Import libc++ trunk r224926. This fixes a number of bugs, completes

C++14 support[1], adds more C++1z features[2], and fixes the following
LWG issues[3]:

1450: Contradiction in regex_constants
2003: String exception inconsistency in erase.
2075: Progress guarantees, lock-free property, and scheduling
      assumptions
2104: unique_lock move-assignment should not be noexcept
2112: User-defined classes that cannot be derived from
2132: std::function ambiguity
2135: Unclear requirement for exceptions thrown in
      condition_variable::wait()
2142: packaged_task::operator() synchronization too broad?
2182: Container::[const_]reference types are misleadingly specified
2186: Incomplete action on async/launch::deferred
2188: Reverse iterator does not fully support targets that overload
      operator&
2193: Default constructors for standard library containers are explicit
2205: Problematic postconditions of regex_match and regex_search
2213: Return value of std::regex_replace
2240: Probable misuse of term "function scope" in [thread.condition]
2252: Strong guarantee on vector::push_back() still broken with C++11?
2257: Simplify container requirements with the new algorithms
2258: a.erase(q1, q2) unable to directly return q2
2263: Comparing iterators and allocator pointers with different
      const-character
2268: Setting a default argument in the declaration of a member
      function assign of std::basic_string
2271: regex_traits::lookup_classname specification unclear
2272: quoted should use char_traits::eq for character comparison
2278: User-defined literals for Standard Library types
2280: begin / end for arrays should be constexpr and noexcept
2285: make_reverse_iterator
2288: Inconsistent requirements for shared mutexes
2291: std::hash is vulnerable to collision DoS attack
2293: Wrong facet used by num_put::do_put
2299: Effects of inaccessible key_compare::is_transparent type are not
      clear
2301: Why is std::tie not constexpr?
2304: Complexity of count in unordered associative containers
2306: match_results::reference should be value_type&, not const
      value_type&
2308: Clarify container destructor requirements w.r.t. std::array
2313: tuple_size should always derive from integral_constant<size_t, N>
2314: apply() should return decltype(auto) and use decay_t before
      tuple_size
2315: weak_ptr should be movable
2316: weak_ptr::lock() should be atomic
2317: The type property queries should be UnaryTypeTraits returning
      size_t
2320: select_on_container_copy_construction() takes allocators, not
      containers
2322: Associative(initializer_list, stuff) constructors are
      underspecified
2323: vector::resize(n, t)'s specification should be simplified
2324: Insert iterator constructors should use addressof()
2329: regex_match()/regex_search() with match_results should forbid
      temporary strings
2330: regex("meow", regex::icase) is technically forbidden but should
      be permitted
2332: regex_iterator/regex_token_iterator should forbid temporary
      regexes
2339: Wording issue in nth_element
2341: Inconsistency between basic_ostream::seekp(pos) and
      basic_ostream::seekp(off, dir)
2344: quoted()'s interaction with padding is unclear
2346: integral_constant's member functions should be marked noexcept
2350: min, max, and minmax should be constexpr
2356: Stability of erasure in unordered associative containers
2357: Remaining "Assignable" requirement
2359: How does regex_constants::nosubs affect basic_regex::mark_count()?
2360: reverse_iterator::operator*() is unimplementable

[1] http://libcxx.llvm.org/cxx1y_status.html
[2] http://libcxx.llvm.org/cxx1z_status.html
[3] http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html

Exp-run:	antoine
MFC after:	1 month

6 files changed, 1642 insertions, 141 deletions

diff --git a/contrib/libc++/include/experimental/__config b/contrib/libc++/include/experimental/__config
new file mode 100644
index 0000000..684a3b4
--- /dev/null
+++ b/contrib/libc++/include/experimental/__config
@@ -0,0 +1,24 @@
+// -*- C++ -*-
+//===--------------------------- __config ---------------------------------===//
+//
+//                     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_EXPERIMENTAL_CONFIG
+#define _LIBCPP_EXPERIMENTAL_CONFIG
+
+#include <__config>
+
+#define _LIBCPP_BEGIN_NAMESPACE_EXPERIMENTAL namespace std { namespace experimental {
+#define _LIBCPP_END_NAMESPACE_EXPERIMENTAL  } }
+#define _VSTD_EXPERIMENTAL std::experimental
+
+#define _LIBCPP_BEGIN_NAMESPACE_LFTS _LIBCPP_BEGIN_NAMESPACE_EXPERIMENTAL inline namespace fundamentals_v1 {
+#define _LIBCPP_END_NAMESPACE_LFTS  } } }
+#define _VSTD_LFTS _VSTD_EXPERIMENTAL::fundamentals_v1
+
+#endif
diff --git a/contrib/libc++/include/experimental/dynarray b/contrib/libc++/include/experimental/dynarray
index 7c5c9b3..0bc8dfe 100644
--- a/contrib/libc++/include/experimental/dynarray
+++ b/contrib/libc++/include/experimental/dynarray
@@ -38,18 +38,18 @@ class dynarray
 public:
     // construct/copy/destroy:
     explicit dynarray(size_type c);
-    template <typename Alloc>
-      dynarray(size_type c, const Alloc& alloc);
     dynarray(size_type c, const T& v);
-    template <typename Alloc>
-      dynarray(size_type c, const T& v, const Alloc& alloc);
     dynarray(const dynarray& d);
-    template <typename Alloc>
-      dynarray(const dynarray& d, const Alloc& alloc);
     dynarray(initializer_list<T>);
-    template <typename Alloc>
-      dynarray(initializer_list<T>, const Alloc& alloc);
 
+    template <class Alloc>
+      dynarray(allocator_arg_t, const Alloc& a, size_type c, const Alloc& alloc);
+    template <class Alloc>
+      dynarray(allocator_arg_t, const Alloc& a, size_type c, const T& v, const Alloc& alloc);
+    template <class Alloc>
+      dynarray(allocator_arg_t, const Alloc& a, const dynarray& d, const Alloc& alloc);
+    template <class Alloc>
+      dynarray(allocator_arg_t, const Alloc& a, initializer_list<T>, const Alloc& alloc);
     dynarray& operator=(const dynarray&) = delete;
     ~dynarray();
 
@@ -147,12 +147,12 @@ private:
             assert(!"dynarray::allocation");
 #endif
         }
-        return static_cast<value_type *> (::operator new (sizeof(value_type) * count));
+        return static_cast<value_type *> (_VSTD::__allocate (sizeof(value_type) * count));
     }
 
     static inline _LIBCPP_INLINE_VISIBILITY void __deallocate ( value_type* __ptr ) noexcept
     {
-        ::operator delete (static_cast<void *> (__ptr));
+        _VSTD::__deallocate (static_cast<void *> (__ptr));
     }
 
 public:
@@ -163,15 +163,15 @@ public:
     dynarray(initializer_list<value_type>);
 
 //  We're not implementing these right now.
-//  Waiting for the resolution of LWG issue #2235
+//  Updated with the resolution of LWG issue #2255
 //     template <typename _Alloc>
-//       dynarray(size_type __c, const _Alloc& __alloc);
+//       dynarray(allocator_arg_t, const _Alloc& __alloc, size_type __c);
 //     template <typename _Alloc>
-//       dynarray(size_type __c, const value_type& __v, const _Alloc& __alloc);
+//       dynarray(allocator_arg_t, const _Alloc& __alloc, size_type __c, const value_type& __v);
 //     template <typename _Alloc>
-//       dynarray(const dynarray& __d, const _Alloc& __alloc);
+//       dynarray(allocator_arg_t, const _Alloc& __alloc, const dynarray& __d);
 //     template <typename _Alloc>
-//       dynarray(initializer_list<value_type>, const _Alloc& __alloc);
+//       dynarray(allocator_arg_t, const _Alloc& __alloc, initializer_list<value_type>);
 
     dynarray& operator=(const dynarray&) = delete;
     ~dynarray();
diff --git a/contrib/libc++/include/experimental/optional b/contrib/libc++/include/experimental/optional
index 3848da8..a384882 100644
--- a/contrib/libc++/include/experimental/optional
+++ b/contrib/libc++/include/experimental/optional
@@ -16,131 +16,147 @@
 
 // C++1y
 
-#include <initializer_list>
-
-namespace std { namespace experimental {
-
-// optional for object types
-template <class T>
-class optional
-{
-public:
-    typedef T value_type;
-
-    // constructors
-    constexpr optional() noexcept;
-    constexpr optional(nullopt_t) noexcept;
-    optional(const optional&);
-    optional(optional&&) noexcept(is_nothrow_move_constructible<T>::value);
-    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&&...);
-
-    // destructor
-    ~optional();
-
-    // assignment
-    optional& operator=(nullopt_t) noexcept;
-    optional& operator=(const optional&);
-    optional& operator=(optional&&)
-        noexcept(is_nothrow_move_assignable<T>::value &&
-                 is_nothrow_move_constructible<T>::value);
-    template <class U> optional& operator=(U&&);
-    template <class... Args> void emplace(Args&&...);
-    template <class U, class... Args> void emplace(initializer_list<U>, Args&&...);
-
-    // swap
-    void swap(optional&)
-        noexcept(is_nothrow_move_constructible<T>::value &&
-                 noexcept(swap(declval<T&>(), declval<T&>())));
-
-    // observers
-    constexpr T const* operator->() const;
-    T* operator->();
-    constexpr T const& operator*() const;
-    T& operator*();
-    constexpr explicit operator bool() const noexcept;
-    constexpr T const& value() const;
-    T& value();
-    template <class U> constexpr T value_or(U&&) const&;
-    template <class U> T value_or(U&&) &&;
-};
-
-// In-place construction
-struct in_place_t{};
-constexpr in_place_t in_place{};
-
-// Disengaged state indicator
-struct nullopt_t{see below};
-constexpr nullopt_t nullopt(unspecified);
-
-// class bad_optional_access
-class bad_optional_access
-    : public logic_error
-{
-public:
-    explicit bad_optional_access(const string& what_arg);
-    explicit bad_optional_access(const char* what_arg);
-};
-
-// 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>&);
-
-// Comparison with nullopt
-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;
-
-// 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>&);
-
-// Specialized algorithms
-template <class T> void swap(optional<T>&, optional<T>&) noexcept(see below);
-template <class T> constexpr optional<typename decay<T>::type> make_optional(T&&);
-
-// hash support
-template <class T> struct hash;
-template <class T> struct hash<optional<T>>;
-
-}}  // std::experimental
+namespace std { namespace experimental { inline namespace fundamentals_v1 {
+
+    // 5.3, optional for object types
+    template <class T> class optional;
+
+    // 5.4, In-place construction
+    struct in_place_t{};
+    constexpr in_place_t in_place{};
+
+    // 5.5, No-value state indicator
+    struct nullopt_t{see below};
+    constexpr nullopt_t nullopt(unspecified);
+
+    // 5.6, Class bad_optional_access
+    class bad_optional_access;
+
+    // 5.7, 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>&);
+
+    // 5.8, Comparison with nullopt
+    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;
+
+    // 5.9, 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>&);
+
+    // 5.10, 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 optional
+	{
+	public:
+	  typedef T value_type;
+
+	  // 5.3.1, 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&&...);
+
+	  // 5.3.2, Destructor
+	  ~optional();
+
+	  // 5.3.3, 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&&...);
+
+	  // 5.3.4, Swap
+	  void swap(optional&) noexcept(see below);
+
+	  // 5.3.5, 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 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&&) &&;
+
+	private:
+	  T*   val;  // exposition only
+	};
+
+  } // namespace fundamentals_v1
+  } // namespace experimental
+
+  // 5.11, Hash support
+  template <class T> struct hash;
+  template <class T> struct hash<experimental::optional<T>>;
+
+} // namespace std
 
 */
 
-#include <__config>
+#include <experimental/__config>
 #include <functional>
 #include <stdexcept>
 
-namespace std { namespace experimental {
-
+_LIBCPP_BEGIN_NAMESPACE_EXPERIMENTAL
 class _LIBCPP_EXCEPTION_ABI bad_optional_access
-    : public logic_error
+    : public std::logic_error
 {
 public:
-#if _LIBCPP_STD_VER > 11
-    _LIBCPP_INLINE_VISIBILITY explicit bad_optional_access(const string& __arg)
-        : logic_error(__arg) {}
-    _LIBCPP_INLINE_VISIBILITY explicit bad_optional_access(const char* __arg)
-        : logic_error(__arg) {}
-    _LIBCPP_INLINE_VISIBILITY bad_optional_access(const bad_optional_access&) noexcept = default;
-    _LIBCPP_INLINE_VISIBILITY bad_optional_access& operator=(const bad_optional_access&) noexcept = default;
-#else
-private:
-    bad_optional_access(const bad_optional_access&);
-    bad_optional_access& operator=(const bad_optional_access&);
-public:
-#endif  // _LIBCPP_STD_VER > 11
-    // Get the key function ~bad_optional_access() into the dylib even if not compiling for C++1y
+	bad_optional_access() : std::logic_error("Bad optional Access") {}
+
+//	Get the key function ~bad_optional_access() into the dylib
     virtual ~bad_optional_access() _NOEXCEPT;
 };
 
-}}  // std::experimental
+_LIBCPP_END_NAMESPACE_EXPERIMENTAL
+
 
 #if _LIBCPP_STD_VER > 11
 
@@ -148,20 +164,14 @@ public:
 #include <type_traits>
 #include <new>
 #include <__functional_base>
-
 #include <__undef_min_max>
-
-#ifdef _LIBCPP_DEBUG
-#   include <__debug>
-#else
-#   define _LIBCPP_ASSERT(x, m) ((void)0)
-#endif
+#include <__debug>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
-namespace std { namespace experimental { inline namespace __library_fundamentals_v1 {
+_LIBCPP_BEGIN_NAMESPACE_LFTS
 
 struct in_place_t {};
 constexpr in_place_t in_place{};
@@ -507,7 +517,7 @@ public:
     constexpr value_type const& value() const
     {
         if (!this->__engaged_)
-            throw bad_optional_access("optional<T>::value: not engaged");
+            throw bad_optional_access();
         return this->__val_;
     }
 
@@ -515,7 +525,7 @@ public:
     value_type& value()
     {
         if (!this->__engaged_)
-            throw bad_optional_access("optional<T>::value: not engaged");
+            throw bad_optional_access();
         return this->__val_;
     }
 
@@ -560,6 +570,7 @@ private:
     }
 };
 
+// Comparisons between optionals
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
 constexpr
@@ -577,19 +588,57 @@ template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
 constexpr
 bool
+operator!=(const optional<_Tp>& __x, const optional<_Tp>& __y)
+{
+    return !(__x == __y);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
 operator<(const optional<_Tp>& __x, const optional<_Tp>& __y)
 {
     if (!static_cast<bool>(__y))
         return false;
     if (!static_cast<bool>(__x))
         return true;
-    return less<_Tp>{}(*__x, *__y);
+    return *__x < *__y;
 }
 
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
 constexpr
 bool
+operator>(const optional<_Tp>& __x, const optional<_Tp>& __y)
+{
+    return __y < __x;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator<=(const optional<_Tp>& __x, const optional<_Tp>& __y)
+{
+    return !(__y < __x);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator>=(const optional<_Tp>& __x, const optional<_Tp>& __y)
+{
+    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);
@@ -608,6 +657,24 @@ 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;
@@ -626,6 +693,61 @@ 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
+bool
 operator==(const optional<_Tp>& __x, const _Tp& __v)
 {
     return static_cast<bool>(__x) ? *__x == __v : false;
@@ -644,6 +766,24 @@ template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
 constexpr
 bool
+operator!=(const optional<_Tp>& __x, const _Tp& __v)
+{
+    return static_cast<bool>(__x) ? !(*__x == __v) : true;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator!=(const _Tp& __v, const optional<_Tp>& __x)
+{
+    return static_cast<bool>(__x) ? !(*__x == __v) : true;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
 operator<(const optional<_Tp>& __x, const _Tp& __v)
 {
     return static_cast<bool>(__x) ? less<_Tp>{}(*__x, __v) : true;
@@ -660,6 +800,61 @@ operator<(const _Tp& __v, const optional<_Tp>& __x)
 
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator<=(const optional<_Tp>& __x, const _Tp& __v)
+{
+    return !(__x > __v);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator<=(const _Tp& __v, const optional<_Tp>& __x)
+{
+    return !(__v > __x);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator>(const optional<_Tp>& __x, const _Tp& __v)
+{
+    return static_cast<bool>(__x) ? __v < __x : false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator>(const _Tp& __v, const optional<_Tp>& __x)
+{
+    return static_cast<bool>(__x) ? __x < __v : true;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator>=(const optional<_Tp>& __x, const _Tp& __v)
+{
+    return !(__x < __v);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator>=(const _Tp& __v, const optional<_Tp>& __x)
+{
+    return !(__v < __x);
+}
+
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
 void
 swap(optional<_Tp>& __x, optional<_Tp>& __y) noexcept(noexcept(__x.swap(__y)))
 {
@@ -675,7 +870,7 @@ make_optional(_Tp&& __v)
     return optional<typename decay<_Tp>::type>(_VSTD::forward<_Tp>(__v));
 }
 
-}}}  // namespace std::experimental::__library_fundamentals_v1
+_LIBCPP_END_NAMESPACE_LFTS
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
@@ -696,4 +891,4 @@ _LIBCPP_END_NAMESPACE_STD
 
 #endif  // _LIBCPP_STD_VER > 11
 
-#endif  // _LIBCPP_ARRAY
+#endif  // _LIBCPP_OPTIONAL
diff --git a/contrib/libc++/include/experimental/string_view b/contrib/libc++/include/experimental/string_view
new file mode 100644
index 0000000..d423f39
--- /dev/null
+++ b/contrib/libc++/include/experimental/string_view
@@ -0,0 +1,815 @@
+// -*- C++ -*-
+//===------------------------ string_view ---------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_LFTS_STRING_VIEW
+#define _LIBCPP_LFTS_STRING_VIEW
+
+/*
+string_view synopsis
+
+namespace std {
+ namespace experimental {
+  inline namespace library_fundamentals_v1 {
+
+    // 7.2, Class template basic_string_view
+    template<class charT, class traits = char_traits<charT>>
+        class basic_string_view;
+
+    // 7.9, basic_string_view non-member comparison functions
+    template<class charT, class traits>
+    constexpr bool operator==(basic_string_view<charT, traits> x,
+                              basic_string_view<charT, traits> y) noexcept;
+    template<class charT, class traits>
+    constexpr bool operator!=(basic_string_view<charT, traits> x,
+                              basic_string_view<charT, traits> y) noexcept;
+    template<class charT, class traits>
+    constexpr bool operator< (basic_string_view<charT, traits> x,
+                                 basic_string_view<charT, traits> y) noexcept;
+    template<class charT, class traits>
+    constexpr bool operator> (basic_string_view<charT, traits> x,
+                              basic_string_view<charT, traits> y) noexcept;
+    template<class charT, class traits>
+    constexpr bool operator<=(basic_string_view<charT, traits> x,
+                                 basic_string_view<charT, traits> y) noexcept;
+    template<class charT, class traits>
+    constexpr bool operator>=(basic_string_view<charT, traits> x,
+                              basic_string_view<charT, traits> y) noexcept;
+    // see below, sufficient additional overloads of comparison functions
+
+    // 7.10, Inserters and extractors
+    template<class charT, class traits>
+      basic_ostream<charT, traits>&
+        operator<<(basic_ostream<charT, traits>& os,
+                   basic_string_view<charT, traits> str);
+
+    // basic_string_view typedef names
+    typedef basic_string_view<char> string_view;
+    typedef basic_string_view<char16_t> u16string_view;
+    typedef basic_string_view<char32_t> u32string_view;
+    typedef basic_string_view<wchar_t> wstring_view;
+
+    template<class charT, class traits = char_traits<charT>>
+    class basic_string_view {
+      public:
+      // types
+      typedef traits traits_type;
+      typedef charT value_type;
+      typedef charT* pointer;
+      typedef const charT* const_pointer;
+      typedef charT& reference;
+      typedef const charT& const_reference;
+      typedef implementation-defined const_iterator;
+      typedef const_iterator iterator;
+      typedef reverse_iterator<const_iterator> const_reverse_iterator;
+      typedef const_reverse_iterator reverse_iterator;
+      typedef size_t size_type;
+      typedef ptrdiff_t difference_type;
+      static constexpr size_type npos = size_type(-1);
+
+      // 7.3, basic_string_view constructors and assignment operators
+      constexpr basic_string_view() noexcept;
+      constexpr basic_string_view(const basic_string_view&) noexcept = default;
+      basic_string_view& operator=(const basic_string_view&) noexcept = default;
+      template<class Allocator>
+      basic_string_view(const basic_string<charT, traits, Allocator>& str) noexcept;
+      constexpr basic_string_view(const charT* str);
+      constexpr basic_string_view(const charT* str, size_type len);
+
+      // 7.4, basic_string_view iterator support
+      constexpr const_iterator begin() const noexcept;
+      constexpr const_iterator end() const noexcept;
+      constexpr const_iterator cbegin() const noexcept;
+      constexpr const_iterator cend() const noexcept;
+      const_reverse_iterator rbegin() const noexcept;
+      const_reverse_iterator rend() const noexcept;
+      const_reverse_iterator crbegin() const noexcept;
+      const_reverse_iterator crend() const noexcept;
+
+      // 7.5, basic_string_view capacity
+      constexpr size_type size() const noexcept;
+      constexpr size_type length() const noexcept;
+      constexpr size_type max_size() const noexcept;
+      constexpr bool empty() const noexcept;
+
+      // 7.6, basic_string_view element access
+      constexpr const_reference operator[](size_type pos) const;
+      constexpr const_reference at(size_type pos) const;
+      constexpr const_reference front() const;
+      constexpr const_reference back() const;
+      constexpr const_pointer data() const noexcept;
+
+      // 7.7, basic_string_view modifiers
+      constexpr void clear() noexcept;
+      constexpr void remove_prefix(size_type n);
+      constexpr void remove_suffix(size_type n);
+      constexpr void swap(basic_string_view& s) noexcept;
+
+      // 7.8, basic_string_view string operations
+      template<class Allocator>
+      explicit operator basic_string<charT, traits, Allocator>() const;
+      template<class Allocator = allocator<charT>>
+      basic_string<charT, traits, Allocator> to_string(
+        const Allocator& a = Allocator()) const;
+
+      size_type copy(charT* s, size_type n, size_type pos = 0) const;
+
+      constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;
+      constexpr int compare(basic_string_view s) const noexcept;
+      constexpr int compare(size_type pos1, size_type n1, basic_string_view s) const;
+      constexpr int compare(size_type pos1, size_type n1,
+                            basic_string_view s, size_type pos2, size_type n2) const;
+      constexpr int compare(const charT* s) const;
+      constexpr int compare(size_type pos1, size_type n1, const charT* s) const;
+      constexpr int compare(size_type pos1, size_type n1,
+                            const charT* s, size_type n2) const;
+      constexpr size_type find(basic_string_view s, size_type pos = 0) const noexcept;
+      constexpr size_type find(charT c, size_type pos = 0) const noexcept;
+      constexpr size_type find(const charT* s, size_type pos, size_type n) const;
+      constexpr size_type find(const charT* s, size_type pos = 0) const;
+      constexpr size_type rfind(basic_string_view s, size_type pos = npos) const noexcept;
+      constexpr size_type rfind(charT c, size_type pos = npos) const noexcept;
+      constexpr size_type rfind(const charT* s, size_type pos, size_type n) const;
+      constexpr size_type rfind(const charT* s, size_type pos = npos) const;
+      constexpr size_type find_first_of(basic_string_view s, size_type pos = 0) const noexcept;
+      constexpr size_type find_first_of(charT c, size_type pos = 0) const noexcept;
+      constexpr size_type find_first_of(const charT* s, size_type pos, size_type n) const;
+      constexpr size_type find_first_of(const charT* s, size_type pos = 0) const;
+      constexpr size_type find_last_of(basic_string_view s, size_type pos = npos) const noexcept;
+      constexpr size_type find_last_of(charT c, size_type pos = npos) const noexcept;
+      constexpr size_type find_last_of(const charT* s, size_type pos, size_type n) const;
+      constexpr size_type find_last_of(const charT* s, size_type pos = npos) const;
+      constexpr size_type find_first_not_of(basic_string_view s, size_type pos = 0) const noexcept;
+      constexpr size_type find_first_not_of(charT c, size_type pos = 0) const noexcept;
+      constexpr size_type find_first_not_of(const charT* s, size_type pos, size_type n) const;
+      constexpr size_type find_first_not_of(const charT* s, size_type pos = 0) const;
+      constexpr size_type find_last_not_of(basic_string_view s, size_type pos = npos) const noexcept;
+      constexpr size_type find_last_not_of(charT c, size_type pos = npos) const noexcept;
+      constexpr size_type find_last_not_of(const charT* s, size_type pos, size_type n) const;
+      constexpr size_type find_last_not_of(const charT* s, size_type pos = npos) const;
+
+     private:
+      const_pointer data_;  // exposition only
+      size_type     size_;  // exposition only
+    };
+
+  }  // namespace fundamentals_v1
+ }  // namespace experimental
+
+  // 7.11, Hash support
+  template <class T> struct hash;
+  template <> struct hash<experimental::string_view>;
+  template <> struct hash<experimental::u16string_view>;
+  template <> struct hash<experimental::u32string_view>;
+  template <> struct hash<experimental::wstring_view>;
+
+}  // namespace std
+
+
+*/
+
+#include <experimental/__config>
+
+#include <string>
+#include <algorithm>
+#include <iterator>
+#include <ostream>
+#include <iomanip>
+
+#include <__debug>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_LFTS
+
+    template<class _CharT, class _Traits = _VSTD::char_traits<_CharT> >
+    class _LIBCPP_TYPE_VIS_ONLY basic_string_view {
+    public:
+        // types
+        typedef _Traits                                    traits_type;
+        typedef _CharT                                     value_type;
+        typedef const _CharT*                              pointer;
+        typedef const _CharT*                              const_pointer;
+        typedef const _CharT&                              reference;
+        typedef const _CharT&                              const_reference;
+        typedef const_pointer                              const_iterator; // See [string.view.iterators]
+        typedef const_iterator                             iterator;
+        typedef _VSTD::reverse_iterator<const_iterator>    const_reverse_iterator;
+        typedef const_reverse_iterator                     reverse_iterator;
+        typedef size_t                                     size_type;
+        typedef ptrdiff_t                                  difference_type;
+        static _LIBCPP_CONSTEXPR const size_type npos = -1; // size_type(-1);
+
+        // [string.view.cons], construct/copy
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        basic_string_view() _NOEXCEPT : __data (nullptr), __size(0) {}
+
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        basic_string_view(const basic_string_view&) _NOEXCEPT = default;
+
+        _LIBCPP_INLINE_VISIBILITY
+        basic_string_view& operator=(const basic_string_view&) _NOEXCEPT = default;
+
+        template<class _Allocator>
+        _LIBCPP_INLINE_VISIBILITY
+        basic_string_view(const basic_string<_CharT, _Traits, _Allocator>& __str) _NOEXCEPT
+            : __data (__str.data()), __size(__str.size()) {}
+
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        basic_string_view(const _CharT* __s, size_type __len)
+            : __data(__s), __size(__len)
+        {
+//             _LIBCPP_ASSERT(__len == 0 || __s != nullptr, "string_view::string_view(_CharT *, size_t): recieved nullptr");
+        }
+
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        basic_string_view(const _CharT* __s)
+            : __data(__s), __size(_Traits::length(__s)) {}
+
+        // [string.view.iterators], iterators
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        const_iterator begin()  const _NOEXCEPT { return cbegin(); }
+
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        const_iterator end()    const _NOEXCEPT { return cend(); }
+
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        const_iterator cbegin() const _NOEXCEPT { return __data; }
+
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        const_iterator cend()   const _NOEXCEPT { return __data + __size; }
+
+        _LIBCPP_INLINE_VISIBILITY
+        const_reverse_iterator rbegin()   const _NOEXCEPT { return const_reverse_iterator(cend()); }
+
+        _LIBCPP_INLINE_VISIBILITY
+        const_reverse_iterator rend()     const _NOEXCEPT { return const_reverse_iterator(cbegin()); }
+
+        _LIBCPP_INLINE_VISIBILITY
+        const_reverse_iterator crbegin()  const _NOEXCEPT { return const_reverse_iterator(cend()); }
+
+        _LIBCPP_INLINE_VISIBILITY
+        const_reverse_iterator crend()    const _NOEXCEPT { return const_reverse_iterator(cbegin()); }
+
+        // [string.view.capacity], capacity
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        size_type size()     const _NOEXCEPT { return __size; }
+
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        size_type length()   const _NOEXCEPT { return __size; }
+
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        size_type max_size() const _NOEXCEPT { return _VSTD::numeric_limits<size_type>::max(); }
+
+        _LIBCPP_CONSTEXPR bool _LIBCPP_INLINE_VISIBILITY
+        empty()         const _NOEXCEPT { return __size == 0; }
+
+        // [string.view.access], element access
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        const_reference operator[](size_type __pos) const { return __data[__pos]; }
+
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        const_reference at(size_type __pos) const
+        {
+            return __pos >= size()
+                ? throw out_of_range("string_view::at")
+                : __data[__pos];
+//             if (__pos >= size())
+//                 throw out_of_range("string_view::at");
+//             return __data[__pos]; 
+        }
+
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        const_reference front() const
+        {
+            return _LIBCPP_ASSERT(!empty(), "string_view::front(): string is empty"), __data[0];
+        }
+
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        const_reference back() const
+        {
+            return _LIBCPP_ASSERT(!empty(), "string_view::back(): string is empty"), __data[__size-1];
+        }
+
+        _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+        const_pointer data() const _NOEXCEPT { return __data; }
+
+        // [string.view.modifiers], modifiers:
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        void clear() _NOEXCEPT
+        {
+            __data = nullptr;
+            __size = 0;
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        void remove_prefix(size_type __n) _NOEXCEPT
+        {
+            _LIBCPP_ASSERT(n <= size(), "remove_prefix() can't remove more than size()");
+            __data += __n;
+            __size -= __n;
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        void remove_suffix(size_type __n) _NOEXCEPT
+        {
+            _LIBCPP_ASSERT(n <= size(), "remove_suffix() can't remove more than size()");
+            __size -= __n;
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        void swap(basic_string_view& __other) _NOEXCEPT
+        {
+            const value_type *__p = __data;
+            __data = __other.__data;
+            __other.__data = __p;
+
+            size_type __sz = __size;
+            __size = __other.__size;
+            __other.__size = __sz;
+//             _VSTD::swap( __data, __other.__data );
+//             _VSTD::swap( __size, __other.__size );
+        }
+
+        // [string.view.ops], string operations:
+        template<class _Allocator>
+        _LIBCPP_INLINE_VISIBILITY
+        _LIBCPP_EXPLICIT operator basic_string<_CharT, _Traits, _Allocator>() const
+        { return basic_string<_CharT, _Traits, _Allocator>( begin(), end()); }
+
+        template<class _Allocator = allocator<_CharT> >
+        _LIBCPP_INLINE_VISIBILITY
+        basic_string<_CharT, _Traits, _Allocator>
+        to_string( const _Allocator& __a = _Allocator()) const
+        { return basic_string<_CharT, _Traits, _Allocator> ( begin(), end(), __a ); }
+
+        size_type copy(_CharT* __s, size_type __n, size_type __pos = 0) const
+        {
+            if ( __pos > size())
+                throw out_of_range("string_view::copy");
+            size_type __rlen = _VSTD::min( __n, size() - __pos );
+            _VSTD::copy_n(begin() + __pos, __rlen, __s );
+            return __rlen;
+        }
+
+        _LIBCPP_CONSTEXPR
+        basic_string_view substr(size_type __pos = 0, size_type __n = npos) const
+        {
+//             if (__pos > size())
+//                 throw out_of_range("string_view::substr");
+//             size_type __rlen = _VSTD::min( __n, size() - __pos );
+//             return basic_string_view(data() + __pos, __rlen);
+            return __pos > size()
+                ? throw out_of_range("string_view::substr")
+                : basic_string_view(data() + __pos, _VSTD::min(__n, size() - __pos));
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 int compare(basic_string_view __sv) const _NOEXCEPT
+        {
+            size_type __rlen = _VSTD::min( size(), __sv.size());
+            int __retval = _Traits::compare(data(), __sv.data(), __rlen);
+            if ( __retval == 0 ) // first __rlen chars matched
+                __retval = size() == __sv.size() ? 0 : ( size() < __sv.size() ? -1 : 1 );
+            return __retval;
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        int compare(size_type __pos1, size_type __n1, basic_string_view __sv) const
+        {
+            return substr(__pos1, __n1).compare(__sv);
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        int compare(                       size_type __pos1, size_type __n1, 
+                    basic_string_view _sv, size_type __pos2, size_type __n2) const
+        {
+            return substr(__pos1, __n1).compare(_sv.substr(__pos2, __n2));
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        int compare(const _CharT* __s) const
+        {
+            return compare(basic_string_view(__s));
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        int compare(size_type __pos1, size_type __n1, const _CharT* __s) const
+        {
+            return substr(__pos1, __n1).compare(basic_string_view(__s));
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        int compare(size_type __pos1, size_type __n1, const _CharT* __s, size_type __n2) const
+        {
+            return substr(__pos1, __n1).compare(basic_string_view(__s, __n2));
+        }
+
+        // find
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT
+        {
+            _LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find(): recieved nullptr");
+            return _VSTD::__str_find<value_type, size_type, traits_type, npos>
+                (data(), size(), __s.data(), __pos, __s.size());
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find(_CharT __c, size_type __pos = 0) const _NOEXCEPT
+        {
+            return _VSTD::__str_find<value_type, size_type, traits_type, npos>
+                (data(), size(), __c, __pos);
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find(const _CharT* __s, size_type __pos, size_type __n) const
+        {
+            _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find(): recieved nullptr");
+            return _VSTD::__str_find<value_type, size_type, traits_type, npos>
+                (data(), size(), __s, __pos, __n);
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find(const _CharT* __s, size_type __pos = 0) const
+        {
+            _LIBCPP_ASSERT(__s != nullptr, "string_view::find(): recieved nullptr");
+            return _VSTD::__str_find<value_type, size_type, traits_type, npos>
+                (data(), size(), __s, __pos, traits_type::length(__s));
+        }
+
+        // rfind
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type rfind(basic_string_view __s, size_type __pos = npos) const _NOEXCEPT
+        {
+            _LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find(): recieved nullptr");
+            return _VSTD::__str_rfind<value_type, size_type, traits_type, npos>
+                (data(), size(), __s.data(), __pos, __s.size());
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type rfind(_CharT __c, size_type __pos = npos) const _NOEXCEPT
+        {
+            return _VSTD::__str_rfind<value_type, size_type, traits_type, npos>
+                (data(), size(), __c, __pos);
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type rfind(const _CharT* __s, size_type __pos, size_type __n) const
+        {
+            _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::rfind(): recieved nullptr");
+            return _VSTD::__str_rfind<value_type, size_type, traits_type, npos>
+                (data(), size(), __s, __pos, __n);
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type rfind(const _CharT* __s, size_type __pos=npos) const
+        {
+            _LIBCPP_ASSERT(__s != nullptr, "string_view::rfind(): recieved nullptr");
+            return _VSTD::__str_rfind<value_type, size_type, traits_type, npos>
+                (data(), size(), __s, __pos, traits_type::length(__s));
+        }
+
+        // find_first_of
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_first_of(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT
+        {
+            _LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find_first_of(): recieved nullptr");
+            return _VSTD::__str_find_first_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __s.data(), __pos, __s.size());
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_first_of(_CharT __c, size_type __pos = 0) const _NOEXCEPT
+        { return find(__c, __pos); }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_first_of(const _CharT* __s, size_type __pos, size_type __n) const
+        {
+            _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find_first_of(): recieved nullptr");
+            return _VSTD::__str_find_first_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __s, __pos, __n);
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_first_of(const _CharT* __s, size_type __pos=0) const
+        {
+            _LIBCPP_ASSERT(__s != nullptr, "string_view::find_first_of(): recieved nullptr");
+            return _VSTD::__str_find_first_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __s, __pos, traits_type::length(__s));
+        }
+
+        // find_last_of
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_last_of(basic_string_view __s, size_type __pos=npos) const _NOEXCEPT
+        {
+            _LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find_last_of(): recieved nullptr");
+            return _VSTD::__str_find_last_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __s.data(), __pos, __s.size());
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_last_of(_CharT __c, size_type __pos = npos) const _NOEXCEPT
+        { return rfind(__c, __pos); }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_last_of(const _CharT* __s, size_type __pos, size_type __n) const
+        {
+            _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find_last_of(): recieved nullptr");
+            return _VSTD::__str_find_last_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __s, __pos, __n);
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_last_of(const _CharT* __s, size_type __pos=npos) const
+        {
+            _LIBCPP_ASSERT(__s != nullptr, "string_view::find_last_of(): recieved nullptr");
+            return _VSTD::__str_find_last_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __s, __pos, traits_type::length(__s));
+        }
+
+        // find_first_not_of
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_first_not_of(basic_string_view __s, size_type __pos=0) const _NOEXCEPT
+        {
+            _LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find_first_not_of(): recieved nullptr");
+            return _VSTD::__str_find_first_not_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __s.data(), __pos, __s.size());
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_first_not_of(_CharT __c, size_type __pos=0) const _NOEXCEPT
+        {
+            return _VSTD::__str_find_first_not_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __c, __pos);
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_first_not_of(const _CharT* __s, size_type __pos, size_type __n) const
+        {
+            _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find_first_not_of(): recieved nullptr");
+            return _VSTD::__str_find_first_not_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __s, __pos, __n);
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_first_not_of(const _CharT* __s, size_type __pos=0) const
+        {
+            _LIBCPP_ASSERT(__s != nullptr, "string_view::find_first_not_of(): recieved nullptr");
+            return _VSTD::__str_find_first_not_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __s, __pos, traits_type::length(__s));
+        }
+
+        // find_last_not_of
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_last_not_of(basic_string_view __s, size_type __pos=npos) const _NOEXCEPT
+        {
+            _LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find_last_not_of(): recieved nullptr");
+            return _VSTD::__str_find_last_not_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __s.data(), __pos, __s.size());
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_last_not_of(_CharT __c, size_type __pos=npos) const _NOEXCEPT
+        {
+            return _VSTD::__str_find_last_not_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __c, __pos);
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_last_not_of(const _CharT* __s, size_type __pos, size_type __n) const
+        {
+            _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find_last_not_of(): recieved nullptr");
+            return _VSTD::__str_find_last_not_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __s, __pos, __n);
+        }
+
+        _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+        size_type find_last_not_of(const _CharT* __s, size_type __pos=npos) const
+        {
+            _LIBCPP_ASSERT(__s != nullptr, "string_view::find_last_not_of(): recieved nullptr");
+            return _VSTD::__str_find_last_not_of<value_type, size_type, traits_type, npos>
+                (data(), size(), __s, __pos, traits_type::length(__s));
+        }
+
+    private:
+        const   value_type* __data;
+        size_type           __size;
+    };
+
+
+    // [string.view.comparison]
+    // operator ==
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator==(basic_string_view<_CharT, _Traits> __lhs,
+                    basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+    {
+        if ( __lhs.size() != __rhs.size()) return false;
+        return __lhs.compare(__rhs) == 0;
+    }
+
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator==(basic_string_view<_CharT, _Traits> __lhs,
+                    typename _VSTD::common_type<basic_string_view<_CharT, _Traits> >::type __rhs) _NOEXCEPT
+    {
+        if ( __lhs.size() != __rhs.size()) return false;
+        return __lhs.compare(__rhs) == 0;
+    }
+
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator==(typename _VSTD::common_type<basic_string_view<_CharT, _Traits> >::type __lhs, 
+                    basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+    {
+        if ( __lhs.size() != __rhs.size()) return false;
+        return __lhs.compare(__rhs) == 0;
+    }
+
+
+    // operator !=
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator!=(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+    {
+        if ( __lhs.size() != __rhs.size())
+            return true;
+        return __lhs.compare(__rhs) != 0;
+    }
+
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator!=(basic_string_view<_CharT, _Traits> __lhs,
+                    typename _VSTD::common_type<basic_string_view<_CharT, _Traits> >::type __rhs) _NOEXCEPT
+    {
+        if ( __lhs.size() != __rhs.size())
+            return true;
+        return __lhs.compare(__rhs) != 0;
+    }
+
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator!=(typename _VSTD::common_type<basic_string_view<_CharT, _Traits> >::type __lhs, 
+                    basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+    {
+        if ( __lhs.size() != __rhs.size())
+            return true;
+        return __lhs.compare(__rhs) != 0;
+    }
+
+
+    // operator <
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator<(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+    {
+        return __lhs.compare(__rhs) < 0;
+    }
+
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator<(basic_string_view<_CharT, _Traits> __lhs,
+                    typename _VSTD::common_type<basic_string_view<_CharT, _Traits> >::type __rhs) _NOEXCEPT
+    {
+        return __lhs.compare(__rhs) < 0;
+    }
+
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator<(typename _VSTD::common_type<basic_string_view<_CharT, _Traits> >::type __lhs, 
+                    basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+    {
+        return __lhs.compare(__rhs) < 0;
+    }
+
+
+    // operator >
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator> (basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+    {
+        return __lhs.compare(__rhs) > 0;
+    }
+
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator>(basic_string_view<_CharT, _Traits> __lhs,
+                    typename _VSTD::common_type<basic_string_view<_CharT, _Traits> >::type __rhs) _NOEXCEPT
+    {
+        return __lhs.compare(__rhs) > 0;
+    }
+
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator>(typename _VSTD::common_type<basic_string_view<_CharT, _Traits> >::type __lhs, 
+                    basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+    {
+        return __lhs.compare(__rhs) > 0;
+    }
+
+
+    // operator <=
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator<=(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+    {
+        return __lhs.compare(__rhs) <= 0;
+    }
+
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator<=(basic_string_view<_CharT, _Traits> __lhs,
+                    typename _VSTD::common_type<basic_string_view<_CharT, _Traits> >::type __rhs) _NOEXCEPT
+    {
+        return __lhs.compare(__rhs) <= 0;
+    }
+
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator<=(typename _VSTD::common_type<basic_string_view<_CharT, _Traits> >::type __lhs, 
+                    basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+    {
+        return __lhs.compare(__rhs) <= 0;
+    }
+
+
+    // operator >=
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator>=(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+    {
+        return __lhs.compare(__rhs) >= 0;
+    }
+
+
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator>=(basic_string_view<_CharT, _Traits> __lhs,
+                    typename _VSTD::common_type<basic_string_view<_CharT, _Traits> >::type __rhs) _NOEXCEPT
+    {
+        return __lhs.compare(__rhs) >= 0;
+    }
+
+    template<class _CharT, class _Traits>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool operator>=(typename _VSTD::common_type<basic_string_view<_CharT, _Traits> >::type __lhs, 
+                    basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+    {
+        return __lhs.compare(__rhs) >= 0;
+    }
+
+
+    // [string.view.io]
+    template<class _CharT, class _Traits>
+    basic_ostream<_CharT, _Traits>&
+    operator<<(basic_ostream<_CharT, _Traits>& __os, basic_string_view<_CharT, _Traits> __sv)
+    {
+        return _VSTD::__put_character_sequence(__os, __sv.data(), __sv.size());
+    }
+
+  typedef basic_string_view<char>     string_view;
+  typedef basic_string_view<char16_t> u16string_view;
+  typedef basic_string_view<char32_t> u32string_view;
+  typedef basic_string_view<wchar_t>  wstring_view;
+
+_LIBCPP_END_NAMESPACE_LFTS
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// [string.view.hash]
+// Shamelessly stolen from <string>
+template<class _CharT, class _Traits>
+struct _LIBCPP_TYPE_VIS_ONLY hash<std::experimental::basic_string_view<_CharT, _Traits> >
+    : public unary_function<std::experimental::basic_string_view<_CharT, _Traits>, size_t>
+{
+    size_t operator()(const std::experimental::basic_string_view<_CharT, _Traits>& __val) const _NOEXCEPT;
+};
+
+template<class _CharT, class _Traits>
+size_t
+hash<std::experimental::basic_string_view<_CharT, _Traits> >::operator()(
+        const std::experimental::basic_string_view<_CharT, _Traits>& __val) const _NOEXCEPT
+{
+    return __do_string_hash(__val.data(), __val.data() + __val.size());
+}
+
+#if _LIBCPP_STD_VER > 11
+template <class _CharT, class _Traits>
+__quoted_output_proxy<_CharT, const _CharT *, _Traits>
+quoted ( std::experimental::basic_string_view <_CharT, _Traits> __sv,
+             _CharT __delim = _CharT('"'), _CharT __escape=_CharT('\\'))
+{
+    return __quoted_output_proxy<_CharT, const _CharT *, _Traits> 
+         ( __sv.data(), __sv.data() + __sv.size(), __delim, __escape );
+}
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_LFTS_STRING_VIEW
diff --git a/contrib/libc++/include/experimental/type_traits b/contrib/libc++/include/experimental/type_traits
new file mode 100644
index 0000000..ab2c8cd
--- /dev/null
+++ b/contrib/libc++/include/experimental/type_traits
@@ -0,0 +1,423 @@
+// -*- C++ -*-
+//===-------------------------- type_traits -------------------------------===//
+//
+//                     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_EXPERIMENTAL_TYPE_TRAITS
+#define _LIBCPP_EXPERIMENTAL_TYPE_TRAITS
+
+/**
+    experimental/type_traits synopsis
+
+// C++1y
+#include <type_traits>
+
+namespace std {
+namespace experimental {
+inline namespace fundamentals_v1 {
+
+  // See C++14 20.10.4.1, primary type categories
+  template <class T> constexpr bool is_void_v
+    = is_void<T>::value;
+  template <class T> constexpr bool is_null_pointer_v
+    = is_null_pointer<T>::value;
+  template <class T> constexpr bool is_integral_v
+    = is_integral<T>::value;
+  template <class T> constexpr bool is_floating_point_v
+    = is_floating_point<T>::value;
+  template <class T> constexpr bool is_array_v
+    = is_array<T>::value;
+  template <class T> constexpr bool is_pointer_v
+    = is_pointer<T>::value;
+  template <class T> constexpr bool is_lvalue_reference_v
+    = is_lvalue_reference<T>::value;
+  template <class T> constexpr bool is_rvalue_reference_v
+    = is_rvalue_reference<T>::value;
+  template <class T> constexpr bool is_member_object_pointer_v
+    = is_member_object_pointer<T>::value;
+  template <class T> constexpr bool is_member_function_pointer_v
+    = is_member_function_pointer<T>::value;
+  template <class T> constexpr bool is_enum_v
+    = is_enum<T>::value;
+  template <class T> constexpr bool is_union_v
+    = is_union<T>::value;
+  template <class T> constexpr bool is_class_v
+    = is_class<T>::value;
+  template <class T> constexpr bool is_function_v
+    = is_function<T>::value;
+
+  // See C++14 20.10.4.2, composite type categories
+  template <class T> constexpr bool is_reference_v
+    = is_reference<T>::value;
+  template <class T> constexpr bool is_arithmetic_v
+    = is_arithmetic<T>::value;
+  template <class T> constexpr bool is_fundamental_v
+    = is_fundamental<T>::value;
+  template <class T> constexpr bool is_object_v
+    = is_object<T>::value;
+  template <class T> constexpr bool is_scalar_v
+    = is_scalar<T>::value;
+  template <class T> constexpr bool is_compound_v
+    = is_compound<T>::value;
+  template <class T> constexpr bool is_member_pointer_v
+    = is_member_pointer<T>::value;
+
+  // See C++14 20.10.4.3, type properties
+  template <class T> constexpr bool is_const_v
+    = is_const<T>::value;
+  template <class T> constexpr bool is_volatile_v
+    = is_volatile<T>::value;
+  template <class T> constexpr bool is_trivial_v
+    = is_trivial<T>::value;
+  template <class T> constexpr bool is_trivially_copyable_v
+    = is_trivially_copyable<T>::value;
+  template <class T> constexpr bool is_standard_layout_v
+    = is_standard_layout<T>::value;
+  template <class T> constexpr bool is_pod_v
+    = is_pod<T>::value;
+  template <class T> constexpr bool is_literal_type_v
+    = is_literal_type<T>::value;
+  template <class T> constexpr bool is_empty_v
+    = is_empty<T>::value;
+  template <class T> constexpr bool is_polymorphic_v
+    = is_polymorphic<T>::value;
+  template <class T> constexpr bool is_abstract_v
+    = is_abstract<T>::value;
+  template <class T> constexpr bool is_final_v
+    = is_final<T>::value;
+  template <class T> constexpr bool is_signed_v
+    = is_signed<T>::value;
+  template <class T> constexpr bool is_unsigned_v
+    = is_unsigned<T>::value;
+  template <class T, class... Args> constexpr bool is_constructible_v
+    = is_constructible<T, Args...>::value;
+  template <class T> constexpr bool is_default_constructible_v
+    = is_default_constructible<T>::value;
+  template <class T> constexpr bool is_copy_constructible_v
+    = is_copy_constructible<T>::value;
+  template <class T> constexpr bool is_move_constructible_v
+    = is_move_constructible<T>::value;
+  template <class T, class U> constexpr bool is_assignable_v
+    = is_assignable<T, U>::value;
+  template <class T> constexpr bool is_copy_assignable_v
+    = is_copy_assignable<T>::value;
+  template <class T> constexpr bool is_move_assignable_v
+    = is_move_assignable<T>::value;
+  template <class T> constexpr bool is_destructible_v
+    = is_destructible<T>::value;
+  template <class T, class... Args> constexpr bool is_trivially_constructible_v
+    = is_trivially_constructible<T, Args...>::value;
+  template <class T> constexpr bool is_trivially_default_constructible_v
+    = is_trivially_default_constructible<T>::value;
+  template <class T> constexpr bool is_trivially_copy_constructible_v
+    = is_trivially_copy_constructible<T>::value;
+  template <class T> constexpr bool is_trivially_move_constructible_v
+    = is_trivially_move_constructible<T>::value;
+  template <class T, class U> constexpr bool is_trivially_assignable_v
+    = is_trivially_assignable<T, U>::value;
+  template <class T> constexpr bool is_trivially_copy_assignable_v
+    = is_trivially_copy_assignable<T>::value;
+  template <class T> constexpr bool is_trivially_move_assignable_v
+    = is_trivially_move_assignable<T>::value;
+  template <class T> constexpr bool is_trivially_destructible_v
+    = is_trivially_destructible<T>::value;
+  template <class T, class... Args> constexpr bool is_nothrow_constructible_v
+    = is_nothrow_constructible<T, Args...>::value;
+  template <class T> constexpr bool is_nothrow_default_constructible_v
+    = is_nothrow_default_constructible<T>::value;
+  template <class T> constexpr bool is_nothrow_copy_constructible_v
+    = is_nothrow_copy_constructible<T>::value;
+  template <class T> constexpr bool is_nothrow_move_constructible_v
+    = is_nothrow_move_constructible<T>::value;
+  template <class T, class U> constexpr bool is_nothrow_assignable_v
+    = is_nothrow_assignable<T, U>::value;
+  template <class T> constexpr bool is_nothrow_copy_assignable_v
+    = is_nothrow_copy_assignable<T>::value;
+  template <class T> constexpr bool is_nothrow_move_assignable_v
+    = is_nothrow_move_assignable<T>::value;
+  template <class T> constexpr bool is_nothrow_destructible_v
+    = is_nothrow_destructible<T>::value;
+  template <class T> constexpr bool has_virtual_destructor_v
+    = has_virtual_destructor<T>::value;
+
+  // See C++14 20.10.5, type property queries
+  template <class T> constexpr size_t alignment_of_v
+    = alignment_of<T>::value;
+  template <class T> constexpr size_t rank_v
+    = rank<T>::value;
+  template <class T, unsigned I = 0> constexpr size_t extent_v
+    = extent<T, I>::value;
+
+  // See C++14 20.10.6, type relations
+  template <class T, class U> constexpr bool is_same_v
+    = is_same<T, U>::value;
+  template <class Base, class Derived> constexpr bool is_base_of_v
+    = is_base_of<Base, Derived>::value;
+  template <class From, class To> constexpr bool is_convertible_v
+    = is_convertible<From, To>::value;
+
+  // 3.3.2, Other type transformations
+  template <class> class invocation_type; // not defined
+  template <class F, class... ArgTypes> class invocation_type<F(ArgTypes...)>;
+  template <class> class raw_invocation_type; // not defined
+  template <class F, class... ArgTypes> class raw_invocation_type<F(ArgTypes...)>;
+
+  template <class T>
+    using invocation_type_t = typename invocation_type<T>::type;
+  template <class T>
+    using raw_invocation_type_t = typename raw_invocation_type<T>::type;
+
+} // namespace fundamentals_v1
+} // namespace experimental
+} // namespace std
+
+ */
+
+#include <experimental/__config>
+
+#if _LIBCPP_STD_VER > 11
+
+#include <type_traits>
+
+_LIBCPP_BEGIN_NAMESPACE_LFTS
+
+#if __has_feature(cxx_variable_templates)
+
+// C++14 20.10.4.1, primary type categories
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_void_v
+    = is_void<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_null_pointer_v
+    = is_null_pointer<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_integral_v
+    = is_integral<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_floating_point_v
+    = is_floating_point<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_array_v
+    = is_array<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_pointer_v
+    = is_pointer<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_lvalue_reference_v
+    = is_lvalue_reference<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_rvalue_reference_v
+    = is_rvalue_reference<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_member_object_pointer_v
+    = is_member_object_pointer<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_member_function_pointer_v
+    = is_member_function_pointer<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_enum_v
+    = is_enum<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_union_v
+    = is_union<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_class_v
+    = is_class<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_function_v
+    = is_function<_Tp>::value;
+
+// C++14 20.10.4.2,  composite type categories
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_reference_v
+    = is_reference<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_arithmetic_v
+    = is_arithmetic<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_fundamental_v
+    = is_fundamental<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_object_v
+    = is_object<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_scalar_v
+    = is_scalar<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_compound_v
+    = is_compound<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_member_pointer_v
+    = is_member_pointer<_Tp>::value;
+
+// C++14 20.10.4.3, type properties
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_const_v
+    = is_const<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_volatile_v
+    = is_volatile<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_trivial_v
+    = is_trivial<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_trivially_copyable_v
+    = is_trivially_copyable<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_standard_layout_v
+    = is_standard_layout<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_pod_v
+    = is_pod<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_literal_type_v
+    = is_literal_type<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_empty_v
+    = is_empty<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_polymorphic_v
+    = is_polymorphic<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_abstract_v
+    = is_abstract<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_final_v
+    = is_final<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_signed_v
+    = is_signed<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_unsigned_v
+    = is_unsigned<_Tp>::value;
+
+template <class _Tp, class ..._Ts> _LIBCPP_CONSTEXPR bool is_constructible_v
+    = is_constructible<_Tp, _Ts...>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_default_constructible_v
+    = is_default_constructible<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_copy_constructible_v
+    = is_copy_constructible<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_move_constructible_v
+    = is_move_constructible<_Tp>::value;
+
+template <class _Tp, class _Up> _LIBCPP_CONSTEXPR bool is_assignable_v
+    = is_assignable<_Tp, _Up>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_copy_assignable_v
+    = is_copy_assignable<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_move_assignable_v
+    = is_move_assignable<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_destructible_v
+    = is_destructible<_Tp>::value;
+
+template <class _Tp, class ..._Ts> _LIBCPP_CONSTEXPR bool is_trivially_constructible_v
+    = is_trivially_constructible<_Tp, _Ts...>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_trivially_default_constructible_v
+    = is_trivially_default_constructible<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_trivially_copy_constructible_v
+    = is_trivially_copy_constructible<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_trivially_move_constructible_v
+    = is_trivially_move_constructible<_Tp>::value;
+
+template <class _Tp, class _Up> _LIBCPP_CONSTEXPR bool is_trivially_assignable_v
+    = is_trivially_assignable<_Tp, _Up>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_trivially_copy_assignable_v
+    = is_trivially_copy_assignable<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_trivially_move_assignable_v
+    = is_trivially_move_assignable<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_trivially_destructible_v
+    = is_trivially_destructible<_Tp>::value;
+
+template <class _Tp, class ..._Ts> _LIBCPP_CONSTEXPR bool is_nothrow_constructible_v
+    = is_nothrow_constructible<_Tp, _Ts...>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_nothrow_default_constructible_v
+    = is_nothrow_default_constructible<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_nothrow_copy_constructible_v
+    = is_nothrow_copy_constructible<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_nothrow_move_constructible_v
+    = is_nothrow_move_constructible<_Tp>::value;
+
+template <class _Tp, class _Up> _LIBCPP_CONSTEXPR bool is_nothrow_assignable_v
+    = is_nothrow_assignable<_Tp, _Up>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_nothrow_copy_assignable_v
+    = is_nothrow_copy_assignable<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_nothrow_move_assignable_v
+    = is_nothrow_move_assignable<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool is_nothrow_destructible_v
+    = is_nothrow_destructible<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR bool has_virtual_destructor_v
+    = has_virtual_destructor<_Tp>::value;
+
+// C++14 20.10.5, type properties queries
+
+template <class _Tp> _LIBCPP_CONSTEXPR size_t alignment_of_v
+    = alignment_of<_Tp>::value;
+
+template <class _Tp> _LIBCPP_CONSTEXPR size_t rank_v
+    = rank<_Tp>::value;
+
+template <class _Tp, unsigned _Id = 0> _LIBCPP_CONSTEXPR size_t extent_v
+    = extent<_Tp, _Id>::value;
+
+// C++14 20.10.6, type relations
+
+template <class _Tp, class _Up> _LIBCPP_CONSTEXPR bool is_same_v
+    = is_same<_Tp, _Up>::value;
+
+template <class _Tp, class _Up> _LIBCPP_CONSTEXPR bool is_base_of_v
+    = is_base_of<_Tp, _Up>::value;
+
+template <class _Tp, class _Up> _LIBCPP_CONSTEXPR bool is_convertible_v
+    = is_convertible<_Tp, _Up>::value;
+
+#endif /* __has_feature(cxx_variable_templates) */
+
+// 3.3.2, Other type transformations
+/*
+template <class>
+class _LIBCPP_TYPE_VIS_ONLY raw_invocation_type;
+
+template <class _Fn, class ..._Args>
+class _LIBCPP_TYPE_VIS_ONLY raw_invocation_type<_Fn(_Args...)>;
+
+template <class>
+class _LIBCPP_TYPE_VIS_ONLY invokation_type;
+
+template <class _Fn, class ..._Args>
+class _LIBCPP_TYPE_VIS_ONLY invokation_type<_Fn(_Args...)>;
+
+template <class _Tp>
+using invokation_type_t = typename invokation_type<_Tp>::type;
+
+template <class _Tp>
+using raw_invocation_type_t = typename raw_invocation_type<_Tp>::type;
+*/
+
+_LIBCPP_END_NAMESPACE_LFTS
+
+#endif /* _LIBCPP_STD_VER > 11 */
+
+#endif /* _LIBCPP_EXPERIMENTAL_TYPE_TRAITS */
diff --git a/contrib/libc++/include/experimental/utility b/contrib/libc++/include/experimental/utility
new file mode 100644
index 0000000..84e461a
--- /dev/null
+++ b/contrib/libc++/include/experimental/utility
@@ -0,0 +1,44 @@
+// -*- C++ -*-
+//===-------------------------- utility ----------------------------------===//
+//
+//                     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_EXPERIMENTAL_UTILITY
+#define _LIBCPP_EXPERIMENTAL_UTILITY
+
+/*
+    experimental/utility synopsis
+
+// C++1y
+
+#include <utility>
+
+namespace std {
+namespace experimental {
+inline namespace fundamentals_v1 {
+
+  3.1.2, erased-type placeholder
+  struct erased_type { };
+
+} // namespace fundamentals_v1
+} // namespace experimental
+} // namespace std
+
+ */
+
+# include <experimental/__config>
+
+# include <utility>
+
+_LIBCPP_BEGIN_NAMESPACE_LFTS
+
+  struct _LIBCPP_TYPE_VIS_ONLY erased_type { };
+
+_LIBCPP_END_NAMESPACE_LFTS
+
+#endif /* _LIBCPP_EXPERIMENTAL_UTILITY */