int main()
+{
+    static_assert(std::is_assignable<optional<int>, int>::value, "");
+    static_assert(std::is_assignable<optional<int>, int&>::value, "");
+    static_assert(std::is_assignable<optional<int>&, int>::value, "");
+    static_assert(std::is_assignable<optional<int>&, int&>::value, "");
+    static_assert(std::is_assignable<optional<int>&, const int&>::value, "");
+    static_assert(!std::is_assignable<const optional<int>&, const int&>::value, "");
+    static_assert(!std::is_assignable<optional<int>, X>::value, "");
+    {
+        optional<int> opt;
+        opt = 1;
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == 1);
+    }
+    {
+        optional<int> opt;
+        const int i = 2;
+        opt = i;
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == i);
+    }
+    {
+        optional<int> opt(3);
+        const int i = 2;
+        opt = i;
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == i);
+    }
+    {
+        optional<std::unique_ptr<int>> opt;
+        opt = std::unique_ptr<int>(new int(3));
+        assert(static_cast<bool>(opt) == true);
+        assert(**opt == 3);
+    }
+    {
+        optional<std::unique_ptr<int>> opt(std::unique_ptr<int>(new int(2)));
+        opt = std::unique_ptr<int>(new int(3));
+        assert(static_cast<bool>(opt) == true);
+        assert(**opt == 3);
+    }
+}

test/std/utilities/optional/optional.object/optional.object.assign/const_optional_U.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// From LWG2451:
+// template<class U>
+//   optional<T>& operator=(const optional<U>& rhs);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    static bool throw_now;
+
+    X() = default;
+    X(int)
+    {
+        if (throw_now)
+            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; }
+};
+
+int main()
+{
+    {
+        optional<int> opt;
+        constexpr optional<short> opt2;
+        opt = opt2;
+        static_assert(static_cast<bool>(opt2) == false, "");
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+    }
+    {
+        optional<int> opt;
+        constexpr optional<short> opt2(short{2});
+        opt = opt2;
+        static_assert(static_cast<bool>(opt2) == true, "");
+        static_assert(*opt2 == 2, "");
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+        assert(*opt == *opt2);
+    }
+    {
+        optional<int> opt(3);
+        constexpr optional<short> opt2;
+        opt = opt2;
+        static_assert(static_cast<bool>(opt2) == false, "");
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+    }
+    {
+        optional<int> opt(3);
+        constexpr optional<short> opt2(short{2});
+        opt = opt2;
+        static_assert(static_cast<bool>(opt2) == true, "");
+        static_assert(*opt2 == 2, "");
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+        assert(*opt == *opt2);
+    }
+    {
+        optional<X> opt;
+        optional<int> opt2(42);
+        assert(static_cast<bool>(opt2) == true);
+        try
+        {
+            X::throw_now = true;
+            opt = opt2;
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 6);
+            assert(static_cast<bool>(opt) == false);
+        }
+    }
+}

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

+//===----------------------------------------------------------------------===//
+//
+//                     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 <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    static bool throw_now;
+
+    X() = default;
+    X(const X&)
+    {
+        if (throw_now)
+            throw 6;
+    }
+};
+
+bool X::throw_now = false;
+
+int main()
+{
+    {
+        optional<int> opt;
+        constexpr optional<int> opt2;
+        opt = opt2;
+        static_assert(static_cast<bool>(opt2) == false, "");
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+    }
+    {
+        optional<int> opt;
+        constexpr optional<int> opt2(2);
+        opt = opt2;
+        static_assert(static_cast<bool>(opt2) == true, "");
+        static_assert(*opt2 == 2, "");
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+        assert(*opt == *opt2);
+    }
+    {
+        optional<int> opt(3);
+        constexpr optional<int> opt2;
+        opt = opt2;
+        static_assert(static_cast<bool>(opt2) == false, "");
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+    }
+    {
+        optional<int> opt(3);
+        constexpr optional<int> opt2(2);
+        opt = opt2;
+        static_assert(static_cast<bool>(opt2) == true, "");
+        static_assert(*opt2 == 2, "");
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+        assert(*opt == *opt2);
+    }
+    {
+        optional<X> opt;
+        optional<X> opt2(X{});
+        assert(static_cast<bool>(opt2) == true);
+        try
+        {
+            X::throw_now = true;
+            opt = opt2;
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 6);
+            assert(static_cast<bool>(opt) == false);
+        }
+    }
+}

test/std/utilities/optional/optional.object/optional.object.assign/emplace.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class... Args> void optional<T>::emplace(Args&&... args);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+#include <memory>
+
+using std::optional;
+
+class X
+{
+    int i_;
+    int j_ = 0;
+public:
+    X() : i_(0) {}
+    X(int i) : i_(i) {}
+    X(int i, int j) : i_(i), j_(j) {}
+
+    friend bool operator==(const X& x, const X& y)
+        {return x.i_ == y.i_ && x.j_ == y.j_;}
+};
+
+class Y
+{
+public:
+    static bool dtor_called;
+    Y() = default;
+    Y(int) {throw 6;}
+    ~Y() {dtor_called = true;}
+};
+
+bool Y::dtor_called = false;
+
+int main()
+{
+    {
+        optional<int> opt;
+        opt.emplace();
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == 0);
+    }
+    {
+        optional<int> opt;
+        opt.emplace(1);
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == 1);
+    }
+    {
+        optional<int> opt(2);
+        opt.emplace();
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == 0);
+    }
+    {
+        optional<int> opt(2);
+        opt.emplace(1);
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == 1);
+    }
+    {
+        optional<X> opt;
+        opt.emplace();
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == X());
+    }
+    {
+        optional<X> opt;
+        opt.emplace(1);
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == X(1));
+    }
+    {
+        optional<X> opt;
+        opt.emplace(1, 2);
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == X(1, 2));
+    }
+    {
+        optional<X> opt(X{3});
+        opt.emplace();
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == X());
+    }
+    {
+        optional<X> opt(X{3});
+        opt.emplace(1);
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == X(1));
+    }
+    {
+        optional<X> opt(X{3});
+        opt.emplace(1, 2);
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == X(1, 2));
+    }
+    {
+        Y y;
+        optional<Y> opt(y);
+        assert(Y::dtor_called == false);
+        opt.emplace();
+        assert(Y::dtor_called == true);
+    }
+    Y::dtor_called = false;
+    {
+        Y y;
+        optional<Y> opt(y);
+        try
+        {
+            assert(static_cast<bool>(opt) == true);
+            assert(Y::dtor_called == false);
+            opt.emplace(1);
+        }
+        catch (int i)
+        {
+            assert(i == 6);
+            assert(static_cast<bool>(opt) == false);
+            assert(Y::dtor_called == true);
+        }
+    }
+}

test/std/utilities/optional/optional.object/optional.object.assign/emplace_initializer_list.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class U, class... Args>
+//   void optional<T>::emplace(initializer_list<U> il, Args&&... args);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+#include <vector>
+
+using std::optional;
+
+class X
+{
+    int i_;
+    int j_ = 0;
+public:
+    static bool dtor_called;
+    constexpr X() : i_(0) {}
+    constexpr X(int i) : i_(i) {}
+    constexpr X(std::initializer_list<int> il) : i_(il.begin()[0]), j_(il.begin()[1]) {}
+    ~X() {dtor_called = true;}
+
+    friend constexpr bool operator==(const X& x, const X& y)
+        {return x.i_ == y.i_ && x.j_ == y.j_;}
+};
+
+bool X::dtor_called = false;
+
+class Y
+{
+    int i_;
+    int j_ = 0;
+public:
+    constexpr Y() : i_(0) {}
+    constexpr Y(int i) : i_(i) {}
+    constexpr Y(std::initializer_list<int> il) : i_(il.begin()[0]), j_(il.begin()[1]) {}
+
+    friend constexpr bool operator==(const Y& x, const Y& y)
+        {return x.i_ == y.i_ && x.j_ == y.j_;}
+};
+
+class Z
+{
+    int i_;
+    int j_ = 0;
+public:
+    static bool dtor_called;
+    Z() : i_(0) {}
+    Z(int i) : i_(i) {}
+    Z(std::initializer_list<int> il) : i_(il.begin()[0]), j_(il.begin()[1])
+        {throw 6;}
+    ~Z() {dtor_called = true;}
+
+    friend bool operator==(const Z& x, const Z& y)
+        {return x.i_ == y.i_ && x.j_ == y.j_;}
+};
+
+bool Z::dtor_called = false;
+
+int main()
+{
+    {
+        X x;
+        optional<X> opt(x);
+        assert(X::dtor_called == false);
+        opt.emplace({1, 2});
+        assert(X::dtor_called == true);
+        assert(*opt == X({1, 2}));
+    }
+    {
+        optional<std::vector<int>> opt;
+        opt.emplace({1, 2, 3}, std::allocator<int>());
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == std::vector<int>({1, 2, 3}));
+    }
+    {
+        optional<Y> opt;
+        opt.emplace({1, 2});
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == Y({1, 2}));
+    }
+    {
+        Z z;
+        optional<Z> opt(z);
+        try
+        {
+            assert(static_cast<bool>(opt) == true);
+            assert(Z::dtor_called == false);
+            opt.emplace({1, 2});
+        }
+        catch (int i)
+        {
+            assert(i == 6);
+            assert(static_cast<bool>(opt) == false);
+            assert(Z::dtor_called == true);
+        }
+    }
+}

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

+//===----------------------------------------------------------------------===//
+//
+//                     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)
+//     noexcept(is_nothrow_move_assignable<T>::value &&
+//              is_nothrow_move_constructible<T>::value);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    static bool throw_now;
+
+    X() = default;
+    X(X&&)
+    {
+        if (throw_now)
+            throw 6;
+    }
+    X& operator=(X&&) noexcept
+    {
+        return *this;
+    }
+};
+
+struct Y {};
+
+bool X::throw_now = false;
+
+int main()
+{
+    {
+        static_assert(std::is_nothrow_move_assignable<optional<int>>::value, "");
+        optional<int> opt;
+        constexpr optional<int> opt2;
+        opt = std::move(opt2);
+        static_assert(static_cast<bool>(opt2) == false, "");
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+    }
+    {
+        optional<int> opt;
+        constexpr optional<int> opt2(2);
+        opt = std::move(opt2);
+        static_assert(static_cast<bool>(opt2) == true, "");
+        static_assert(*opt2 == 2, "");
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+        assert(*opt == *opt2);
+    }
+    {
+        optional<int> opt(3);
+        constexpr optional<int> opt2;
+        opt = std::move(opt2);
+        static_assert(static_cast<bool>(opt2) == false, "");
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+    }
+    {
+        optional<int> opt(3);
+        constexpr optional<int> opt2(2);
+        opt = std::move(opt2);
+        static_assert(static_cast<bool>(opt2) == true, "");
+        static_assert(*opt2 == 2, "");
+        assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
+        assert(*opt == *opt2);
+    }
+    {
+        static_assert(!std::is_nothrow_move_assignable<optional<X>>::value, "");
+        optional<X> opt;
+        optional<X> opt2(X{});
+        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);
+        }
+    }
+    {
+        static_assert(std::is_nothrow_move_assignable<optional<Y>>::value, "");
+    }
+}

test/std/utilities/optional/optional.object/optional.object.assign/nullopt_t.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// optional<T>& operator=(nullopt_t) noexcept;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+using std::nullopt_t;
+using std::nullopt;
+
+struct X
+{
+    static bool dtor_called;
+    ~X() {dtor_called = true;}
+};
+
+bool X::dtor_called = false;
+
+int main()
+{
+    {
+        optional<int> opt;
+        static_assert(noexcept(opt = nullopt) == true, "");
+        opt = nullopt;
+        assert(static_cast<bool>(opt) == false);
+    }
+    {
+        optional<int> opt(3);
+        opt = nullopt;
+        assert(static_cast<bool>(opt) == false);
+    }
+    {
+        optional<X> opt;
+        static_assert(noexcept(opt = nullopt) == true, "");
+        assert(X::dtor_called == false);
+        opt = nullopt;
+        assert(X::dtor_called == false);
+        assert(static_cast<bool>(opt) == false);
+    }
+    assert(X::dtor_called == false); // TRANSITION, Clang/C2 VSO#239997
+    {
+        X x;
+        optional<X> opt(x);
+        assert(X::dtor_called == false);
+        opt = nullopt;
+        assert(X::dtor_called == true);
+        assert(static_cast<bool>(opt) == false);
+    }
+}

test/std/utilities/optional/optional.object/optional.object.assign/optional_U.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// From LWG2451:
+// template <class U>
+// optional<T>& operator=(optional<U>&& rhs);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    static bool throw_now;
+
+    X() = default;
+    X(int &&)
+    {
+        if (throw_now)
+            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; }
+};
+
+int main()
+{
+    {
+        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<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);
+        }
+    }
+}

test/std/utilities/optional/optional.object/optional.object.ctor/U.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class U>
+//   constexpr optional(U&& u);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+class X
+{
+    int i_;
+public:
+    X(int i) : i_(i) {}
+
+    friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
+};
+
+class Y
+{
+    int i_;
+public:
+    constexpr Y(int i) : i_(i) {}
+
+    friend constexpr bool operator==(const Y& x, const Y& y) {return x.i_ == y.i_;}
+};
+
+struct Z
+{
+    Z(int) {throw 6;}
+};
+
+template <class To, class From>
+constexpr bool implicit_conversion(optional<To>&& opt, const From& v)
+{
+    return opt && *opt == static_cast<To>(v);
+}
+
+int main()
+{
+    {
+        typedef int T;
+        typedef long long U;
+        constexpr T t(5);
+        static_assert(implicit_conversion<U>(t, t), "");
+
+        struct test_constexpr_ctor
+            : public optional<U>
+        {
+            constexpr test_constexpr_ctor(const T& t)
+                : optional<U>(t)
+            {}
+        };
+    }
+    {
+        typedef double T;
+        typedef long double U;
+        constexpr T t(3.14);
+        static_assert(implicit_conversion<U>(t, t), "");
+
+        struct test_constexpr_ctor
+            : public optional<U>
+        {
+            constexpr test_constexpr_ctor(const T& t)
+                : optional<U>(t)
+            {}
+        };
+    }
+    {
+        assert(implicit_conversion<X>(3, 3));
+    }
+    {
+        static_assert(implicit_conversion<Y>(3, 3), "");
+
+        struct test_constexpr_ctor
+            : public optional<Y>
+        {
+            constexpr test_constexpr_ctor(int i)
+                : optional<Y>(i)
+            {}
+        };
+
+    }
+    {
+        typedef Z T;
+        try
+        {
+            optional<T> opt = 3;
+            (void)opt;
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 6);
+        }
+    }
+
+    static_assert(!(std::is_constructible<optional<X>, Y>::value), "");
+    static_assert(!(std::is_constructible<optional<X>, const Y&>::value), "");
+}

test/std/utilities/optional/optional.object/optional.object.ctor/const_T.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr optional(const T& v);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+class X
+{
+    int i_;
+public:
+    X(int i) : i_(i) {}
+
+    friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
+};
+
+class Y
+{
+    int i_;
+public:
+    constexpr Y(int i) : i_(i) {}
+
+    friend constexpr bool operator==(const Y& x, const Y& y) {return x.i_ == y.i_;}
+};
+
+class Z
+{
+public:
+    Z(int) {}
+    Z(const Z&) {throw 6;}
+};
+
+
+int main()
+{
+    {
+        typedef int T;
+        constexpr T t(5);
+        constexpr optional<T> opt(t);
+        static_assert(static_cast<bool>(opt) == true, "");
+        static_assert(*opt == 5, "");
+
+        struct test_constexpr_ctor
+            : public optional<T>
+        {
+            constexpr test_constexpr_ctor(const T&) {}
+        };
+
+    }
+    {
+        typedef double T;
+        constexpr T t(3);
+        constexpr optional<T> opt(t);
+        static_assert(static_cast<bool>(opt) == true, "");
+        static_assert(*opt == 3, "");
+
+        struct test_constexpr_ctor
+            : public optional<T>
+        {
+            constexpr test_constexpr_ctor(const T&) {}
+        };
+
+    }
+    {
+        typedef X T;
+        const T t(3);
+        optional<T> opt(t);
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == 3);
+    }
+    {
+        typedef Y T;
+        constexpr T t(3);
+        constexpr optional<T> opt(t);
+        static_assert(static_cast<bool>(opt) == true, "");
+        static_assert(*opt == 3, "");
+
+        struct test_constexpr_ctor
+            : public optional<T>
+        {
+            constexpr test_constexpr_ctor(const T&) {}
+        };
+
+    }
+    {
+        typedef Z T;
+        try
+        {
+            const T t(3);
+            optional<T> opt(t);
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 6);
+        }
+    }
+}

test/std/utilities/optional/optional.object/optional.object.ctor/const_optional_U.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class U>
+//   optional(const optional<U>& rhs);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+template <class T, class U>
+void
+test(const optional<U>& rhs, bool is_going_to_throw = false)
+{
+    bool rhs_engaged = static_cast<bool>(rhs);
+    try
+    {
+        optional<T> lhs = rhs;
+        assert(is_going_to_throw == false);
+        assert(static_cast<bool>(lhs) == rhs_engaged);
+        if (rhs_engaged)
+            assert(*lhs == *rhs);
+    }
+    catch (int i)
+    {
+        assert(i == 6);
+    }
+}
+
+class X
+{
+    int i_;
+public:
+    X(int i) : i_(i) {}
+    X(const X& x) : i_(x.i_) {}
+    ~X() {i_ = 0;}
+    friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
+};
+
+class Y
+{
+    int i_;
+public:
+    Y(int i) : i_(i) {}
+
+    friend constexpr bool operator==(const Y& x, const Y& y) {return x.i_ == y.i_;}
+};
+
+int count = 0;
+
+class Z
+{
+    int i_;
+public:
+    Z(int i) : i_(i) {throw 6;}
+
+    friend constexpr bool operator==(const Z& x, const Z& y) {return x.i_ == y.i_;}
+};
+
+
+int main()
+{
+    {
+        typedef short U;
+        typedef int T;
+        optional<U> rhs;
+        test<T>(rhs);
+    }
+    {
+        typedef short U;
+        typedef int T;
+        optional<U> rhs(U{3});
+        test<T>(rhs);
+    }
+    {
+        typedef X T;
+        typedef int U;
+        optional<U> rhs;
+        test<T>(rhs);
+    }
+    {
+        typedef X T;
+        typedef int U;
+        optional<U> rhs(U{3});
+        test<T>(rhs);
+    }
+    {
+        typedef Y T;
+        typedef int U;
+        optional<U> rhs;
+        test<T>(rhs);
+    }
+    {
+        typedef Y T;
+        typedef int U;
+        optional<U> rhs(U{3});
+        test<T>(rhs);
+    }
+    {
+        typedef Z T;
+        typedef int U;
+        optional<U> rhs;
+        test<T>(rhs);
+    }
+    {
+        typedef Z T;
+        typedef int U;
+        optional<U> rhs(U{3});
+        test<T>(rhs, true);
+    }
+
+    static_assert(!(std::is_constructible<optional<X>, const optional<Y>&>::value), "");
+}

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

+//===----------------------------------------------------------------------===//
+//
+//                     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 <type_traits>
+#include <cassert>
+
+using std::optional;
+
+template <class T>
+void
+test(const optional<T>& rhs, bool is_going_to_throw = false)
+{
+    bool rhs_engaged = static_cast<bool>(rhs);
+    try
+    {
+        optional<T> lhs = rhs;
+        assert(is_going_to_throw == false);
+        assert(static_cast<bool>(lhs) == rhs_engaged);
+        if (rhs_engaged)
+            assert(*lhs == *rhs);
+    }
+    catch (int i)
+    {
+        assert(i == 6);
+    }
+}
+
+class X
+{
+    int i_;
+public:
+    X(int i) : i_(i) {}
+    X(const X& x) : i_(x.i_) {}
+    ~X() {i_ = 0;}
+    friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
+};
+
+class Y
+{
+    int i_;
+public:
+    Y(int i) : i_(i) {}
+    Y(const Y& x) : i_(x.i_) {}
+
+    friend constexpr bool operator==(const Y& x, const Y& y) {return x.i_ == y.i_;}
+};
+
+int count = 0;
+
+class Z
+{
+    int i_;
+public:
+    Z(int i) : i_(i) {}
+    Z(const Z&)
+    {
+        if (++count == 2)
+            throw 6;
+    }
+
+    friend constexpr bool operator==(const Z& x, const Z& y) {return x.i_ == y.i_;}
+};
+
+
+int main()
+{
+    {
+        typedef int T;
+        optional<T> rhs;
+        test(rhs);
+    }
+    {
+        typedef int T;
+        optional<T> rhs(3);
+        test(rhs);
+    }
+    {
+        typedef X T;
+        optional<T> rhs;
+        test(rhs);
+    }
+    {
+        typedef X T;
+        optional<T> rhs(X(3));
+        test(rhs);
+    }
+    {
+        typedef Y T;
+        optional<T> rhs;
+        test(rhs);
+    }
+    {
+        typedef Y T;
+        optional<T> rhs(Y(3));
+        test(rhs);
+    }
+    {
+        typedef Z T;
+        optional<T> rhs;
+        test(rhs);
+    }
+    {
+        typedef Z T;
+        optional<T> rhs(Z(3));
+        test(rhs, true);
+    }
+}

test/std/utilities/optional/optional.object/optional.object.ctor/default.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr optional() noexcept;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+template <class Opt>
+void
+test_constexpr()
+{
+    static_assert(std::is_nothrow_default_constructible<Opt>::value, "");
+    constexpr Opt opt;
+    static_assert(static_cast<bool>(opt) == false, "");
+
+    struct test_constexpr_ctor
+        : public Opt
+    {
+        constexpr test_constexpr_ctor() {}
+    };
+}
+
+template <class Opt>
+void
+test()
+{
+    static_assert(std::is_nothrow_default_constructible<Opt>::value, "");
+    Opt opt;
+    assert(static_cast<bool>(opt) == false);
+
+    struct test_constexpr_ctor
+        : public Opt
+    {
+        constexpr test_constexpr_ctor() {}
+    };
+}
+
+struct X
+{
+    X();
+};
+
+int main()
+{
+    test_constexpr<optional<int>>();
+    test_constexpr<optional<int*>>();
+    test<optional<X>>();
+}

test/std/utilities/optional/optional.object/optional.object.ctor/explicit_U.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class U>
+//   explicit constexpr optional(U&& u);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+class X
+{
+    int i_;
+public:
+    explicit X(int i) : i_(i) {}
+
+    friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
+};
+
+class Y
+{
+    int i_;
+public:
+    constexpr explicit Y(int i) : i_(i) {}
+
+    friend constexpr bool operator==(const Y& x, const Y& y) {return x.i_ == y.i_;}
+};
+
+class Z
+{
+public:
+    explicit Z(int) {throw 6;}
+};
+
+
+int main()
+{
+    {
+        typedef X T;
+        static_assert(!(std::is_convertible<int, optional<T>>::value), "");
+        optional<T> opt(3);
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == T(3));
+    }
+    {
+        typedef Y T;
+        static_assert(!(std::is_convertible<int, optional<T>>::value), "");
+        constexpr optional<T> opt(3);
+        static_assert(static_cast<bool>(opt) == true, "");
+        static_assert(*opt == T(3), "");
+
+        struct test_constexpr_ctor
+            : public optional<T>
+        {
+            constexpr test_constexpr_ctor(int i)
+                : optional<T>(i)
+            {}
+        };
+
+    }
+    {
+        typedef Z T;
+        static_assert(!(std::is_convertible<int, optional<T>>::value), "");
+        try
+        {
+            optional<T> opt(3);
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 6);
+        }
+    }
+}

test/std/utilities/optional/optional.object/optional.object.ctor/explicit_const_optional_U.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class U>
+//   explicit optional(const optional<U>& rhs);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+template <class T, class U>
+void
+test(const optional<U>& rhs, bool is_going_to_throw = false)
+{
+    bool rhs_engaged = static_cast<bool>(rhs);
+    try
+    {
+        static_assert(!(std::is_convertible<const optional<U>&, optional<T>>::value), "");
+        optional<T> lhs(rhs);
+        assert(is_going_to_throw == false);
+        assert(static_cast<bool>(lhs) == rhs_engaged);
+        if (rhs_engaged)
+            assert(*lhs == T(*rhs));
+    }
+    catch (int i)
+    {
+        assert(i == 6);
+    }
+}
+
+class X
+{
+    int i_;
+public:
+    explicit X(int i) : i_(i) {}
+    X(const X& x) : i_(x.i_) {}
+    ~X() {i_ = 0;}
+    friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
+};
+
+class Y
+{
+    int i_;
+public:
+    explicit Y(int i) : i_(i) {}
+
+    friend constexpr bool operator==(const Y& x, const Y& y) {return x.i_ == y.i_;}
+};
+
+int count = 0;
+
+class Z
+{
+    int i_;
+public:
+    explicit Z(int i) : i_(i) {throw 6;}
+
+    friend constexpr bool operator==(const Z& x, const Z& y) {return x.i_ == y.i_;}
+};
+
+
+int main()
+{
+    {
+        typedef X T;
+        typedef int U;
+        optional<U> rhs;
+        test<T>(rhs);
+    }
+    {
+        typedef X T;
+        typedef int U;
+        optional<U> rhs(3);
+        test<T>(rhs);
+    }
+    {
+        typedef Y T;
+        typedef int U;
+        optional<U> rhs;
+        test<T>(rhs);
+    }
+    {
+        typedef Y T;
+        typedef int U;
+        optional<U> rhs(3);
+        test<T>(rhs);
+    }
+    {
+        typedef Z T;
+        typedef int U;
+        optional<U> rhs;
+        test<T>(rhs);
+    }
+    {
+        typedef Z T;
+        typedef int U;
+        optional<U> rhs(3);
+        test<T>(rhs, true);
+    }
+}

test/std/utilities/optional/optional.object/optional.object.ctor/explicit_optional_U.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class U>
+//   explicit optional(optional<U>&& rhs);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+template <class T, class U>
+void
+test(optional<U>&& rhs, bool is_going_to_throw = false)
+{
+    bool rhs_engaged = static_cast<bool>(rhs);
+    try
+    {
+        static_assert(!(std::is_convertible<optional<U>&&, optional<T>>::value), "");
+        optional<T> lhs(std::move(rhs));
+        assert(is_going_to_throw == false);
+        assert(static_cast<bool>(lhs) == rhs_engaged);
+    }
+    catch (int i)
+    {
+        assert(i == 6);
+    }
+}
+
+class X
+{
+    int i_;
+public:
+    explicit X(int i) : i_(i) {}
+    X(X&& x) : i_(std::exchange(x.i_, 0)) {}
+    ~X() {i_ = 0;}
+    friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
+};
+
+int count = 0;
+
+class Z
+{
+public:
+    explicit Z(int) { throw 6; }
+};
+
+int main()
+{
+    {
+        optional<int> rhs;
+        test<X>(std::move(rhs));
+    }
+    {
+        optional<int> rhs(3);
+        test<X>(std::move(rhs));
+    }
+    {
+        optional<int> rhs;
+        test<Z>(std::move(rhs));
+    }
+    {
+        optional<int> rhs(3);
+        test<Z>(std::move(rhs), true);
+    }
+}

test/std/utilities/optional/optional.object/optional.object.ctor/in_place_t.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class... Args>
+//   constexpr explicit optional(in_place_t, Args&&... args);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+
+using std::optional;
+using std::in_place_t;
+using std::in_place;
+
+class X
+{
+    int i_;
+    int j_ = 0;
+public:
+    X() : i_(0) {}
+    X(int i) : i_(i) {}
+    X(int i, int j) : i_(i), j_(j) {}
+
+    ~X() {}
+
+    friend bool operator==(const X& x, const X& y)
+        {return x.i_ == y.i_ && x.j_ == y.j_;}
+};
+
+class Y
+{
+    int i_;
+    int j_ = 0;
+public:
+    constexpr Y() : i_(0) {}
+    constexpr Y(int i) : i_(i) {}
+    constexpr Y(int i, int j) : i_(i), j_(j) {}
+
+    friend constexpr bool operator==(const Y& x, const Y& y)
+        {return x.i_ == y.i_ && x.j_ == y.j_;}
+};
+
+class Z
+{
+public:
+    Z(int i) {throw 6;}
+};
+
+
+int main()
+{
+    {
+        constexpr optional<int> opt(in_place, 5);
+        static_assert(static_cast<bool>(opt) == true, "");
+        static_assert(*opt == 5, "");
+
+        struct test_constexpr_ctor
+            : public optional<int>
+        {
+            constexpr test_constexpr_ctor(in_place_t, int i)
+                : optional<int>(in_place, i) {}
+        };
+
+    }
+    {
+        const optional<X> opt(in_place);
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == X());
+    }
+    {
+        const optional<X> opt(in_place, 5);
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == X(5));
+    }
+    {
+        const optional<X> opt(in_place, 5, 4);
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == X(5, 4));
+    }
+    {
+        constexpr optional<Y> opt(in_place);
+        static_assert(static_cast<bool>(opt) == true, "");
+        static_assert(*opt == Y(), "");
+
+        struct test_constexpr_ctor
+            : public optional<Y>
+        {
+            constexpr test_constexpr_ctor(in_place_t)
+                : optional<Y>(in_place) {}
+        };
+
+    }
+    {
+        constexpr optional<Y> opt(in_place, 5);
+        static_assert(static_cast<bool>(opt) == true, "");
+        static_assert(*opt == Y(5), "");
+
+        struct test_constexpr_ctor
+            : public optional<Y>
+        {
+            constexpr test_constexpr_ctor(in_place_t, int i)
+                : optional<Y>(in_place, i) {}
+        };
+
+    }
+    {
+        constexpr optional<Y> opt(in_place, 5, 4);
+        static_assert(static_cast<bool>(opt) == true, "");
+        static_assert(*opt == Y(5, 4), "");
+
+        struct test_constexpr_ctor
+            : public optional<Y>
+        {
+            constexpr test_constexpr_ctor(in_place_t, int i, int j)
+                : optional<Y>(in_place, i, j) {}
+        };
+
+    }
+    {
+        try
+        {
+            const optional<Z> opt(in_place, 1);
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 6);
+        }
+    }
+}

test/std/utilities/optional/optional.object/optional.object.ctor/initializer_list.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class U, class... Args>
+//     constexpr
+//     explicit optional(in_place_t, initializer_list<U> il, Args&&... args);
+
+#include <optional>
+#include <type_traits>
+#include <vector>
+#include <cassert>
+
+using std::optional;
+using std::in_place_t;
+using std::in_place;
+
+class X
+{
+    int i_;
+    int j_ = 0;
+public:
+    X() : i_(0) {}
+    X(int i) : i_(i) {}
+    X(int i, int j) : i_(i), j_(j) {}
+
+    ~X() {}
+
+    friend bool operator==(const X& x, const X& y)
+        {return x.i_ == y.i_ && x.j_ == y.j_;}
+};
+
+class Y
+{
+    int i_;
+    int j_ = 0;
+public:
+    constexpr Y() : i_(0) {}
+    constexpr Y(int i) : i_(i) {}
+    constexpr Y(std::initializer_list<int> il) : i_(il.begin()[0]), j_(il.begin()[1]) {}
+
+    friend constexpr bool operator==(const Y& x, const Y& y)
+        {return x.i_ == y.i_ && x.j_ == y.j_;}
+};
+
+class Z
+{
+    int i_;
+    int j_ = 0;
+public:
+    Z() : i_(0) {}
+    Z(int i) : i_(i) {}
+    Z(std::initializer_list<int> il) : i_(il.begin()[0]), j_(il.begin()[1])
+        {throw 6;}
+
+    friend bool operator==(const Z& x, const Z& y)
+        {return x.i_ == y.i_ && x.j_ == y.j_;}
+};
+
+int main()
+{
+    {
+        static_assert(!std::is_constructible<X, std::initializer_list<int>&>::value, "");
+        static_assert(!std::is_constructible<optional<X>, std::initializer_list<int>&>::value, "");
+    }
+    {
+        optional<std::vector<int>> opt(in_place, {3, 1});
+        assert(static_cast<bool>(opt) == true);
+        assert((*opt == std::vector<int>{3, 1}));
+        assert(opt->size() == 2);
+    }
+    {
+        optional<std::vector<int>> opt(in_place, {3, 1}, std::allocator<int>());
+        assert(static_cast<bool>(opt) == true);
+        assert((*opt == std::vector<int>{3, 1}));
+        assert(opt->size() == 2);
+    }
+    {
+        static_assert(std::is_constructible<optional<Y>, std::initializer_list<int>&>::value, "");
+        constexpr optional<Y> opt(in_place, {3, 1});
+        static_assert(static_cast<bool>(opt) == true, "");
+        static_assert(*opt == Y{3, 1}, "");
+
+        struct test_constexpr_ctor
+            : public optional<Y>
+        {
+            constexpr test_constexpr_ctor(in_place_t, std::initializer_list<int> i)
+                : optional<Y>(in_place, i) {}
+        };
+
+    }
+    {
+        static_assert(std::is_constructible<optional<Z>, std::initializer_list<int>&>::value, "");
+        try
+        {
+            optional<Z> opt(in_place, {3, 1});
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 6);
+        }
+    }
+}

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

+//===----------------------------------------------------------------------===//
+//
+//                     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) noexcept(is_nothrow_move_constructible<T>::value);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+template <class T>
+void
+test(optional<T>& rhs, bool is_going_to_throw = false)
+{
+    static_assert(std::is_nothrow_move_constructible<optional<T>>::value ==
+                  std::is_nothrow_move_constructible<T>::value, "");
+    bool rhs_engaged = static_cast<bool>(rhs);
+    try
+    {
+        optional<T> lhs = std::move(rhs);
+        assert(is_going_to_throw == false);
+        assert(static_cast<bool>(lhs) == rhs_engaged);
+    }
+    catch (int i)
+    {
+        assert(i == 6);
+    }
+}
+
+class X
+{
+    int i_;
+public:
+    X(int i) : i_(i) {}
+    X(X&& x) : i_(x.i_) {x.i_ = 0;}
+    ~X() {i_ = 0;}
+    friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
+};
+
+class Y
+{
+    int i_;
+public:
+    Y(int i) : i_(i) {}
+    Y(Y&& x) noexcept : i_(x.i_) {x.i_ = 0;}
+
+    friend constexpr bool operator==(const Y& x, const Y& y) {return x.i_ == y.i_;}
+};
+
+int count = 0;
+
+class Z
+{
+    int i_;
+public:
+    Z(int i) : i_(i) {}
+    Z(Z&&)
+    {
+        if (++count == 2)
+            throw 6;
+    }
+
+    friend constexpr bool operator==(const Z& x, const Z& y) {return x.i_ == y.i_;}
+};
+
+int main()
+{
+    {
+        typedef int T;
+        optional<T> rhs;
+        test(rhs);
+    }
+    {
+        typedef int T;
+        optional<T> rhs(3);
+        test(rhs);
+    }
+    {
+        typedef X T;
+        optional<T> rhs;
+        test(rhs);
+    }
+    {
+        typedef X T;
+        optional<T> rhs(X(3));
+        test(rhs);
+    }
+    {
+        typedef Y T;
+        optional<T> rhs;
+        test(rhs);
+    }
+    {
+        typedef Y T;
+        optional<T> rhs(Y(3));
+        test(rhs);
+    }
+    {
+        typedef Z T;
+        optional<T> rhs;
+        test(rhs);
+    }
+    {
+        typedef Z T;
+        optional<T> rhs(Z(3));
+        test(rhs, true);
+    }
+}

test/std/utilities/optional/optional.object/optional.object.ctor/nullopt_t.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr optional(nullopt_t) noexcept;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+using std::nullopt_t;
+using std::nullopt;
+
+template <class Opt>
+void
+test_constexpr()
+{
+    static_assert(noexcept(Opt(nullopt)), "");
+    constexpr Opt opt(nullopt);
+    static_assert(static_cast<bool>(opt) == false, "");
+
+    struct test_constexpr_ctor
+        : public Opt
+    {
+        constexpr test_constexpr_ctor() {}
+    };
+}
+
+template <class Opt>
+void
+test()
+{
+    static_assert(noexcept(Opt(nullopt)), "");
+    Opt opt(nullopt);
+    assert(static_cast<bool>(opt) == false);
+
+    struct test_constexpr_ctor
+        : public Opt
+    {
+        constexpr test_constexpr_ctor() {}
+    };
+}
+
+struct X
+{
+    X();
+};
+
+int main()
+{
+    test_constexpr<optional<int>>();
+    test_constexpr<optional<int*>>();
+    test<optional<X>>();
+}

test/std/utilities/optional/optional.object/optional.object.ctor/optional_U.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class U>
+//   optional(optional<U>&& rhs);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+template <class T, class U>
+void
+test(optional<U>&& rhs, bool is_going_to_throw = false)
+{
+    bool rhs_engaged = static_cast<bool>(rhs);
+    try
+    {
+        optional<T> lhs = std::move(rhs);
+        assert(is_going_to_throw == false);
+        assert(static_cast<bool>(lhs) == rhs_engaged);
+    }
+    catch (int i)
+    {
+        assert(i == 6);
+    }
+}
+
+class X
+{
+    int i_;
+public:
+    X(int i) : i_(i) {}
+    X(X&& x) : i_(std::exchange(x.i_, 0)) {}
+    ~X() {i_ = 0;}
+    friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
+};
+
+int count = 0;
+
+struct Z
+{
+    Z(int) { throw 6; }
+};
+
+int main()
+{
+    {
+        optional<short> rhs;
+        test<int>(std::move(rhs));
+    }
+    {
+        optional<short> rhs(short{3});
+        test<int>(std::move(rhs));
+    }
+    {
+        optional<int> rhs;
+        test<X>(std::move(rhs));
+    }
+    {
+        optional<int> rhs(3);
+        test<X>(std::move(rhs));
+    }
+    {
+        optional<int> rhs;
+        test<Z>(std::move(rhs));
+    }
+    {
+        optional<int> rhs(3);
+        test<Z>(std::move(rhs), true);
+    }
+
+    static_assert(!(std::is_constructible<optional<X>, optional<Z>>::value), "");
+}

test/std/utilities/optional/optional.object/optional.object.ctor/rvalue_T.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr optional(T&& v);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+class X
+{
+    int i_;
+public:
+    X(int i) : i_(i) {}
+    X(X&& x) : i_(x.i_) {}
+
+    friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
+};
+
+class Y
+{
+    int i_;
+public:
+    constexpr Y(int i) : i_(i) {}
+    constexpr Y(Y&& x) : i_(x.i_) {}
+
+    friend constexpr bool operator==(const Y& x, const Y& y) {return x.i_ == y.i_;}
+};
+
+class Z
+{
+public:
+    Z(int) {}
+    Z(Z&&) {throw 6;}
+};
+
+
+int main()
+{
+    {
+        typedef int T;
+        constexpr optional<T> opt(T(5));
+        static_assert(static_cast<bool>(opt) == true, "");
+        static_assert(*opt == 5, "");
+
+        struct test_constexpr_ctor
+            : public optional<T>
+        {
+            constexpr test_constexpr_ctor(T&&) {}
+        };
+    }
+    {
+        typedef double T;
+        constexpr optional<T> opt(T(3));
+        static_assert(static_cast<bool>(opt) == true, "");
+        static_assert(*opt == 3, "");
+
+        struct test_constexpr_ctor
+            : public optional<T>
+        {
+            constexpr test_constexpr_ctor(T&&) {}
+        };
+    }
+    {
+        typedef X T;
+        optional<T> opt(T(3));
+        assert(static_cast<bool>(opt) == true);
+        assert(*opt == 3);
+    }
+    {
+        typedef Y T;
+        constexpr optional<T> opt(T(3));
+        static_assert(static_cast<bool>(opt) == true, "");
+        static_assert(*opt == 3, "");
+
+        struct test_constexpr_ctor
+            : public optional<T>
+        {
+            constexpr test_constexpr_ctor(T&&) {}
+        };
+    }
+    {
+        typedef Z T;
+        try
+        {
+            optional<T> opt(T(3));
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 6);
+        }
+    }
+}

test/std/utilities/optional/optional.object/optional.object.dtor/dtor.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// ~optional();
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+class X
+{
+public:
+    static bool dtor_called;
+    X() = default;
+    ~X() {dtor_called = true;}
+};
+
+bool X::dtor_called = false;
+
+int main()
+{
+    {
+        typedef int T;
+        static_assert(std::is_trivially_destructible<T>::value, "");
+        static_assert(std::is_trivially_destructible<optional<T>>::value, "");
+    }
+    {
+        typedef double T;
+        static_assert(std::is_trivially_destructible<T>::value, "");
+        static_assert(std::is_trivially_destructible<optional<T>>::value, "");
+    }
+    {
+        typedef X T;
+        static_assert(!std::is_trivially_destructible<T>::value, "");
+        static_assert(!std::is_trivially_destructible<optional<T>>::value, "");
+        {
+            X x;
+            optional<X> opt{x};
+            assert(X::dtor_called == false);
+        }
+        assert(X::dtor_called == true);
+    }
+}

test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// void reset() noexcept;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    static bool dtor_called;
+    ~X() {dtor_called = true;}
+};
+
+bool X::dtor_called = false;
+
+int main()
+{
+    {
+        optional<int> opt;
+        static_assert(noexcept(opt.reset()) == true, "");
+        opt.reset();
+        assert(static_cast<bool>(opt) == false);
+    }
+    {
+        optional<int> opt(3);
+        opt.reset();
+        assert(static_cast<bool>(opt) == false);
+    }
+    {
+        optional<X> opt;
+        static_assert(noexcept(opt.reset()) == true, "");
+        assert(X::dtor_called == false);
+        opt.reset();
+        assert(X::dtor_called == false);
+        assert(static_cast<bool>(opt) == false);
+    }
+    assert(X::dtor_called == false); // TRANSITION, Clang/C2 VSO#239997
+    {
+        X x;
+        optional<X> opt(x);
+        assert(X::dtor_called == false);
+        opt.reset();
+        assert(X::dtor_called == true);
+        assert(static_cast<bool>(opt) == false);
+    }
+}

test/std/utilities/optional/optional.object/optional.object.observe/bool.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr explicit optional<T>::operator bool() const noexcept;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+int main()
+{
+    using std::optional;
+
+    {
+        constexpr optional<int> opt;
+        static_assert(!opt, "");
+    }
+    {
+        constexpr optional<int> opt(0);
+        static_assert(opt, "");
+    }
+}

test/std/utilities/optional/optional.object/optional.object.observe/dereference.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr T& optional<T>::operator*() &;
+
+#ifdef _LIBCPP_DEBUG
+#define _LIBCPP_ASSERT(x, m) ((x) ? (void)0 : std::exit(0))
+#endif
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    constexpr int test() const& {return 3;}
+    int test() & {return 4;}
+    constexpr int test() const&& {return 5;}
+    int test() && {return 6;}
+};
+
+#if __cplusplus >= 201402
+struct Y
+{
+    constexpr int test() {return 7;}
+};
+
+constexpr int
+test()
+{
+    optional<Y> opt{Y{}};
+    return (*opt).test();
+}
+#endif
+
+int main()
+{
+    {
+        optional<X> opt(X{});
+        assert((*opt).test() == 4);
+    }
+#if __cplusplus >= 201402
+    static_assert(test() == 7, "");
+#endif
+#ifdef _LIBCPP_DEBUG
+    {
+        optional<X> opt;
+        assert((*opt).test() == 3);
+        assert(false);
+    }
+#endif  // _LIBCPP_DEBUG
+}

test/std/utilities/optional/optional.object/optional.object.observe/dereference_const.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr const T& optional<T>::operator*() const &;
+
+#ifdef _LIBCPP_DEBUG
+#define _LIBCPP_ASSERT(x, m) ((x) ? (void)0 : std::exit(0))
+#endif
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    constexpr int test() const& {return 3;}
+    int test() & {return 4;}
+    constexpr int test() const&& {return 5;}
+    int test() && {return 6;}
+};
+
+struct Y
+{
+    int test() const {return 2;}
+};
+
+int main()
+{
+    {
+        constexpr optional<X> opt(X{});
+        static_assert((*opt).test() == 3, "");
+    }
+    {
+        constexpr optional<Y> opt(Y{});
+        assert((*opt).test() == 2);
+    }
+#ifdef _LIBCPP_DEBUG
+    {
+        const optional<X> opt;
+        assert((*opt).test() == 3);
+        assert(false);
+    }
+#endif  // _LIBCPP_DEBUG
+}

test/std/utilities/optional/optional.object/optional.object.observe/dereference_const_rvalue.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr T&& optional<T>::operator*() const &&;
+
+#ifdef _LIBCPP_DEBUG
+#define _LIBCPP_ASSERT(x, m) ((x) ? (void)0 : std::exit(0))
+#endif
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    constexpr int test() const& {return 3;}
+    int test() & {return 4;}
+    constexpr int test() const&& {return 5;}
+    int test() && {return 6;}
+};
+
+struct Y
+{
+    int test() const && {return 2;}
+};
+
+int main()
+{
+    {
+        constexpr optional<X> opt(X{});
+        static_assert((*std::move(opt)).test() == 5, "");
+    }
+    {
+        constexpr optional<Y> opt(Y{});
+        assert((*std::move(opt)).test() == 2);
+    }
+#ifdef _LIBCPP_DEBUG
+    {
+        optional<X> opt;
+        assert((*std::move(opt)).test() == 5);
+        assert(false);
+    }
+#endif  // _LIBCPP_DEBUG
+}

test/std/utilities/optional/optional.object/optional.object.observe/dereference_rvalue.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr T&& optional<T>::operator*() &&;
+
+#ifdef _LIBCPP_DEBUG
+#define _LIBCPP_ASSERT(x, m) ((x) ? (void)0 : std::exit(0))
+#endif
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    constexpr int test() const& {return 3;}
+    int test() & {return 4;}
+    constexpr int test() const&& {return 5;}
+    int test() && {return 6;}
+};
+
+#if __cplusplus >= 201402
+struct Y
+{
+    constexpr int test() && {return 7;}
+};
+
+constexpr int
+test()
+{
+    optional<Y> opt{Y{}};
+    return (*std::move(opt)).test();
+}
+#endif
+
+int main()
+{
+    {
+        optional<X> opt(X{});
+        assert((*std::move(opt)).test() == 6);
+    }
+#if __cplusplus >= 201402
+    static_assert(test() == 7, "");
+#endif
+#ifdef _LIBCPP_DEBUG
+    {
+        optional<X> opt;
+        assert((*std::move(opt)).test() == 3);
+        assert(false);
+    }
+#endif  // _LIBCPP_DEBUG
+}

test/std/utilities/optional/optional.object/optional.object.observe/has_value.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr bool optional<T>::has_value() const noexcept;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+int main()
+{
+    using std::optional;
+
+    {
+        constexpr optional<int> opt;
+        static_assert(!opt.has_value(), "");
+    }
+    {
+        constexpr optional<int> opt(0);
+        static_assert(opt.has_value(), "");
+    }
+}

test/std/utilities/optional/optional.object/optional.object.observe/op_arrow.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr T* optional<T>::operator->();
+
+#ifdef _LIBCPP_DEBUG
+#define _LIBCPP_ASSERT(x, m) ((x) ? (void)0 : std::exit(0))
+#endif
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    int test() {return 3;}
+};
+
+#if __cplusplus >= 201402
+struct Y
+{
+    constexpr int test() {return 3;}
+};
+
+constexpr int
+test()
+{
+    optional<Y> opt{Y{}};
+    return opt->test();
+}
+#endif
+
+int main()
+{
+    {
+        optional<X> opt(X{});
+        assert(opt->test() == 3);
+    }
+#if __cplusplus >= 201402
+    static_assert(test() == 3, "");
+#endif
+#ifdef _LIBCPP_DEBUG
+    {
+        optional<X> opt;
+        assert(opt->test() == 3);
+        assert(false);
+    }
+#endif  // _LIBCPP_DEBUG
+}

test/std/utilities/optional/optional.object/optional.object.observe/op_arrow_const.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr const T* optional<T>::operator->() const;
+
+#ifdef _LIBCPP_DEBUG
+#define _LIBCPP_ASSERT(x, m) ((x) ? (void)0 : std::exit(0))
+#endif
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    constexpr int test() const {return 3;}
+};
+
+struct Y
+{
+    int test() const {return 2;}
+};
+
+struct Z
+{
+    const Z* operator&() const;
+    constexpr int test() const {return 1;}
+};
+
+int main()
+{
+    {
+        constexpr optional<X> opt(X{});
+        static_assert(opt->test() == 3, "");
+    }
+    {
+        constexpr optional<Y> opt(Y{});
+        assert(opt->test() == 2);
+    }
+    {
+        constexpr optional<Z> opt(Z{});
+        static_assert(opt->test() == 1, "");
+    }
+#ifdef _LIBCPP_DEBUG
+    {
+        const optional<X> opt;
+        assert(opt->test() == 3);
+        assert(false);
+    }
+#endif  // _LIBCPP_DEBUG
+}

test/std/utilities/optional/optional.object/optional.object.observe/value.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr T& optional<T>::value() &;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+using std::bad_optional_access;
+
+struct X
+{
+    X() = default;
+    X(const X&) = delete;
+    constexpr int test() const & {return 3;}
+    int test() & {return 4;}
+    constexpr int test() const && {return 5;}
+    int test() && {return 6;}
+};
+
+#if __cplusplus >= 201402
+struct Y
+{
+    constexpr int test() & {return 7;}
+};
+
+constexpr int
+test()
+{
+    optional<Y> opt{Y{}};
+    return opt.value().test();
+}
+#endif
+
+int main()
+{
+    {
+        optional<X> opt;
+        opt.emplace();
+        assert(opt.value().test() == 4);
+    }
+    {
+        optional<X> opt;
+        try
+        {
+            opt.value();
+            assert(false);
+        }
+        catch (const bad_optional_access&)
+        {
+        }
+    }
+#if __cplusplus >= 201402
+    static_assert(test() == 7, "");
+#endif
+}

test/std/utilities/optional/optional.object/optional.object.observe/value_const.fail.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr const T& optional<T>::value() const &;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    constexpr int test() const {return 3;}
+    int test() {return 4;}
+};
+
+int main()
+{
+    {
+        constexpr optional<X> opt;
+        static_assert(opt.value().test() == 3, "");
+    }
+}

test/std/utilities/optional/optional.object/optional.object.observe/value_const.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr const T& optional<T>::value() const &;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+using std::in_place_t;
+using std::in_place;
+using std::bad_optional_access;
+
+struct X
+{
+    X() = default;
+    X(const X&) = delete;
+    constexpr int test() const & {return 3;}
+    int test() & {return 4;}
+    constexpr int test() const && {return 5;}
+    int test() && {return 6;}
+};
+
+int main()
+{
+    {
+        constexpr optional<X> opt(in_place);
+        static_assert(opt.value().test() == 3, "");
+    }
+    {
+        const optional<X> opt(in_place);
+        assert(opt.value().test() == 3);
+    }
+    {
+        const optional<X> opt;
+        try
+        {
+            opt.value();
+            assert(false);
+        }
+        catch (const bad_optional_access&)
+        {
+        }
+    }
+}

test/std/utilities/optional/optional.object/optional.object.observe/value_const_rvalue.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr const T& optional<T>::value() const &&;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+using std::in_place_t;
+using std::in_place;
+using std::bad_optional_access;
+
+struct X
+{
+    X() = default;
+    X(const X&) = delete;
+    constexpr int test() const & {return 3;}
+    int test() & {return 4;}
+    constexpr int test() const && {return 5;}
+    int test() && {return 6;}
+};
+
+int main()
+{
+    {
+        constexpr optional<X> opt(in_place);
+        static_assert(std::move(opt).value().test() == 5, "");
+    }
+    {
+        const optional<X> opt(in_place);
+        assert(std::move(opt).value().test() == 5);
+    }
+    {
+        const optional<X> opt;
+        try
+        {
+            std::move(opt).value();
+            assert(false);
+        }
+        catch (const bad_optional_access&)
+        {
+        }
+    }
+}

test/std/utilities/optional/optional.object/optional.object.observe/value_or.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class U> T optional<T>::value_or(U&& v) &&;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+using std::in_place_t;
+using std::in_place;
+
+struct Y
+{
+    int i_;
+
+    Y(int i) : i_(i) {}
+};
+
+struct X
+{
+    int i_;
+
+    X(int i) : i_(i) {}
+    X(X&& x) : i_(x.i_) {x.i_ = 0;}
+    X(const Y& y) : i_(y.i_) {}
+    X(Y&& y) : i_(y.i_+1) {}
+    friend constexpr bool operator==(const X& x, const X& y)
+        {return x.i_ == y.i_;}
+};
+
+int main()
+{
+    {
+        optional<X> opt(in_place, 2);
+        Y y(3);
+        assert(std::move(opt).value_or(y) == 2);
+        assert(*opt == 0);
+    }
+    {
+        optional<X> opt(in_place, 2);
+        assert(std::move(opt).value_or(Y(3)) == 2);
+        assert(*opt == 0);
+    }
+    {
+        optional<X> opt;
+        Y y(3);
+        assert(std::move(opt).value_or(y) == 3);
+        assert(!opt);
+    }
+    {
+        optional<X> opt;
+        assert(std::move(opt).value_or(Y(3)) == 4);
+        assert(!opt);
+    }
+}

test/std/utilities/optional/optional.object/optional.object.observe/value_or_const.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class U> constexpr T optional<T>::value_or(U&& v) const&;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct Y
+{
+    int i_;
+
+    constexpr Y(int i) : i_(i) {}
+};
+
+struct X
+{
+    int i_;
+
+    constexpr X(int i) : i_(i) {}
+    constexpr X(const Y& y) : i_(y.i_) {}
+    constexpr X(Y&& y) : i_(y.i_+1) {}
+    friend constexpr bool operator==(const X& x, const X& y)
+        {return x.i_ == y.i_;}
+};
+
+int main()
+{
+    {
+        constexpr optional<X> opt(2);
+        constexpr Y y(3);
+        static_assert(opt.value_or(y) == 2, "");
+    }
+    {
+        constexpr optional<X> opt(2);
+        static_assert(opt.value_or(Y(3)) == 2, "");
+    }
+    {
+        constexpr optional<X> opt;
+        constexpr Y y(3);
+        static_assert(opt.value_or(y) == 3, "");
+    }
+    {
+        constexpr optional<X> opt;
+        static_assert(opt.value_or(Y(3)) == 4, "");
+    }
+    {
+        const optional<X> opt(2);
+        const Y y(3);
+        assert(opt.value_or(y) == 2);
+    }
+    {
+        const optional<X> opt(2);
+        assert(opt.value_or(Y(3)) == 2);
+    }
+    {
+        const optional<X> opt;
+        const Y y(3);
+        assert(opt.value_or(y) == 3);
+    }
+    {
+        const optional<X> opt;
+        assert(opt.value_or(Y(3)) == 4);
+    }
+}

test/std/utilities/optional/optional.object/optional.object.observe/value_rvalue.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// constexpr T& optional<T>::value() &&;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+using std::bad_optional_access;
+
+struct X
+{
+    X() = default;
+    X(const X&) = delete;
+    constexpr int test() const & {return 3;}
+    int test() & {return 4;}
+    constexpr int test() const && {return 5;}
+    int test() && {return 6;}
+};
+
+#if __cplusplus >= 201402
+struct Y
+{
+    constexpr int test() && {return 7;}
+};
+
+constexpr int
+test()
+{
+    optional<Y> opt{Y{}};
+    return std::move(opt).value().test();
+}
+#endif
+
+int main()
+{
+    {
+        optional<X> opt;
+        opt.emplace();
+        assert(std::move(opt).value().test() == 6);
+    }
+    {
+        optional<X> opt;
+        try
+        {
+            std::move(opt).value();
+            assert(false);
+        }
+        catch (const bad_optional_access&)
+        {
+        }
+    }
+#if __cplusplus >= 201402
+    static_assert(test() == 7, "");
+#endif
+}

test/std/utilities/optional/optional.object/optional.object.swap/swap.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// void swap(optional&)
+//     noexcept(is_nothrow_move_constructible<T>::value &&
+//              is_nothrow_swappable<T>::value)
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+class X
+{
+    int i_;
+public:
+    static unsigned dtor_called;
+    X(int i) : i_(i) {}
+    X(X&& x) = default;
+    X& operator=(X&&) = default;
+    ~X() {++dtor_called;}
+
+    friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
+};
+
+unsigned X::dtor_called = 0;
+
+class Y
+{
+    int i_;
+public:
+    static unsigned dtor_called;
+    Y(int i) : i_(i) {}
+    Y(Y&&) = default;
+    ~Y() {++dtor_called;}
+
+    friend constexpr bool operator==(const Y& x, const Y& y) {return x.i_ == y.i_;}
+    friend void swap(Y& x, Y& y) {std::swap(x.i_, y.i_);}
+};
+
+unsigned Y::dtor_called = 0;
+
+class Z
+{
+    int i_;
+public:
+    Z(int i) : i_(i) {}
+    Z(Z&&) {throw 7;}
+
+    friend constexpr bool operator==(const Z& x, const Z& y) {return x.i_ == y.i_;}
+    friend void swap(Z& x, Z& y) {throw 6;}
+};
+
+int main()
+{
+    {
+        optional<int> opt1;
+        optional<int> opt2;
+        static_assert(noexcept(opt1.swap(opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+        opt1.swap(opt2);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+    }
+    {
+        optional<int> opt1(1);
+        optional<int> opt2;
+        static_assert(noexcept(opt1.swap(opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == false);
+        opt1.swap(opt2);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 1);
+    }
+    {
+        optional<int> opt1;
+        optional<int> opt2(2);
+        static_assert(noexcept(opt1.swap(opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        opt1.swap(opt2);
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 2);
+        assert(static_cast<bool>(opt2) == false);
+    }
+    {
+        optional<int> opt1(1);
+        optional<int> opt2(2);
+        static_assert(noexcept(opt1.swap(opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        opt1.swap(opt2);
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 2);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 1);
+    }
+    {
+        optional<X> opt1;
+        optional<X> opt2;
+        static_assert(noexcept(opt1.swap(opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+        opt1.swap(opt2);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+        assert(X::dtor_called == 0);
+    }
+    {
+        optional<X> opt1(1);
+        optional<X> opt2;
+        static_assert(noexcept(opt1.swap(opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == false);
+        X::dtor_called = 0;
+        opt1.swap(opt2);
+        assert(X::dtor_called == 1);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 1);
+    }
+    {
+        optional<X> opt1;
+        optional<X> opt2(2);
+        static_assert(noexcept(opt1.swap(opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        X::dtor_called = 0;
+        opt1.swap(opt2);
+        assert(X::dtor_called == 1);
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 2);
+        assert(static_cast<bool>(opt2) == false);
+    }
+    {
+        optional<X> opt1(1);
+        optional<X> opt2(2);
+        static_assert(noexcept(opt1.swap(opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        X::dtor_called = 0;
+        opt1.swap(opt2);
+        assert(X::dtor_called == 1);  // from inside std::swap
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 2);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 1);
+    }
+    {
+        optional<Y> opt1;
+        optional<Y> opt2;
+        static_assert(noexcept(opt1.swap(opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+        opt1.swap(opt2);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+        assert(Y::dtor_called == 0);
+    }
+    {
+        optional<Y> opt1(1);
+        optional<Y> opt2;
+        static_assert(noexcept(opt1.swap(opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == false);
+        Y::dtor_called = 0;
+        opt1.swap(opt2);
+        assert(Y::dtor_called == 1);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 1);
+    }
+    {
+        optional<Y> opt1;
+        optional<Y> opt2(2);
+        static_assert(noexcept(opt1.swap(opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        Y::dtor_called = 0;
+        opt1.swap(opt2);
+        assert(Y::dtor_called == 1);
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 2);
+        assert(static_cast<bool>(opt2) == false);
+    }
+    {
+        optional<Y> opt1(1);
+        optional<Y> opt2(2);
+        static_assert(noexcept(opt1.swap(opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        Y::dtor_called = 0;
+        opt1.swap(opt2);
+        assert(Y::dtor_called == 0);
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 2);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 1);
+    }
+    {
+        optional<Z> opt1;
+        optional<Z> opt2;
+        static_assert(noexcept(opt1.swap(opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+        opt1.swap(opt2);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+    }
+    {
+        optional<Z> opt1;
+        opt1.emplace(1);
+        optional<Z> opt2;
+        static_assert(noexcept(opt1.swap(opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == false);
+        try
+        {
+            opt1.swap(opt2);
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 7);
+        }
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == false);
+    }
+    {
+        optional<Z> opt1;
+        optional<Z> opt2;
+        opt2.emplace(2);
+        static_assert(noexcept(opt1.swap(opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        try
+        {
+            opt1.swap(opt2);
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 7);
+        }
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+    }
+    {
+        optional<Z> opt1;
+        opt1.emplace(1);
+        optional<Z> opt2;
+        opt2.emplace(2);
+        static_assert(noexcept(opt1.swap(opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        try
+        {
+            opt1.swap(opt2);
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 6);
+        }
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+    }
+}

test/std/utilities/optional/optional.object/optional_const_void.fail.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// T shall be an object type and shall satisfy the requirements of Destructible
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+
+    optional<const void> opt;
+}

test/std/utilities/optional/optional.object/optional_not_destructible.fail.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// T shall be an object type and shall satisfy the requirements of Destructible
+
+#include <optional>
+
+using std::optional;
+
+struct X
+{
+private:
+    ~X() {}
+};
+
+int main()
+{
+    optional<X> opt;
+}

test/std/utilities/optional/optional.object/optional_not_noexcept_destructible.fail.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// T shall be an object type and shall satisfy the requirements of Destructible
+
+#include <optional>
+
+using std::optional;
+
+struct X
+{
+    ~X() noexcept(false) {}
+};
+
+int main()
+{
+    optional<X> opt;
+}

test/std/utilities/optional/optional.object/optional_void.fail.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// T shall be an object type and shall satisfy the requirements of Destructible
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+
+    optional<void> opt;
+}

test/std/utilities/optional/optional.object/types.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T>
+// class optional
+// {
+// public:
+//     typedef T value_type;
+//     ...
+
+#include <optional>
+#include <type_traits>
+
+using std::optional;
+
+template <class Opt, class T>
+void
+test()
+{
+    static_assert(std::is_same<typename Opt::value_type, T>::value, "");
+}
+
+int main()
+{
+    test<optional<int>, int>();
+    test<optional<const int>, const int>();
+    test<optional<double>, double>();
+    test<optional<const double>, const double>();
+}

test/std/utilities/optional/optional.relops/equal.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator==(const optional<T>& x, const optional<T>& y);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    int i_;
+
+    constexpr X(int i) : i_(i) {}
+};
+
+constexpr bool operator == ( const X &lhs, const X &rhs )
+    { return lhs.i_ == rhs.i_ ; }
+
+int main()
+{
+    {
+    typedef X T;
+    typedef optional<T> O;
+
+    constexpr O o1;     // disengaged
+    constexpr O o2;     // disengaged
+    constexpr O o3{1};  // engaged
+    constexpr O o4{2};  // engaged
+    constexpr O o5{1};  // engaged
+
+    static_assert (   o1 == o1 , "" );
+    static_assert (   o1 == o2 , "" );
+    static_assert ( !(o1 == o3), "" );
+    static_assert ( !(o1 == o4), "" );
+    static_assert ( !(o1 == o5), "" );
+
+    static_assert (   o2 == o1 , "" );
+    static_assert (   o2 == o2 , "" );
+    static_assert ( !(o2 == o3), "" );
+    static_assert ( !(o2 == o4), "" );
+    static_assert ( !(o2 == o5), "" );
+
+    static_assert ( !(o3 == o1), "" );
+    static_assert ( !(o3 == o2), "" );
+    static_assert (   o3 == o3 , "" );
+    static_assert ( !(o3 == o4), "" );
+    static_assert (   o3 == o5 , "" );
+
+    static_assert ( !(o4 == o1), "" );
+    static_assert ( !(o4 == o2), "" );
+    static_assert ( !(o4 == o3), "" );
+    static_assert (   o4 == o4 , "" );
+    static_assert ( !(o4 == o5), "" );
+
+    static_assert ( !(o5 == o1), "" );
+    static_assert ( !(o5 == o2), "" );
+    static_assert (   o5 == o3 , "" );
+    static_assert ( !(o5 == o4), "" );
+    static_assert (   o5 == o5 , "" );
+
+    }
+}

test/std/utilities/optional/optional.relops/greater_equal.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator>= (const optional<T>& x, const optional<T>& y);
+
+#include <optional>
+
+using std::optional;
+
+struct X
+{
+    int i_;
+
+    constexpr X(int i) : i_(i) {}
+};
+
+constexpr bool operator >= ( const X &lhs, const X &rhs )
+    { return lhs.i_ >= rhs.i_ ; }
+
+int main()
+{
+    {
+    typedef optional<X> O;
+
+    constexpr O o1;     // disengaged
+    constexpr O o2;     // disengaged
+    constexpr O o3{1};  // engaged
+    constexpr O o4{2};  // engaged
+    constexpr O o5{1};  // engaged
+
+    static_assert (  (o1 >= o1), "" );
+    static_assert (  (o1 >= o2), "" );
+    static_assert ( !(o1 >= o3), "" );
+    static_assert ( !(o1 >= o4), "" );
+    static_assert ( !(o1 >= o5), "" );
+
+    static_assert (  (o2 >= o1), "" );
+    static_assert (  (o2 >= o2), "" );
+    static_assert ( !(o2 >= o3), "" );
+    static_assert ( !(o2 >= o4), "" );
+    static_assert ( !(o2 >= o5), "" );
+
+    static_assert (  (o3 >= o1), "" );
+    static_assert (  (o3 >= o2), "" );
+    static_assert (  (o3 >= o3), "" );
+    static_assert ( !(o3 >= o4), "" );
+    static_assert (  (o3 >= o5), "" );
+
+    static_assert (  (o4 >= o1), "" );
+    static_assert (  (o4 >= o2), "" );
+    static_assert (  (o4 >= o3), "" );
+    static_assert (  (o4 >= o4), "" );
+    static_assert (  (o4 >= o5), "" );
+
+    static_assert (  (o5 >= o1), "" );
+    static_assert (  (o5 >= o2), "" );
+    static_assert (  (o5 >= o3), "" );
+    static_assert ( !(o5 >= o4), "" );
+    static_assert (  (o5 >= o5), "" );
+    }
+}

test/std/utilities/optional/optional.relops/greater_than.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator> (const optional<T>& x, const optional<T>& y);
+
+#include <optional>
+
+using std::optional;
+
+struct X
+{
+    int i_;
+
+    constexpr X(int i) : i_(i) {}
+};
+
+constexpr bool operator > ( const X &lhs, const X &rhs )
+    { return lhs.i_ > rhs.i_ ; }
+
+int main()
+{
+    {
+    typedef optional<X> O;
+
+    constexpr O o1;     // disengaged
+    constexpr O o2;     // disengaged
+    constexpr O o3{1};  // engaged
+    constexpr O o4{2};  // engaged
+    constexpr O o5{1};  // engaged
+
+    static_assert ( !(o1 > o1), "" );
+    static_assert ( !(o1 > o2), "" );
+    static_assert ( !(o1 > o3), "" );
+    static_assert ( !(o1 > o4), "" );
+    static_assert ( !(o1 > o5), "" );
+
+    static_assert ( !(o2 > o1), "" );
+    static_assert ( !(o2 > o2), "" );
+    static_assert ( !(o2 > o3), "" );
+    static_assert ( !(o2 > o4), "" );
+    static_assert ( !(o2 > o5), "" );
+
+    static_assert (  (o3 > o1), "" );
+    static_assert (  (o3 > o2), "" );
+    static_assert ( !(o3 > o3), "" );
+    static_assert ( !(o3 > o4), "" );
+    static_assert ( !(o3 > o5), "" );
+
+    static_assert (  (o4 > o1), "" );
+    static_assert (  (o4 > o2), "" );
+    static_assert (  (o4 > o3), "" );
+    static_assert ( !(o4 > o4), "" );
+    static_assert (  (o4 > o5), "" );
+
+    static_assert (  (o5 > o1), "" );
+    static_assert (  (o5 > o2), "" );
+    static_assert ( !(o5 > o3), "" );
+    static_assert ( !(o5 > o4), "" );
+    static_assert ( !(o5 > o5), "" );
+    }
+}

test/std/utilities/optional/optional.relops/less_equal.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator<= (const optional<T>& x, const optional<T>& y);
+
+#include <optional>
+
+using std::optional;
+
+struct X
+{
+    int i_;
+
+    constexpr X(int i) : i_(i) {}
+};
+
+constexpr bool operator <= ( const X &lhs, const X &rhs )
+    { return lhs.i_ <= rhs.i_ ; }
+
+int main()
+{
+    {
+    typedef optional<X> O;
+
+    constexpr O o1;     // disengaged
+    constexpr O o2;     // disengaged
+    constexpr O o3{1};  // engaged
+    constexpr O o4{2};  // engaged
+    constexpr O o5{1};  // engaged
+
+    static_assert (  (o1 <= o1), "" );
+    static_assert (  (o1 <= o2), "" );
+    static_assert (  (o1 <= o3), "" );
+    static_assert (  (o1 <= o4), "" );
+    static_assert (  (o1 <= o5), "" );
+
+    static_assert (  (o2 <= o1), "" );
+    static_assert (  (o2 <= o2), "" );
+    static_assert (  (o2 <= o3), "" );
+    static_assert (  (o2 <= o4), "" );
+    static_assert (  (o2 <= o5), "" );
+
+    static_assert ( !(o3 <= o1), "" );
+    static_assert ( !(o3 <= o2), "" );
+    static_assert (  (o3 <= o3), "" );
+    static_assert (  (o3 <= o4), "" );
+    static_assert (  (o3 <= o5), "" );
+
+    static_assert ( !(o4 <= o1), "" );
+    static_assert ( !(o4 <= o2), "" );
+    static_assert ( !(o4 <= o3), "" );
+    static_assert (  (o4 <= o4), "" );
+    static_assert ( !(o4 <= o5), "" );
+
+    static_assert ( !(o5 <= o1), "" );
+    static_assert ( !(o5 <= o2), "" );
+    static_assert (  (o5 <= o3), "" );
+    static_assert (  (o5 <= o4), "" );
+    static_assert (  (o5 <= o5), "" );
+    }
+}

test/std/utilities/optional/optional.relops/less_than.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator< (const optional<T>& x, const optional<T>& y);
+
+#include <optional>
+
+using std::optional;
+
+struct X
+{
+    int i_;
+
+    constexpr X(int i) : i_(i) {}
+};
+
+constexpr bool operator < ( const X &lhs, const X &rhs )
+    { return lhs.i_ < rhs.i_ ; }
+
+int main()
+{
+    {
+    typedef optional<X> O;
+
+    constexpr O o1;     // disengaged
+    constexpr O o2;     // disengaged
+    constexpr O o3{1};  // engaged
+    constexpr O o4{2};  // engaged
+    constexpr O o5{1};  // engaged
+
+    static_assert ( !(o1 < o1), "" );
+    static_assert ( !(o1 < o2), "" );
+    static_assert (  (o1 < o3), "" );
+    static_assert (  (o1 < o4), "" );
+    static_assert (  (o1 < o5), "" );
+
+    static_assert ( !(o2 < o1), "" );
+    static_assert ( !(o2 < o2), "" );
+    static_assert (  (o2 < o3), "" );
+    static_assert (  (o2 < o4), "" );
+    static_assert (  (o2 < o5), "" );
+
+    static_assert ( !(o3 < o1), "" );
+    static_assert ( !(o3 < o2), "" );
+    static_assert ( !(o3 < o3), "" );
+    static_assert (  (o3 < o4), "" );
+    static_assert ( !(o3 < o5), "" );
+
+    static_assert ( !(o4 < o1), "" );
+    static_assert ( !(o4 < o2), "" );
+    static_assert ( !(o4 < o3), "" );
+    static_assert ( !(o4 < o4), "" );
+    static_assert ( !(o4 < o5), "" );
+
+    static_assert ( !(o5 < o1), "" );
+    static_assert ( !(o5 < o2), "" );
+    static_assert ( !(o5 < o3), "" );
+    static_assert (  (o5 < o4), "" );
+    static_assert ( !(o5 < o5), "" );
+    }
+}

test/std/utilities/optional/optional.relops/not_equal.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator!=(const optional<T>& x, const optional<T>& y);
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    int i_;
+
+    constexpr X(int i) : i_(i) {}
+};
+
+constexpr bool operator != ( const X &lhs, const X &rhs )
+    { return lhs.i_ != rhs.i_ ; }
+
+int main()
+{
+    {
+    typedef X T;
+    typedef optional<T> O;
+
+    constexpr O o1;     // disengaged
+    constexpr O o2;     // disengaged
+    constexpr O o3{1};  // engaged
+    constexpr O o4{2};  // engaged
+    constexpr O o5{1};  // engaged
+
+    static_assert ( !(o1 != o1), "" );
+    static_assert ( !(o1 != o2), "" );
+    static_assert (  (o1 != o3), "" );
+    static_assert (  (o1 != o4), "" );
+    static_assert (  (o1 != o5), "" );
+
+    static_assert ( !(o2 != o1), "" );
+    static_assert ( !(o2 != o2), "" );
+    static_assert (  (o2 != o3), "" );
+    static_assert (  (o2 != o4), "" );
+    static_assert (  (o2 != o5), "" );
+
+    static_assert (  (o3 != o1), "" );
+    static_assert (  (o3 != o2), "" );
+    static_assert ( !(o3 != o3), "" );
+    static_assert (  (o3 != o4), "" );
+    static_assert ( !(o3 != o5), "" );
+
+    static_assert (  (o4 != o1), "" );
+    static_assert (  (o4 != o2), "" );
+    static_assert (  (o4 != o3), "" );
+    static_assert ( !(o4 != o4), "" );
+    static_assert (  (o4 != o5), "" );
+
+    static_assert (  (o5 != o1), "" );
+    static_assert (  (o5 != o2), "" );
+    static_assert ( !(o5 != o3), "" );
+    static_assert (  (o5 != o4), "" );
+    static_assert ( !(o5 != o5), "" );
+
+    }
+}

test/std/utilities/optional/optional.specalg/make_optional.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T>
+//   constexpr optional<decay_t<T>> make_optional(T&& v);
+
+#include <optional>
+#include <string>
+#include <memory>
+#include <cassert>
+
+int main()
+{
+    using std::optional;
+    using std::make_optional;
+
+    {
+        optional<int> opt = make_optional(2);
+        assert(*opt == 2);
+    }
+    {
+        std::string s("123");
+        optional<std::string> opt = make_optional(s);
+        assert(*opt == s);
+    }
+    {
+        std::unique_ptr<int> s(new int(3));
+        optional<std::unique_ptr<int>> opt = make_optional(std::move(s));
+        assert(**opt == 3);
+        assert(s == nullptr);
+    }
+}

test/std/utilities/optional/optional.specalg/make_optional_explicit.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T, class... Args>
+//   constexpr optional<T> make_optional(Args&&... args);
+
+#include <optional>
+#include <string>
+#include <memory>
+#include <cassert>
+
+int main()
+{
+    using std::optional;
+    using std::make_optional;
+
+    {
+        auto opt = make_optional<int>(2);
+        assert(*opt == 2);
+    }
+    {
+        std::string s("123");
+        auto opt = make_optional<std::string>(s);
+        assert(*opt == s);
+    }
+    {
+        std::unique_ptr<int> s(new int(3));
+        auto opt = make_optional<std::unique_ptr<int>>(std::move(s));
+        assert(**opt == 3);
+        assert(s == nullptr);
+    }
+    {
+        auto opt = make_optional<std::string>(4, 'X');
+        assert(*opt == "XXXX");
+    }
+}

test/std/utilities/optional/optional.specalg/make_optional_explicit_initializer_list.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T, class U, class... Args>
+//   constexpr optional<T> make_optional(initializer_list<U> il, Args&&... args);
+
+#include <optional>
+#include <string>
+#include <memory>
+#include <cassert>
+
+int main()
+{
+    using std::make_optional;
+
+    {
+        auto opt = make_optional<std::string>({'1', '2', '3'});
+        assert(*opt == "123");
+    }
+    {
+        auto opt = make_optional<std::string>({'a', 'b', 'c'}, std::allocator<char>{});
+        assert(*opt == "abc");
+    }
+}

test/std/utilities/optional/optional.specalg/swap.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> void swap(optional<T>& x, optional<T>& y)
+//     noexcept(noexcept(x.swap(y)));
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+class X
+{
+    int i_;
+public:
+    static unsigned dtor_called;
+    X(int i) : i_(i) {}
+    X(X&& x) = default;
+    X& operator=(X&&) = default;
+    ~X() {++dtor_called;}
+
+    friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
+};
+
+unsigned X::dtor_called = 0;
+
+class Y
+{
+    int i_;
+public:
+    static unsigned dtor_called;
+    Y(int i) : i_(i) {}
+    Y(Y&&) = default;
+    ~Y() {++dtor_called;}
+
+    friend constexpr bool operator==(const Y& x, const Y& y) {return x.i_ == y.i_;}
+    friend void swap(Y& x, Y& y) {std::swap(x.i_, y.i_);}
+};
+
+unsigned Y::dtor_called = 0;
+
+class Z
+{
+    int i_;
+public:
+    Z(int i) : i_(i) {}
+    Z(Z&&) {throw 7;}
+
+    friend constexpr bool operator==(const Z& x, const Z& y) {return x.i_ == y.i_;}
+    friend void swap(Z& x, Z& y) {throw 6;}
+};
+
+int main()
+{
+    {
+        optional<int> opt1;
+        optional<int> opt2;
+        static_assert(noexcept(swap(opt1, opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+        swap(opt1, opt2);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+    }
+    {
+        optional<int> opt1(1);
+        optional<int> opt2;
+        static_assert(noexcept(swap(opt1, opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == false);
+        swap(opt1, opt2);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 1);
+    }
+    {
+        optional<int> opt1;
+        optional<int> opt2(2);
+        static_assert(noexcept(swap(opt1, opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        swap(opt1, opt2);
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 2);
+        assert(static_cast<bool>(opt2) == false);
+    }
+    {
+        optional<int> opt1(1);
+        optional<int> opt2(2);
+        static_assert(noexcept(swap(opt1, opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        swap(opt1, opt2);
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 2);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 1);
+    }
+    {
+        optional<X> opt1;
+        optional<X> opt2;
+        static_assert(noexcept(swap(opt1, opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+        swap(opt1, opt2);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+        assert(X::dtor_called == 0);
+    }
+    {
+        optional<X> opt1(1);
+        optional<X> opt2;
+        static_assert(noexcept(swap(opt1, opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == false);
+        X::dtor_called = 0;
+        swap(opt1, opt2);
+        assert(X::dtor_called == 1);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 1);
+    }
+    {
+        optional<X> opt1;
+        optional<X> opt2(2);
+        static_assert(noexcept(swap(opt1, opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        X::dtor_called = 0;
+        swap(opt1, opt2);
+        assert(X::dtor_called == 1);
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 2);
+        assert(static_cast<bool>(opt2) == false);
+    }
+    {
+        optional<X> opt1(1);
+        optional<X> opt2(2);
+        static_assert(noexcept(swap(opt1, opt2)) == true, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        X::dtor_called = 0;
+        swap(opt1, opt2);
+        assert(X::dtor_called == 1);  // from inside std::swap
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 2);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 1);
+    }
+    {
+        optional<Y> opt1;
+        optional<Y> opt2;
+        static_assert(noexcept(swap(opt1, opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+        swap(opt1, opt2);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+        assert(Y::dtor_called == 0);
+    }
+    {
+        optional<Y> opt1(1);
+        optional<Y> opt2;
+        static_assert(noexcept(swap(opt1, opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == false);
+        Y::dtor_called = 0;
+        swap(opt1, opt2);
+        assert(Y::dtor_called == 1);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 1);
+    }
+    {
+        optional<Y> opt1;
+        optional<Y> opt2(2);
+        static_assert(noexcept(swap(opt1, opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        Y::dtor_called = 0;
+        swap(opt1, opt2);
+        assert(Y::dtor_called == 1);
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 2);
+        assert(static_cast<bool>(opt2) == false);
+    }
+    {
+        optional<Y> opt1(1);
+        optional<Y> opt2(2);
+        static_assert(noexcept(swap(opt1, opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        Y::dtor_called = 0;
+        swap(opt1, opt2);
+        assert(Y::dtor_called == 0);
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 2);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 1);
+    }
+    {
+        optional<Z> opt1;
+        optional<Z> opt2;
+        static_assert(noexcept(swap(opt1, opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+        swap(opt1, opt2);
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == false);
+    }
+    {
+        optional<Z> opt1;
+        opt1.emplace(1);
+        optional<Z> opt2;
+        static_assert(noexcept(swap(opt1, opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == false);
+        try
+        {
+            swap(opt1, opt2);
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 7);
+        }
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == false);
+    }
+    {
+        optional<Z> opt1;
+        optional<Z> opt2;
+        opt2.emplace(2);
+        static_assert(noexcept(swap(opt1, opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        try
+        {
+            swap(opt1, opt2);
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 7);
+        }
+        assert(static_cast<bool>(opt1) == false);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+    }
+    {
+        optional<Z> opt1;
+        opt1.emplace(1);
+        optional<Z> opt2;
+        opt2.emplace(2);
+        static_assert(noexcept(swap(opt1, opt2)) == false, "");
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+        try
+        {
+            swap(opt1, opt2);
+            assert(false);
+        }
+        catch (int i)
+        {
+            assert(i == 6);
+        }
+        assert(static_cast<bool>(opt1) == true);
+        assert(*opt1 == 1);
+        assert(static_cast<bool>(opt2) == true);
+        assert(*opt2 == 2);
+    }
+}

test/std/utilities/optional/optional.syn/optional_const_in_place_t.fail.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// A program that necessitates the instantiation of template optional for
+// (possibly cv-qualified) in_place_t is ill-formed.
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+    using std::in_place_t;
+    using std::in_place;
+
+    optional<const in_place_t> opt;
+}

test/std/utilities/optional/optional.syn/optional_const_lvalue_ref.fail.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// A program that necessitates the instantiation of template optional for a
+// reference type is ill-formed.
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+
+    optional<const int&> opt;
+}

test/std/utilities/optional/optional.syn/optional_const_nullopt_t.fail.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// A program that necessitates the instantiation of template optional for
+// (possibly cv-qualified) nullopt_t is ill-formed.
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+    using std::nullopt_t;
+    using std::nullopt;
+
+    optional<const nullopt_t> opt;
+}

test/std/utilities/optional/optional.syn/optional_in_place_t.fail.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// A program that necessitates the instantiation of template optional for
+// (possibly cv-qualified) in_place_t is ill-formed.
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+    using std::in_place_t;
+    using std::in_place;
+
+    optional<in_place_t> opt;
+}

test/std/utilities/optional/optional.syn/optional_includes_initializer_list.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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 <initializer_list>
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+
+    std::initializer_list<int> list;
+}

test/std/utilities/optional/optional.syn/optional_lvalue_ref.fail.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// A program that necessitates the instantiation of template optional for a
+// reference type is ill-formed.
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+
+    optional<int&> opt;
+}

test/std/utilities/optional/optional.syn/optional_nullopt_t.fail.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// A program that necessitates the instantiation of template optional for
+// (possibly cv-qualified) nullopt_t is ill-formed.
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+    using std::nullopt_t;
+    using std::nullopt;
+
+    optional<nullopt_t> opt;
+}

test/std/utilities/optional/optional.syn/optional_rvalue_ref.fail.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// A program that necessitates the instantiation of template optional for a
+// reference type is ill-formed.
+
+#include <optional>
+
+int main()
+{
+    using std::optional;
+
+    optional<int&&> opt;
+}