Update libc++ to 3.8.0. Excerpted list of fixes (with upstream revision

numbers):

r242679 Implement the plugin-based version of std::search. There are no
        searchers yet; those are coming soon.
r242682 Implement the default searcher for std::experimental::search.
r243728 Add <experimental/any> v2.
r245330 implement more of N4258 - Cleaning up noexcept in the standard
        library. Specifically add new noexcept stuff to vector and
	string's move-assignment operations
r245334 Fix PR22606 - Leak pthread_key with static storage duration to
        ensure all of thread-local destructors are called.
r245335 Fix PR23589: std::function doesn't recognize null pointer to
        varargs function.
r247036 Implementation of Boyer-Moore and Boyer-Moore-Horspool
        searchers for the LFTS.
r249325 Implement LWG#2063, and update the issues links to point to the
        github generated pages
r249738 Split <ctype.h> out of <cctype>.
r249739 Split <errno.h> out of <cerrno>.
r249740 Split <float.h> out of <cfloat>.
r249741 Split <inttypes.h> out of <cinttypes>.
r249742 Split <math.h> out of <cmath>.
r249743 Split <setjmp.h> out of <csetjmp>.
r249761 Split <stddef.h> out of <cstddef>.
r249798 Split <stdio.h> out of <cstdio>.
r249800 Split <stdlib.h> out of <cstdlib>.
r249889 Split <wchar.h> out of <cwchar>.
r249890 Split <wctype.h> out of <cwctype>.
r249929 Split <string.h> out of <cstring>.
r250254 ABI versioning macros for libc++.
r251246 Fix LWG#2244: basic_istream::seekg
r251247 Fix LWG#2127: Move-construction with raw_storage_iterator.
r251253 Fix LWG#2476: scoped_allocator_adaptor is not assignable
r251257 Fix LWG#2489: mem_fn() should be noexcept
r251618 Implement P0004R1 'Remove Deprecated iostreams aliases'
r251766 Implement the first part of P0006R0: Adopt Type Traits Variable
        Templates for C++17.
r252195 Implement P0092R1 for C++1z
r252350 Allow deque to handle incomplete types.
r252406 More of P0006R0: type traits variable aliases for C++17.
r252407 Implement LWG#2353: std::next is over-constrained
r252905 Implement P0074: Making owner_less more flexible
r253215 Implement P0013R1: Logical Operator Type Traits.
r253274 Implement P0007: Constant View: A proposal for a std::as_const
        helper function template.
r254119 Add static_assert to set/multiset/map/multimap/forward_list/deque
        that the allocator's value_type match the container's value_type.
r254283 Implement more of P0006; Type Traits Variable Templates.
r255941 LWG2485: get() should be overloaded for const tuple&&.
r256325 Fix LWG Issue #2367 - Fixing std::tuple and std::pair's default
        constructors.
r256652 Fix for ALL undefined behavior in <list>.
r256859 First half of LWG#2354: 'Unnecessary copying when inserting
        into maps with braced-init syntax'

Exp-run:	antoine
Relnotes:	yes

1 files changed, 125 insertions, 88 deletions

diff --git a/contrib/libc++/include/string b/contrib/libc++/include/string
index 6e63ab1..9150244 100644
--- a/contrib/libc++/include/string
+++ b/contrib/libc++/include/string
@@ -115,8 +115,8 @@ public:
     basic_string& operator=(const basic_string& str);
     basic_string& operator=(basic_string&& str)
         noexcept(
-             allocator_type::propagate_on_container_move_assignment::value &&
-             is_nothrow_move_assignable<allocator_type>::value);
+             allocator_type::propagate_on_container_move_assignment::value ||
+             allocator_type::is_always_equal::value ); // C++17
     basic_string& operator=(const value_type* s);
     basic_string& operator=(value_type c);
     basic_string& operator=(initializer_list<value_type>);
@@ -517,10 +517,14 @@ struct _LIBCPP_TYPE_VIS_ONLY char_traits
         {return __c1 < __c2;}
 
     static int              compare(const char_type* __s1, const char_type* __s2, size_t __n);
+    _LIBCPP_INLINE_VISIBILITY
     static size_t           length(const char_type* __s);
+    _LIBCPP_INLINE_VISIBILITY
     static const char_type* find(const char_type* __s, size_t __n, const char_type& __a);
     static char_type*       move(char_type* __s1, const char_type* __s2, size_t __n);
+    _LIBCPP_INLINE_VISIBILITY
     static char_type*       copy(char_type* __s1, const char_type* __s2, size_t __n);
+    _LIBCPP_INLINE_VISIBILITY
     static char_type*       assign(char_type* __s, size_t __n, char_type __a);
 
     static inline _LIBCPP_CONSTEXPR int_type  not_eof(int_type __c) _NOEXCEPT
@@ -550,7 +554,7 @@ char_traits<_CharT>::compare(const char_type* __s1, const char_type* __s2, size_
 }
 
 template <class _CharT>
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 size_t
 char_traits<_CharT>::length(const char_type* __s)
 {
@@ -561,7 +565,7 @@ char_traits<_CharT>::length(const char_type* __s)
 }
 
 template <class _CharT>
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 const _CharT*
 char_traits<_CharT>::find(const char_type* __s, size_t __n, const char_type& __a)
 {
@@ -595,7 +599,7 @@ char_traits<_CharT>::move(char_type* __s1, const char_type* __s2, size_t __n)
 }
 
 template <class _CharT>
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 _CharT*
 char_traits<_CharT>::copy(char_type* __s1, const char_type* __s2, size_t __n)
 {
@@ -607,7 +611,7 @@ char_traits<_CharT>::copy(char_type* __s1, const char_type* __s2, size_t __n)
 }
 
 template <class _CharT>
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 _CharT*
 char_traits<_CharT>::assign(char_type* __s, size_t __n, char_type __a)
 {
@@ -726,11 +730,17 @@ struct _LIBCPP_TYPE_VIS_ONLY char_traits<char16_t>
     static inline _LIBCPP_CONSTEXPR bool lt(char_type __c1, char_type __c2) _NOEXCEPT
         {return __c1 < __c2;}
 
+    _LIBCPP_INLINE_VISIBILITY
     static int              compare(const char_type* __s1, const char_type* __s2, size_t __n);
+    _LIBCPP_INLINE_VISIBILITY
     static size_t           length(const char_type* __s);
+    _LIBCPP_INLINE_VISIBILITY
     static const char_type* find(const char_type* __s, size_t __n, const char_type& __a);
+    _LIBCPP_INLINE_VISIBILITY
     static char_type*       move(char_type* __s1, const char_type* __s2, size_t __n);
+    _LIBCPP_INLINE_VISIBILITY
     static char_type*       copy(char_type* __s1, const char_type* __s2, size_t __n);
+    _LIBCPP_INLINE_VISIBILITY
     static char_type*       assign(char_type* __s, size_t __n, char_type __a);
 
     static inline _LIBCPP_CONSTEXPR int_type  not_eof(int_type __c) _NOEXCEPT
@@ -742,10 +752,10 @@ struct _LIBCPP_TYPE_VIS_ONLY char_traits<char16_t>
     static inline _LIBCPP_CONSTEXPR bool eq_int_type(int_type __c1, int_type __c2) _NOEXCEPT
         {return __c1 == __c2;}
     static inline _LIBCPP_CONSTEXPR int_type eof() _NOEXCEPT
-        {return int_type(0xDFFF);}
+        {return int_type(0xFFFF);}
 };
 
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 int
 char_traits<char16_t>::compare(const char_type* __s1, const char_type* __s2, size_t __n)
 {
@@ -759,7 +769,7 @@ char_traits<char16_t>::compare(const char_type* __s1, const char_type* __s2, siz
     return 0;
 }
 
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 size_t
 char_traits<char16_t>::length(const char_type* __s)
 {
@@ -769,7 +779,7 @@ char_traits<char16_t>::length(const char_type* __s)
     return __len;
 }
 
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 const char16_t*
 char_traits<char16_t>::find(const char_type* __s, size_t __n, const char_type& __a)
 {
@@ -782,7 +792,7 @@ char_traits<char16_t>::find(const char_type* __s, size_t __n, const char_type& _
     return 0;
 }
 
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 char16_t*
 char_traits<char16_t>::move(char_type* __s1, const char_type* __s2, size_t __n)
 {
@@ -802,7 +812,7 @@ char_traits<char16_t>::move(char_type* __s1, const char_type* __s2, size_t __n)
     return __r;
 }
 
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 char16_t*
 char_traits<char16_t>::copy(char_type* __s1, const char_type* __s2, size_t __n)
 {
@@ -813,7 +823,7 @@ char_traits<char16_t>::copy(char_type* __s1, const char_type* __s2, size_t __n)
     return __r;
 }
 
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 char16_t*
 char_traits<char16_t>::assign(char_type* __s, size_t __n, char_type __a)
 {
@@ -839,11 +849,17 @@ struct _LIBCPP_TYPE_VIS_ONLY char_traits<char32_t>
     static inline _LIBCPP_CONSTEXPR bool lt(char_type __c1, char_type __c2) _NOEXCEPT
         {return __c1 < __c2;}
 
+    _LIBCPP_INLINE_VISIBILITY
     static int              compare(const char_type* __s1, const char_type* __s2, size_t __n);
+    _LIBCPP_INLINE_VISIBILITY
     static size_t           length(const char_type* __s);
+    _LIBCPP_INLINE_VISIBILITY
     static const char_type* find(const char_type* __s, size_t __n, const char_type& __a);
+    _LIBCPP_INLINE_VISIBILITY
     static char_type*       move(char_type* __s1, const char_type* __s2, size_t __n);
+    _LIBCPP_INLINE_VISIBILITY
     static char_type*       copy(char_type* __s1, const char_type* __s2, size_t __n);
+    _LIBCPP_INLINE_VISIBILITY
     static char_type*       assign(char_type* __s, size_t __n, char_type __a);
 
     static inline _LIBCPP_CONSTEXPR int_type  not_eof(int_type __c) _NOEXCEPT
@@ -858,7 +874,7 @@ struct _LIBCPP_TYPE_VIS_ONLY char_traits<char32_t>
         {return int_type(0xFFFFFFFF);}
 };
 
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 int
 char_traits<char32_t>::compare(const char_type* __s1, const char_type* __s2, size_t __n)
 {
@@ -872,7 +888,7 @@ char_traits<char32_t>::compare(const char_type* __s1, const char_type* __s2, siz
     return 0;
 }
 
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 size_t
 char_traits<char32_t>::length(const char_type* __s)
 {
@@ -882,7 +898,7 @@ char_traits<char32_t>::length(const char_type* __s)
     return __len;
 }
 
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 const char32_t*
 char_traits<char32_t>::find(const char_type* __s, size_t __n, const char_type& __a)
 {
@@ -895,7 +911,7 @@ char_traits<char32_t>::find(const char_type* __s, size_t __n, const char_type& _
     return 0;
 }
 
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 char32_t*
 char_traits<char32_t>::move(char_type* __s1, const char_type* __s2, size_t __n)
 {
@@ -915,7 +931,7 @@ char_traits<char32_t>::move(char_type* __s1, const char_type* __s2, size_t __n)
     return __r;
 }
 
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 char32_t*
 char_traits<char32_t>::copy(char_type* __s1, const char_type* __s2, size_t __n)
 {
@@ -926,7 +942,7 @@ char_traits<char32_t>::copy(char_type* __s1, const char_type* __s2, size_t __n)
     return __r;
 }
 
-inline _LIBCPP_INLINE_VISIBILITY
+inline
 char32_t*
 char_traits<char32_t>::assign(char_type* __s, size_t __n, char_type __a)
 {
@@ -1185,7 +1201,31 @@ _LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_TYPE_VIS __basic_string_common<true>)
 #pragma warning( pop )
 #endif // _LIBCPP_MSVC
 
-#ifdef _LIBCPP_ALTERNATE_STRING_LAYOUT
+#ifdef _LIBCPP_NO_EXCEPTIONS
+template <class _Iter>
+struct __libcpp_string_gets_noexcept_iterator_impl : public true_type {};
+#elif defined(_LIBCPP_HAS_NO_NOEXCEPT)
+template <class _Iter>
+struct __libcpp_string_gets_noexcept_iterator_impl : public false_type {};
+#else
+template <class _Iter, bool = __is_forward_iterator<_Iter>::value>
+struct __libcpp_string_gets_noexcept_iterator_impl : public _LIBCPP_BOOL_CONSTANT((
+    noexcept(++(declval<_Iter&>())) && 
+    is_nothrow_assignable<_Iter&, _Iter>::value && 
+    noexcept(declval<_Iter>() == declval<_Iter>()) && 
+    noexcept(*declval<_Iter>())
+)) {};
+
+template <class _Iter> 
+struct __libcpp_string_gets_noexcept_iterator_impl<_Iter, false> : public false_type {};
+#endif
+
+
+template <class _Iter>
+struct __libcpp_string_gets_noexcept_iterator
+    : public _LIBCPP_BOOL_CONSTANT(__libcpp_is_trivial_iterator<_Iter>::value || __libcpp_string_gets_noexcept_iterator_impl<_Iter>::value) {};
+
+#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
 
 template <class _CharT, size_t = sizeof(_CharT)>
 struct __padding
@@ -1198,7 +1238,7 @@ struct __padding<_CharT, 1>
 {
 };
 
-#endif  // _LIBCPP_ALTERNATE_STRING_LAYOUT
+#endif  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
 
 template<class _CharT, class _Traits, class _Allocator>
 class _LIBCPP_TYPE_VIS_ONLY basic_string
@@ -1234,7 +1274,7 @@ public:
 
 private:
 
-#ifdef _LIBCPP_ALTERNATE_STRING_LAYOUT
+#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
 
     struct __long
     {
@@ -1294,7 +1334,7 @@ private:
         value_type __data_[__min_cap];
     };
 
-#endif  // _LIBCPP_ALTERNATE_STRING_LAYOUT
+#endif  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
 
     union __ulx{__long __lx; __short __lxx;};
 
@@ -1377,8 +1417,7 @@ public:
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
     _LIBCPP_INLINE_VISIBILITY
     basic_string& operator=(basic_string&& __str)
-        _NOEXCEPT_(__alloc_traits::propagate_on_container_move_assignment::value &&
-                   is_nothrow_move_assignable<allocator_type>::value);
+        _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value));
 #endif
     _LIBCPP_INLINE_VISIBILITY basic_string& operator=(const value_type* __s) {return assign(__s);}
     basic_string& operator=(value_type __c);
@@ -1480,15 +1519,16 @@ public:
     template<class _InputIterator>
         typename enable_if
         <
-             __is_input_iterator  <_InputIterator>::value &&
-            !__is_forward_iterator<_InputIterator>::value,
+            __is_exactly_input_iterator<_InputIterator>::value
+                || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
             basic_string&
         >::type
         append(_InputIterator __first, _InputIterator __last);
     template<class _ForwardIterator>
         typename enable_if
         <
-            __is_forward_iterator<_ForwardIterator>::value,
+            __is_forward_iterator<_ForwardIterator>::value
+                && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
             basic_string&
         >::type
         append(_ForwardIterator __first, _ForwardIterator __last);
@@ -1510,6 +1550,7 @@ public:
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
     _LIBCPP_INLINE_VISIBILITY
     basic_string& assign(basic_string&& str)
+        _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
         {*this = _VSTD::move(str); return *this;}
 #endif
     basic_string& assign(const basic_string& __str, size_type __pos, size_type __n=npos);
@@ -1519,15 +1560,16 @@ public:
     template<class _InputIterator>
         typename enable_if
         <
-             __is_input_iterator  <_InputIterator>::value &&
-            !__is_forward_iterator<_InputIterator>::value,
+           __is_exactly_input_iterator<_InputIterator>::value
+                || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
             basic_string&
         >::type
         assign(_InputIterator __first, _InputIterator __last);
     template<class _ForwardIterator>
         typename enable_if
         <
-            __is_forward_iterator<_ForwardIterator>::value,
+            __is_forward_iterator<_ForwardIterator>::value
+                 && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
             basic_string&
         >::type
         assign(_ForwardIterator __first, _ForwardIterator __last);
@@ -1548,15 +1590,16 @@ public:
     template<class _InputIterator>
         typename enable_if
         <
-             __is_input_iterator  <_InputIterator>::value &&
-            !__is_forward_iterator<_InputIterator>::value,
+           __is_exactly_input_iterator<_InputIterator>::value
+                || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
             iterator
         >::type
         insert(const_iterator __pos, _InputIterator __first, _InputIterator __last);
     template<class _ForwardIterator>
         typename enable_if
         <
-            __is_forward_iterator<_ForwardIterator>::value,
+            __is_forward_iterator<_ForwardIterator>::value
+                 && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
             iterator
         >::type
         insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last);
@@ -1698,7 +1741,7 @@ private:
     const allocator_type& __alloc() const _NOEXCEPT
         {return __r_.second();}
 
-#ifdef _LIBCPP_ALTERNATE_STRING_LAYOUT
+#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
 
     _LIBCPP_INLINE_VISIBILITY
     void __set_short_size(size_type __s) _NOEXCEPT
@@ -1716,7 +1759,7 @@ private:
         {return __r_.first().__s.__size_;}
 #   endif
 
-#else  // _LIBCPP_ALTERNATE_STRING_LAYOUT
+#else  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
 
     _LIBCPP_INLINE_VISIBILITY
     void __set_short_size(size_type __s) _NOEXCEPT
@@ -1734,7 +1777,7 @@ private:
         {return __r_.first().__s.__size_ >> 1;}
 #   endif
 
-#endif  // _LIBCPP_ALTERNATE_STRING_LAYOUT
+#endif  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
 
     _LIBCPP_INLINE_VISIBILITY
     void __set_long_size(size_type __s) _NOEXCEPT
@@ -1801,8 +1844,7 @@ private:
     template <class _InputIterator>
     typename enable_if
     <
-         __is_input_iterator  <_InputIterator>::value &&
-        !__is_forward_iterator<_InputIterator>::value,
+        __is_exactly_input_iterator<_InputIterator>::value,
         void
     >::type
     __init(_InputIterator __first, _InputIterator __last);
@@ -1846,11 +1888,16 @@ private:
 
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
     _LIBCPP_INLINE_VISIBILITY
-    void __move_assign(basic_string& __str, false_type);
+    void __move_assign(basic_string& __str, false_type)
+        _NOEXCEPT_(__alloc_traits::is_always_equal::value);
     _LIBCPP_INLINE_VISIBILITY
     void __move_assign(basic_string& __str, true_type)
+#if _LIBCPP_STD_VER > 14
+        _NOEXCEPT;
+#else
         _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
 #endif
+#endif
 
     _LIBCPP_INLINE_VISIBILITY
     void
@@ -2174,8 +2221,7 @@ template <class _CharT, class _Traits, class _Allocator>
 template <class _InputIterator>
 typename enable_if
 <
-     __is_input_iterator  <_InputIterator>::value &&
-    !__is_forward_iterator<_InputIterator>::value,
+    __is_exactly_input_iterator<_InputIterator>::value,
     void
 >::type
 basic_string<_CharT, _Traits, _Allocator>::__init(_InputIterator __first, _InputIterator __last)
@@ -2431,6 +2477,7 @@ template <class _CharT, class _Traits, class _Allocator>
 inline _LIBCPP_INLINE_VISIBILITY
 void
 basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, false_type)
+    _NOEXCEPT_(__alloc_traits::is_always_equal::value)
 {
     if (__alloc() != __str.__alloc())
         assign(__str);
@@ -2442,7 +2489,11 @@ template <class _CharT, class _Traits, class _Allocator>
 inline _LIBCPP_INLINE_VISIBILITY
 void
 basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, true_type)
+#if _LIBCPP_STD_VER > 14
+    _NOEXCEPT
+#else
     _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
+#endif
 {
     clear();
     shrink_to_fit();
@@ -2455,8 +2506,7 @@ template <class _CharT, class _Traits, class _Allocator>
 inline _LIBCPP_INLINE_VISIBILITY
 basic_string<_CharT, _Traits, _Allocator>&
 basic_string<_CharT, _Traits, _Allocator>::operator=(basic_string&& __str)
-    _NOEXCEPT_(__alloc_traits::propagate_on_container_move_assignment::value &&
-               is_nothrow_move_assignable<allocator_type>::value)
+    _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
 {
     __move_assign(__str, integral_constant<bool,
           __alloc_traits::propagate_on_container_move_assignment::value>());
@@ -2469,15 +2519,14 @@ template <class _CharT, class _Traits, class _Allocator>
 template<class _InputIterator>
 typename enable_if
 <
-     __is_input_iterator  <_InputIterator>::value &&
-    !__is_forward_iterator<_InputIterator>::value,
+     __is_exactly_input_iterator <_InputIterator>::value
+          || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
     basic_string<_CharT, _Traits, _Allocator>&
 >::type
 basic_string<_CharT, _Traits, _Allocator>::assign(_InputIterator __first, _InputIterator __last)
 {
-    clear();
-    for (; __first != __last; ++__first)
-        push_back(*__first);
+    basic_string __temp(__first, __last, __alloc());
+    assign(__temp.data(), __temp.size());
     return *this;
 }
 
@@ -2485,7 +2534,8 @@ template <class _CharT, class _Traits, class _Allocator>
 template<class _ForwardIterator>
 typename enable_if
 <
-    __is_forward_iterator<_ForwardIterator>::value,
+    __is_forward_iterator<_ForwardIterator>::value
+         && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
     basic_string<_CharT, _Traits, _Allocator>&
 >::type
 basic_string<_CharT, _Traits, _Allocator>::assign(_ForwardIterator __first, _ForwardIterator __last)
@@ -2618,14 +2668,14 @@ template <class _CharT, class _Traits, class _Allocator>
 template<class _InputIterator>
 typename enable_if
 <
-     __is_input_iterator  <_InputIterator>::value &&
-    !__is_forward_iterator<_InputIterator>::value,
+    __is_exactly_input_iterator<_InputIterator>::value
+             || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
     basic_string<_CharT, _Traits, _Allocator>&
 >::type
 basic_string<_CharT, _Traits, _Allocator>::append(_InputIterator __first, _InputIterator __last)
 {
-    for (; __first != __last; ++__first)
-        push_back(*__first);
+	basic_string __temp (__first, __last, __alloc());
+	append(__temp.data(), __temp.size());
     return *this;
 }
 
@@ -2633,7 +2683,8 @@ template <class _CharT, class _Traits, class _Allocator>
 template<class _ForwardIterator>
 typename enable_if
 <
-    __is_forward_iterator<_ForwardIterator>::value,
+    __is_forward_iterator<_ForwardIterator>::value
+          && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
     basic_string<_CharT, _Traits, _Allocator>&
 >::type
 basic_string<_CharT, _Traits, _Allocator>::append(_ForwardIterator __first, _ForwardIterator __last)
@@ -2749,9 +2800,9 @@ template <class _CharT, class _Traits, class _Allocator>
 template<class _InputIterator>
 typename enable_if
 <
-     __is_input_iterator  <_InputIterator>::value &&
-    !__is_forward_iterator<_InputIterator>::value,
-    typename basic_string<_CharT, _Traits, _Allocator>::iterator
+   __is_exactly_input_iterator<_InputIterator>::value
+        || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
+   typename basic_string<_CharT, _Traits, _Allocator>::iterator
 >::type
 basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _InputIterator __first, _InputIterator __last)
 {
@@ -2760,24 +2811,16 @@ basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _InputIt
         "string::insert(iterator, range) called with an iterator not"
         " referring to this string");
 #endif
-    size_type __old_sz = size();
-    difference_type __ip = __pos - begin();
-    for (; __first != __last; ++__first)
-        push_back(*__first);
-    pointer __p = __get_pointer();
-    _VSTD::rotate(__p + __ip, __p + __old_sz, __p + size());
-#if _LIBCPP_DEBUG_LEVEL >= 2
-    return iterator(this, __p + __ip);
-#else
-    return iterator(__p + __ip);
-#endif
+    basic_string __temp(__first, __last, __alloc());
+    return insert(__pos, __temp.data(), __temp.data() + __temp.size());
 }
 
 template <class _CharT, class _Traits, class _Allocator>
 template<class _ForwardIterator>
 typename enable_if
 <
-    __is_forward_iterator<_ForwardIterator>::value,
+    __is_forward_iterator<_ForwardIterator>::value
+        && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
     typename basic_string<_CharT, _Traits, _Allocator>::iterator
 >::type
 basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last)
@@ -2980,22 +3023,8 @@ typename enable_if
 basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2,
                                                    _InputIterator __j1, _InputIterator __j2)
 {
-    for (; true; ++__i1, ++__j1)
-    {
-        if (__i1 == __i2)
-        {
-            if (__j1 != __j2)
-                insert(__i1, __j1, __j2);
-            break;
-        }
-        if (__j1 == __j2)
-        {
-            erase(__i1, __i2);
-            break;
-        }
-        traits_type::assign(const_cast<value_type&>(*__i1), *__j1);
-    }
-    return *this;
+    basic_string __temp(__j1, __j2, __alloc());
+    return this->replace(__i1, __i2, __temp);
 }
 
 template <class _CharT, class _Traits, class _Allocator>
@@ -3788,7 +3817,11 @@ bool
 operator==(const _CharT* __lhs,
            const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
 {
-    return __rhs.compare(__lhs) == 0;
+    typedef basic_string<_CharT, _Traits, _Allocator> _String;
+    _LIBCPP_ASSERT(__lhs != nullptr, "operator==(char*, basic_string): received nullptr");
+    size_t __lhs_len = _Traits::length(__lhs);
+    if (__lhs_len != __rhs.size()) return false;
+    return __rhs.compare(0, _String::npos, __lhs, __lhs_len) == 0;
 }
 
 template<class _CharT, class _Traits, class _Allocator>
@@ -3797,7 +3830,11 @@ bool
 operator==(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
            const _CharT* __rhs) _NOEXCEPT
 {
-    return __lhs.compare(__rhs) == 0;
+    typedef basic_string<_CharT, _Traits, _Allocator> _String;
+    _LIBCPP_ASSERT(__rhs != nullptr, "operator==(basic_string, char*): received nullptr");
+    size_t __rhs_len = _Traits::length(__rhs);
+    if (__rhs_len != __lhs.size()) return false;
+    return __lhs.compare(0, _String::npos, __rhs, __rhs_len) == 0;
 }
 
 // operator!=