Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -565,6 +565,7 @@
 if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
     add_compile_flags_if_supported(
         -Wno-user-defined-literals
+        -Wzero-as-null-pointer-constant
         -Wno-covered-switch-default)
     if (LIBCXX_TARGETING_CLANG_CL)
       add_compile_flags_if_supported(
@@ -575,7 +576,6 @@
         -Wno-reserved-id-macro
         -Wno-gnu-include-next
         -Wno-gcc-compat # For ignoring "'diagnose_if' is a clang extension" warnings
-        -Wno-zero-as-null-pointer-constant # FIXME: Remove this and fix all occurrences.
         -Wno-deprecated-dynamic-exception-spec # For auto_ptr
         -Wno-sign-conversion
         -Wno-old-style-cast
Index: include/__functional_base
===================================================================
--- include/__functional_base
+++ include/__functional_base
@@ -39,7 +39,7 @@
     template <class _Up> static __two __test(...);
     template <class _Up> static char __test(typename _Up::result_type* = 0);
 public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+    static const bool value = sizeof(__test<_Tp>(nullptr)) == 1;
 };
 
 #if _LIBCPP_STD_VER > 11
@@ -576,7 +576,7 @@
     template <class _Up> static __two __test(...);
     template <class _Up> static char __test(typename _Up::allocator_type* = 0);
 public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+    static const bool value = sizeof(__test<_Tp>(nullptr)) == 1;
 };
 
 template <class _Tp, class _Alloc, bool = __has_allocator_type<_Tp>::value>
Index: include/__locale
===================================================================
--- include/__locale
+++ include/__locale
@@ -604,7 +604,7 @@
 public:
     typedef char char_type;
 
-    explicit ctype(const mask* __tab = 0, bool __del = false, size_t __refs = 0);
+    explicit ctype(const mask* __tab = nullptr, bool __del = false, size_t __refs = 0);
 
     _LIBCPP_INLINE_VISIBILITY
     bool is(mask __m, char_type __c) const
Index: include/__sso_allocator
===================================================================
--- include/__sso_allocator
+++ include/__sso_allocator
@@ -47,7 +47,7 @@
 private:
     __sso_allocator& operator=(const __sso_allocator&);
 public:
-    _LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, typename __sso_allocator<void, _Np>::const_pointer = 0)
+    _LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, typename __sso_allocator<void, _Np>::const_pointer = nullptr)
     {
         if (!__allocated_ && __n <= _Np)
         {
Index: include/__string
===================================================================
--- include/__string
+++ include/__string
@@ -562,7 +562,7 @@
             return __s;
         ++__s;
     }
-    return 0;
+    return nullptr;
 }
 
 inline
@@ -681,7 +681,7 @@
             return __s;
         ++__s;
     }
-    return 0;
+    return nullptr;
 }
 
 inline
@@ -738,7 +738,7 @@
     if (__pos >= __sz)
         return __npos;
     const _CharT* __r = _Traits::find(__p + __pos, __sz - __pos, __c);
-    if (__r == 0)
+    if (__r == nullptr)
         return __npos;
     return static_cast<_SizeT>(__r - __p);
 }
@@ -767,7 +767,7 @@
 
     // Find __f2 the first byte matching in __first1.
     __first1 = _Traits::find(__first1, __len1 - __len2 + 1, __f2);
-    if (__first1 == 0)
+    if (__first1 == nullptr)
       return __last1;
 
     // It is faster to compare from the first byte of __first1 even if we
@@ -890,7 +890,7 @@
     {
         const _CharT* __pe = __p + __sz;
         for (const _CharT* __ps = __p + __pos; __ps != __pe; ++__ps)
-            if (_Traits::find(__s, __n, *__ps) == 0)
+            if (_Traits::find(__s, __n, *__ps) == nullptr)
                 return static_cast<_SizeT>(__ps - __p);
     }
     return __npos;
@@ -924,7 +924,7 @@
     else
         __pos = __sz;
     for (const _CharT* __ps = __p + __pos; __ps != __p;)
-        if (_Traits::find(__s, __n, *--__ps) == 0)
+        if (_Traits::find(__s, __n, *--__ps) == nullptr)
             return static_cast<_SizeT>(__ps - __p);
     return __npos;
 }
Index: include/__threading_support
===================================================================
--- include/__threading_support
+++ include/__threading_support
@@ -318,13 +318,13 @@
 
 // Thread
 bool __libcpp_thread_isnull(const __libcpp_thread_t *__t) {
-  return *__t == 0;
+  return *__t == nullptr;
 }
 
 int __libcpp_thread_create(__libcpp_thread_t *__t, void *(*__func)(void *),
                            void *__arg)
 {
-  return pthread_create(__t, 0, __func, __arg);
+  return pthread_create(__t, nullptr, __func, __arg);
 }
 
 __libcpp_thread_id __libcpp_thread_get_current_id()
@@ -339,7 +339,7 @@
 
 int __libcpp_thread_join(__libcpp_thread_t *__t)
 {
-  return pthread_join(*__t, 0);
+  return pthread_join(*__t, nullptr);
 }
 
 int __libcpp_thread_detach(__libcpp_thread_t *__t)
Index: include/algorithm
===================================================================
--- include/algorithm
+++ include/algorithm
@@ -3875,7 +3875,7 @@
         unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
         value_type* __last2 = __first2;
         ::new(__last2) value_type(_VSTD::move(*__first1));
-        __d.__incr((value_type*)0);
+        __d.__incr((value_type*)nullptr);
         for (++__last2; ++__first1 != __last1; ++__last2)
         {
             value_type* __j2 = __last2;
@@ -3883,7 +3883,7 @@
             if (__comp(*__first1, *--__i2))
             {
                 ::new(__j2) value_type(_VSTD::move(*__i2));
-                __d.__incr((value_type*)0);
+                __d.__incr((value_type*)nullptr);
                 for (--__j2; __i2 != __first2 && __comp(*__first1,  *--__i2); --__j2)
                     *__j2 = _VSTD::move(*__i2);
                 *__j2 = _VSTD::move(*__first1);
@@ -3891,7 +3891,7 @@
             else
             {
                 ::new(__j2) value_type(_VSTD::move(*__first1));
-                __d.__incr((value_type*)0);
+                __d.__incr((value_type*)nullptr);
             }
         }
         __h.release();
@@ -4432,14 +4432,14 @@
     if (__len1 <= __len2)
     {
         value_type* __p = __buff;
-        for (_BidirectionalIterator __i = __first; __i != __middle; __d.__incr((value_type*)0), (void) ++__i, ++__p)
+        for (_BidirectionalIterator __i = __first; __i != __middle; __d.__incr((value_type*)nullptr), (void) ++__i, ++__p)
             ::new(__p) value_type(_VSTD::move(*__i));
         __half_inplace_merge(__buff, __p, __middle, __last, __first, __comp);
     }
     else
     {
         value_type* __p = __buff;
-        for (_BidirectionalIterator __i = __middle; __i != __last; __d.__incr((value_type*)0), (void) ++__i, ++__p)
+        for (_BidirectionalIterator __i = __middle; __i != __last; __d.__incr((value_type*)nullptr), (void) ++__i, ++__p)
             ::new(__p) value_type(_VSTD::move(*__i));
         typedef reverse_iterator<_BidirectionalIterator> _RBi;
         typedef reverse_iterator<value_type*> _Rv;
@@ -4579,14 +4579,14 @@
     {
         if (__first1 == __last1)
         {
-            for (; __first2 != __last2; ++__first2, ++__result, __d.__incr((value_type*)0))
+            for (; __first2 != __last2; ++__first2, ++__result, __d.__incr((value_type*)nullptr))
                 ::new (__result) value_type(_VSTD::move(*__first2));
             __h.release();
             return;
         }
         if (__first2 == __last2)
         {
-            for (; __first1 != __last1; ++__first1, ++__result, __d.__incr((value_type*)0))
+            for (; __first1 != __last1; ++__first1, ++__result, __d.__incr((value_type*)nullptr))
                 ::new (__result) value_type(_VSTD::move(*__first1));
             __h.release();
             return;
@@ -4594,13 +4594,13 @@
         if (__comp(*__first2, *__first1))
         {
             ::new (__result) value_type(_VSTD::move(*__first2));
-            __d.__incr((value_type*)0);
+            __d.__incr((value_type*)nullptr);
             ++__first2;
         }
         else
         {
             ::new (__result) value_type(_VSTD::move(*__first1));
-            __d.__incr((value_type*)0);
+            __d.__incr((value_type*)nullptr);
             ++__first1;
         }
     }
@@ -4661,14 +4661,14 @@
         if (__comp(*--__last1, *__first1))
         {
             ::new(__first2) value_type(_VSTD::move(*__last1));
-            __d.__incr((value_type*)0);
+            __d.__incr((value_type*)nullptr);
             ++__first2;
             ::new(__first2) value_type(_VSTD::move(*__first1));
         }
         else
         {
             ::new(__first2) value_type(_VSTD::move(*__first1));
-            __d.__incr((value_type*)0);
+            __d.__incr((value_type*)nullptr);
             ++__first2;
             ::new(__first2) value_type(_VSTD::move(*__last1));
         }
@@ -4723,9 +4723,9 @@
         __destruct_n __d(0);
         unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
         __stable_sort_move<_Compare>(__first, __m, __comp, __l2, __buff);
-        __d.__set(__l2, (value_type*)0);
+        __d.__set(__l2, (value_type*)nullptr);
         __stable_sort_move<_Compare>(__m, __last, __comp, __len - __l2, __buff + __l2);
-        __d.__set(__len, (value_type*)0);
+        __d.__set(__len, (value_type*)nullptr);
         __merge_move_assign<_Compare>(__buff, __buff + __l2, __buff + __l2, __buff + __len, __first, __comp);
 //         __merge<_Compare>(move_iterator<value_type*>(__buff),
 //                           move_iterator<value_type*>(__buff + __l2),
Index: include/bitset
===================================================================
--- include/bitset
+++ include/bitset
@@ -625,13 +625,13 @@
     explicit _LIBCPP_CONSTEXPR __bitset(unsigned long long) _NOEXCEPT;
 
     _LIBCPP_INLINE_VISIBILITY reference __make_ref(size_t) _NOEXCEPT
-        {return reference(0, 1);}
+        {return reference(nullptr, 1);}
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR const_reference __make_ref(size_t) const _NOEXCEPT
-        {return const_reference(0, 1);}
+        {return const_reference(nullptr, 1);}
     _LIBCPP_INLINE_VISIBILITY iterator __make_iter(size_t) _NOEXCEPT
-        {return iterator(0, 0);}
+        {return iterator(nullptr, 0);}
     _LIBCPP_INLINE_VISIBILITY const_iterator __make_iter(size_t) const _NOEXCEPT
-        {return const_iterator(0, 0);}
+        {return const_iterator(nullptr, 0);}
 
     _LIBCPP_INLINE_VISIBILITY void operator&=(const __bitset&) _NOEXCEPT {}
     _LIBCPP_INLINE_VISIBILITY void operator|=(const __bitset&) _NOEXCEPT {}
Index: include/chrono
===================================================================
--- include/chrono
+++ include/chrono
@@ -1046,7 +1046,7 @@
                is_convertible<_Rep2, rep>::value &&
                (treat_as_floating_point<rep>::value ||
                !treat_as_floating_point<_Rep2>::value)
-            >::type* = 0)
+            >::type* = nullptr)
                 : __rep_(__r) {}
 
     // conversions
@@ -1059,7 +1059,7 @@
                 treat_as_floating_point<rep>::value ||
                 (__no_overflow<_Period2, period>::type::den == 1 &&
                  !treat_as_floating_point<_Rep2>::value))
-            >::type* = 0)
+            >::type* = nullptr)
                 : __rep_(_VSTD::chrono::duration_cast<duration>(__d).count()) {}
 
     // observer
@@ -1345,7 +1345,7 @@
         typename enable_if
         <
             is_convertible<_Duration2, duration>::value
-        >::type* = 0)
+        >::type* = nullptr)
             : __d_(t.time_since_epoch()) {}
 
     // observer
Index: include/deque
===================================================================
--- include/deque
+++ include/deque
@@ -1070,7 +1070,7 @@
 __deque_base<_Tp, _Allocator>::begin() _NOEXCEPT
 {
     __map_pointer __mp = __map_.begin() + __start_ / __block_size;
-    return iterator(__mp, __map_.empty() ? 0 : *__mp + __start_ % __block_size);
+    return iterator(__mp, __map_.empty() ? nullptr : *__mp + __start_ % __block_size);
 }
 
 template <class _Tp, class _Allocator>
@@ -1078,7 +1078,7 @@
 __deque_base<_Tp, _Allocator>::begin() const _NOEXCEPT
 {
     __map_const_pointer __mp = static_cast<__map_const_pointer>(__map_.begin() + __start_ / __block_size);
-    return const_iterator(__mp, __map_.empty() ? 0 : *__mp + __start_ % __block_size);
+    return const_iterator(__mp, __map_.empty() ? nullptr : *__mp + __start_ % __block_size);
 }
 
 template <class _Tp, class _Allocator>
@@ -1087,7 +1087,7 @@
 {
     size_type __p = size() + __start_;
     __map_pointer __mp = __map_.begin() + __p / __block_size;
-    return iterator(__mp, __map_.empty() ? 0 : *__mp + __p % __block_size);
+    return iterator(__mp, __map_.empty() ? nullptr : *__mp + __p % __block_size);
 }
 
 template <class _Tp, class _Allocator>
Index: include/fstream
===================================================================
--- include/fstream
+++ include/fstream
@@ -286,13 +286,13 @@
 
 template <class _CharT, class _Traits>
 basic_filebuf<_CharT, _Traits>::basic_filebuf()
-    : __extbuf_(0),
-      __extbufnext_(0),
-      __extbufend_(0),
+    : __extbuf_(nullptr),
+      __extbufnext_(nullptr),
+      __extbufend_(nullptr),
       __ebs_(0),
-      __intbuf_(0),
+      __intbuf_(nullptr),
       __ibs_(0),
-      __file_(0),
+      __file_(nullptr),
       __cv_(nullptr),
       __st_(),
       __st_last_(),
@@ -307,7 +307,7 @@
         __cv_ = &use_facet<codecvt<char_type, char, state_type> >(this->getloc());
         __always_noconv_ = __cv_->always_noconv();
     }
-    setbuf(0, 4096);
+    setbuf(nullptr, 4096);
 }
 
 #ifndef _LIBCPP_CXX03_LANG
@@ -359,13 +359,13 @@
                        (char_type*)__extbuf_ + (__rhs.gptr() - __rhs.eback()),
                        (char_type*)__extbuf_ + (__rhs.egptr() - __rhs.eback()));
     }
-    __rhs.__extbuf_ = 0;
-    __rhs.__extbufnext_ = 0;
-    __rhs.__extbufend_ = 0;
+    __rhs.__extbuf_ = nullptr;
+    __rhs.__extbufnext_ = nullptr;
+    __rhs.__extbufend_ = nullptr;
     __rhs.__ebs_ = 0;
     __rhs.__intbuf_ = 0;
     __rhs.__ibs_ = 0;
-    __rhs.__file_ = 0;
+    __rhs.__file_ = nullptr;
     __rhs.__st_ = state_type();
     __rhs.__st_last_ = state_type();
     __rhs.__om_ = 0;
@@ -499,7 +499,7 @@
 bool
 basic_filebuf<_CharT, _Traits>::is_open() const
 {
-    return __file_ != 0;
+    return __file_ != nullptr;
 }
 
 template <class _CharT, class _Traits>
@@ -547,8 +547,8 @@
 basic_filebuf<_CharT, _Traits>*
 basic_filebuf<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode)
 {
-    basic_filebuf<_CharT, _Traits>* __rt = 0;
-    if (__file_ == 0)
+    basic_filebuf<_CharT, _Traits>* __rt = nullptr;
+    if (__file_ == nullptr)
     {
       if (const char* __mdstr = __make_mdstring(__mode)) {
         __rt = this;
@@ -558,12 +558,12 @@
           if (__mode & ios_base::ate) {
             if (fseek(__file_, 0, SEEK_END)) {
               fclose(__file_);
-              __file_ = 0;
-              __rt = 0;
+              __file_ = nullptr;
+              __rt = nullptr;
             }
           }
         } else
-          __rt = 0;
+          __rt = nullptr;
       }
     }
     return __rt;
@@ -572,8 +572,8 @@
 template <class _CharT, class _Traits>
 _LIBCPP_INLINE_VISIBILITY basic_filebuf<_CharT, _Traits>*
 basic_filebuf<_CharT, _Traits>::__open(int __fd, ios_base::openmode __mode) {
-  basic_filebuf<_CharT, _Traits>* __rt = 0;
-  if (__file_ == 0) {
+  basic_filebuf<_CharT, _Traits>* __rt = nullptr;
+  if (__file_ == nullptr) {
     if (const char* __mdstr = __make_mdstring(__mode)) {
       __rt = this;
       __file_ = fdopen(__fd, __mdstr);
@@ -582,12 +582,12 @@
         if (__mode & ios_base::ate) {
           if (fseek(__file_, 0, SEEK_END)) {
             fclose(__file_);
-            __file_ = 0;
-            __rt = 0;
+            __file_ = nullptr;
+            __rt = nullptr;
           }
         }
       } else
-        __rt = 0;
+        __rt = nullptr;
     }
   }
   return __rt;
@@ -600,8 +600,8 @@
 basic_filebuf<_CharT, _Traits>*
 basic_filebuf<_CharT, _Traits>::open(const wchar_t* __s, ios_base::openmode __mode)
 {
-    basic_filebuf<_CharT, _Traits>* __rt = 0;
-    if (__file_ == 0)
+    basic_filebuf<_CharT, _Traits>* __rt = nullptr;
+    if (__file_ == nullptr)
     {
         __rt = this;
         const wchar_t* __mdstr;
@@ -650,7 +650,7 @@
             __mdstr = L"a+b";
             break;
         default:
-            __rt = 0;
+            __rt = nullptr;
             break;
         }
         if (__rt)
@@ -664,13 +664,13 @@
                     if (fseek(__file_, 0, SEEK_END))
                     {
                         fclose(__file_);
-                        __file_ = 0;
-                        __rt = 0;
+                        __file_ = nullptr;
+                        __rt = nullptr;
                     }
                 }
             }
             else
-                __rt = 0;
+                __rt = nullptr;
         }
     }
     return __rt;
@@ -690,18 +690,18 @@
 basic_filebuf<_CharT, _Traits>*
 basic_filebuf<_CharT, _Traits>::close()
 {
-    basic_filebuf<_CharT, _Traits>* __rt = 0;
+    basic_filebuf<_CharT, _Traits>* __rt = nullptr;
     if (__file_)
     {
         __rt = this;
         unique_ptr<FILE, int(*)(FILE*)> __h(__file_, fclose);
         if (sync())
-            __rt = 0;
+            __rt = nullptr;
         if (fclose(__h.release()) == 0)
-            __file_ = 0;
+            __file_ = nullptr;
         else
-            __rt = 0;
-        setbuf(0, 0);
+            __rt = nullptr;
+        setbuf(nullptr, 0);
     }
     return __rt;
 }
@@ -710,11 +710,11 @@
 typename basic_filebuf<_CharT, _Traits>::int_type
 basic_filebuf<_CharT, _Traits>::underflow()
 {
-    if (__file_ == 0)
+    if (__file_ == nullptr)
         return traits_type::eof();
     bool __initial = __read_mode();
     char_type __1buf;
-    if (this->gptr() == 0)
+    if (this->gptr() == nullptr)
         this->setg(&__1buf, &__1buf+1, &__1buf+1);
     const size_t __unget_sz = __initial ? 0 : min<size_t>((this->egptr() - this->eback()) / 2, 4);
     int_type __c = traits_type::eof();
@@ -772,7 +772,7 @@
     else
         __c = traits_type::to_int_type(*this->gptr());
     if (this->eback() == &__1buf)
-        this->setg(0, 0, 0);
+        this->setg(nullptr, nullptr, nullptr);
     return __c;
 }
 
@@ -802,7 +802,7 @@
 typename basic_filebuf<_CharT, _Traits>::int_type
 basic_filebuf<_CharT, _Traits>::overflow(int_type __c)
 {
-    if (__file_ == 0)
+    if (__file_ == nullptr)
         return traits_type::eof();
     __write_mode();
     char_type __1buf;
@@ -810,7 +810,7 @@
     char_type* __epb_save = this->epptr();
     if (!traits_type::eq_int_type(__c, traits_type::eof()))
     {
-        if (this->pptr() == 0)
+        if (this->pptr() == nullptr)
             this->setp(&__1buf, &__1buf+1);
         *this->pptr() = traits_type::to_char_type(__c);
         this->pbump(1);
@@ -867,8 +867,8 @@
 basic_streambuf<_CharT, _Traits>*
 basic_filebuf<_CharT, _Traits>::setbuf(char_type* __s, streamsize __n)
 {
-    this->setg(0, 0, 0);
-    this->setp(0, 0);
+    this->setg(nullptr, nullptr, nullptr);
+    this->setp(nullptr, nullptr);
     if (__owns_eb_)
         delete [] __extbuf_;
     if (__owns_ib_)
@@ -910,7 +910,7 @@
     else
     {
         __ibs_ = 0;
-        __intbuf_ = 0;
+        __intbuf_ = nullptr;
         __owns_ib_ = false;
     }
     return this;
@@ -925,7 +925,7 @@
         __throw_bad_cast();
 
     int __width = __cv_->encoding();
-    if (__file_ == 0 || (__width <= 0 && __off != 0) || sync())
+    if (__file_ == nullptr || (__width <= 0 && __off != 0) || sync())
         return pos_type(off_type(-1));
     // __width > 0 || __off == 0
     int __whence;
@@ -960,7 +960,7 @@
 typename basic_filebuf<_CharT, _Traits>::pos_type
 basic_filebuf<_CharT, _Traits>::seekpos(pos_type __sp, ios_base::openmode)
 {
-    if (__file_ == 0 || sync())
+    if (__file_ == nullptr || sync())
         return pos_type(off_type(-1));
 #if defined(_LIBCPP_HAS_NO_OFF_T_FUNCTIONS)
     if (fseek(__file_, __sp, SEEK_SET))
@@ -977,7 +977,7 @@
 int
 basic_filebuf<_CharT, _Traits>::sync()
 {
-    if (__file_ == 0)
+    if (__file_ == nullptr)
         return 0;
     if (!__cv_)
         __throw_bad_cast();
@@ -1036,7 +1036,7 @@
         if (__update_st)
             __st_ = __state;
         __extbufnext_ = __extbufend_ = __extbuf_;
-        this->setg(0, 0, 0);
+        this->setg(nullptr, nullptr, nullptr);
         __cm_ = 0;
     }
     return 0;
@@ -1052,8 +1052,8 @@
     __always_noconv_ = __cv_->always_noconv();
     if (__old_anc != __always_noconv_)
     {
-        this->setg(0, 0, 0);
-        this->setp(0, 0);
+        this->setg(nullptr, nullptr, nullptr);
+        this->setp(nullptr, nullptr);
         // invariant, char_type is char, else we couldn't get here
         if (__always_noconv_)  // need to dump __intbuf_
         {
@@ -1063,7 +1063,7 @@
             __ebs_ = __ibs_;
             __extbuf_ = (char*)__intbuf_;
             __ibs_ = 0;
-            __intbuf_ = 0;
+            __intbuf_ = nullptr;
             __owns_ib_ = false;
         }
         else  // need to obtain an __intbuf_.
@@ -1092,7 +1092,7 @@
 {
     if (!(__cm_ & ios_base::in))
     {
-        this->setp(0, 0);
+        this->setp(nullptr, nullptr);
         if (__always_noconv_)
             this->setg((char_type*)__extbuf_,
                        (char_type*)__extbuf_ + __ebs_,
@@ -1111,7 +1111,7 @@
 {
     if (!(__cm_ & ios_base::out))
     {
-        this->setg(0, 0, 0);
+        this->setg(nullptr, nullptr, nullptr);
         if (__ebs_ > sizeof(__extbuf_min_))
         {
             if (__always_noconv_)
@@ -1121,7 +1121,7 @@
                 this->setp(__intbuf_, __intbuf_ + (__ibs_ - 1));
         }
         else
-            this->setp(0, 0);
+            this->setp(nullptr, nullptr);
         __cm_ = ios_base::out;
     }
 }
@@ -1207,7 +1207,7 @@
 basic_ifstream<_CharT, _Traits>::basic_ifstream(const char* __s, ios_base::openmode __mode)
     : basic_istream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode | ios_base::in) == 0)
+    if (__sb_.open(__s, __mode | ios_base::in) == nullptr)
         this->setstate(ios_base::failbit);
 }
 
@@ -1217,7 +1217,7 @@
 basic_ifstream<_CharT, _Traits>::basic_ifstream(const wchar_t* __s, ios_base::openmode __mode)
     : basic_istream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode | ios_base::in) == 0)
+    if (__sb_.open(__s, __mode | ios_base::in) == nullptr)
         this->setstate(ios_base::failbit);
 }
 #endif
@@ -1227,7 +1227,7 @@
 basic_ifstream<_CharT, _Traits>::basic_ifstream(const string& __s, ios_base::openmode __mode)
     : basic_istream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode | ios_base::in) == 0)
+    if (__sb_.open(__s, __mode | ios_base::in) == nullptr)
         this->setstate(ios_base::failbit);
 }
 #endif
@@ -1420,7 +1420,7 @@
 basic_ofstream<_CharT, _Traits>::basic_ofstream(const char* __s, ios_base::openmode __mode)
     : basic_ostream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode | ios_base::out) == 0)
+    if (__sb_.open(__s, __mode | ios_base::out) == nullptr)
         this->setstate(ios_base::failbit);
 }
 
@@ -1430,7 +1430,7 @@
 basic_ofstream<_CharT, _Traits>::basic_ofstream(const wchar_t* __s, ios_base::openmode __mode)
     : basic_ostream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode | ios_base::out) == 0)
+    if (__sb_.open(__s, __mode | ios_base::out) == nullptr)
         this->setstate(ios_base::failbit);
 }
 #endif
@@ -1440,7 +1440,7 @@
 basic_ofstream<_CharT, _Traits>::basic_ofstream(const string& __s, ios_base::openmode __mode)
     : basic_ostream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode | ios_base::out) == 0)
+    if (__sb_.open(__s, __mode | ios_base::out) == nullptr)
         this->setstate(ios_base::failbit);
 }
 #endif
@@ -1549,7 +1549,7 @@
 void
 basic_ofstream<_CharT, _Traits>::close()
 {
-    if (__sb_.close() == 0)
+    if (__sb_.close() == nullptr)
         this->setstate(ios_base::failbit);
 }
 
@@ -1633,7 +1633,7 @@
 basic_fstream<_CharT, _Traits>::basic_fstream(const char* __s, ios_base::openmode __mode)
     : basic_iostream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode) == 0)
+    if (__sb_.open(__s, __mode) == nullptr)
         this->setstate(ios_base::failbit);
 }
 
@@ -1643,7 +1643,7 @@
 basic_fstream<_CharT, _Traits>::basic_fstream(const wchar_t* __s, ios_base::openmode __mode)
     : basic_iostream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode) == 0)
+    if (__sb_.open(__s, __mode) == nullptr)
         this->setstate(ios_base::failbit);
 }
 #endif
@@ -1653,7 +1653,7 @@
 basic_fstream<_CharT, _Traits>::basic_fstream(const string& __s, ios_base::openmode __mode)
     : basic_iostream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode) == 0)
+    if (__sb_.open(__s, __mode) == nullptr)
         this->setstate(ios_base::failbit);
 }
 #endif
@@ -1753,7 +1753,7 @@
 void
 basic_fstream<_CharT, _Traits>::close()
 {
-    if (__sb_.close() == 0)
+    if (__sb_.close() == nullptr)
         this->setstate(ios_base::failbit);
 }
 
Index: include/functional
===================================================================
--- include/functional
+++ include/functional
@@ -1663,7 +1663,7 @@
 {
     if (__ti == typeid(_Fp))
         return &__f_.__target();
-    return (const void*)0;
+    return nullptr;
 }
 
 template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
Index: include/ios
===================================================================
--- include/ios
+++ include/ios
@@ -709,7 +709,7 @@
 basic_ios<_CharT, _Traits>::init(basic_streambuf<char_type, traits_type>* __sb)
 {
     ios_base::init(__sb);
-    __tie_ = 0;
+    __tie_ = nullptr;
     __fill_ = traits_type::eof();
 }
 
@@ -820,7 +820,7 @@
 {
     ios_base::move(__rhs);
     __tie_ = __rhs.__tie_;
-    __rhs.__tie_ = 0;
+    __rhs.__tie_ = nullptr;
     __fill_ = __rhs.__fill_;
 }
 
Index: include/istream
===================================================================
--- include/istream
+++ include/istream
@@ -1142,7 +1142,7 @@
         try
         {
 #endif  // _LIBCPP_NO_EXCEPTIONS
-            if (this->rdbuf() == 0 || this->rdbuf()->sputbackc(__c) == traits_type::eof())
+            if (this->rdbuf() == nullptr || this->rdbuf()->sputbackc(__c) == traits_type::eof())
                 __state |= ios_base::badbit;
 #ifndef _LIBCPP_NO_EXCEPTIONS
         }
@@ -1179,7 +1179,7 @@
         try
         {
 #endif  // _LIBCPP_NO_EXCEPTIONS
-            if (this->rdbuf() == 0 || this->rdbuf()->sungetc() == traits_type::eof())
+            if (this->rdbuf() == nullptr || this->rdbuf()->sungetc() == traits_type::eof())
                 __state |= ios_base::badbit;
 #ifndef _LIBCPP_NO_EXCEPTIONS
         }
@@ -1215,7 +1215,7 @@
         try
         {
 #endif  // _LIBCPP_NO_EXCEPTIONS
-            if (this->rdbuf() == 0)
+            if (this->rdbuf() == nullptr)
                 return -1;
             if (this->rdbuf()->pubsync() == -1)
             {
Index: include/iterator
===================================================================
--- include/iterator
+++ include/iterator
@@ -447,14 +447,14 @@
 private:
     struct __two {char __lx; char __lxx;};
     template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename std::__void_t<typename _Up::iterator_category>::type* = 0,
-    										typename std::__void_t<typename _Up::difference_type>::type* = 0,
-    										typename std::__void_t<typename _Up::value_type>::type* = 0,
-    										typename std::__void_t<typename _Up::reference>::type* = 0,
-    										typename std::__void_t<typename _Up::pointer>::type* = 0
+    template <class _Up> static char __test(typename std::__void_t<typename _Up::iterator_category>::type* = nullptr,
+    										typename std::__void_t<typename _Up::difference_type>::type* = nullptr,
+    										typename std::__void_t<typename _Up::value_type>::type* = nullptr,
+    										typename std::__void_t<typename _Up::reference>::type* = nullptr,
+    										typename std::__void_t<typename _Up::pointer>::type* = nullptr
     										);
 public:
-    static const bool value = sizeof(__test<_Tp>(0,0,0,0,0)) == 1;
+    static const bool value = sizeof(__test<_Tp>(nullptr,nullptr,nullptr,nullptr,nullptr)) == 1;
 };
 
 
@@ -464,9 +464,9 @@
 private:
     struct __two {char __lx; char __lxx;};
     template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename _Up::iterator_category* = 0);
+    template <class _Up> static char __test(typename _Up::iterator_category* = nullptr);
 public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+    static const bool value = sizeof(__test<_Tp>(nullptr)) == 1;
 };
 
 template <class _Iter, bool> struct __iterator_traits_impl {};
@@ -915,11 +915,11 @@
     istream_type* __in_stream_;
     _Tp __value_;
 public:
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR istream_iterator() : __in_stream_(0), __value_() {}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR istream_iterator() : __in_stream_(nullptr), __value_() {}
     _LIBCPP_INLINE_VISIBILITY istream_iterator(istream_type& __s) : __in_stream_(_VSTD::addressof(__s))
         {
             if (!(*__in_stream_ >> __value_))
-                __in_stream_ = 0;
+                __in_stream_ = nullptr;
         }
 
     _LIBCPP_INLINE_VISIBILITY const _Tp& operator*() const {return __value_;}
@@ -927,7 +927,7 @@
     _LIBCPP_INLINE_VISIBILITY istream_iterator& operator++()
         {
             if (!(*__in_stream_ >> __value_))
-                __in_stream_ = 0;
+                __in_stream_ = nullptr;
             return *this;
         }
     _LIBCPP_INLINE_VISIBILITY istream_iterator  operator++(int)
@@ -977,7 +977,7 @@
     const char_type* __delim_;
 public:
     _LIBCPP_INLINE_VISIBILITY ostream_iterator(ostream_type& __s) _NOEXCEPT
-        : __out_stream_(_VSTD::addressof(__s)), __delim_(0) {}
+        : __out_stream_(_VSTD::addressof(__s)), __delim_(nullptr) {}
     _LIBCPP_INLINE_VISIBILITY ostream_iterator(ostream_type& __s, const _CharT* __delimiter) _NOEXCEPT
         : __out_stream_(_VSTD::addressof(__s)), __delim_(__delimiter) {}
     _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator=(const _Tp& __value_)
@@ -1023,11 +1023,11 @@
     bool __test_for_eof() const
     {
         if (__sbuf_ && traits_type::eq_int_type(__sbuf_->sgetc(), traits_type::eof()))
-            __sbuf_ = 0;
-        return __sbuf_ == 0;
+            __sbuf_ = nullptr;
+        return __sbuf_ == nullptr;
     }
 public:
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR istreambuf_iterator() _NOEXCEPT : __sbuf_(0) {}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR istreambuf_iterator() _NOEXCEPT : __sbuf_(nullptr) {}
     _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(istream_type& __s) _NOEXCEPT
         : __sbuf_(__s.rdbuf()) {}
     _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(streambuf_type* __s) _NOEXCEPT
@@ -1082,13 +1082,13 @@
     _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator=(_CharT __c)
         {
             if (__sbuf_ && traits_type::eq_int_type(__sbuf_->sputc(__c), traits_type::eof()))
-                __sbuf_ = 0;
+                __sbuf_ = nullptr;
             return *this;
         }
     _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator*()     {return *this;}
     _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++()    {return *this;}
     _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++(int) {return *this;}
-    _LIBCPP_INLINE_VISIBILITY bool failed() const _NOEXCEPT {return __sbuf_ == 0;}
+    _LIBCPP_INLINE_VISIBILITY bool failed() const _NOEXCEPT {return __sbuf_ == nullptr;}
 
     template <class _Ch, class _Tr>
     friend
@@ -1341,7 +1341,7 @@
     }
     template <class _Up> _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
         __wrap_iter(const __wrap_iter<_Up>& __u,
-            typename enable_if<is_convertible<_Up, iterator_type>::value>::type* = 0) _NOEXCEPT
+            typename enable_if<is_convertible<_Up, iterator_type>::value>::type* = nullptr) _NOEXCEPT
             : __i(__u.base())
     {
 #if _LIBCPP_DEBUG_LEVEL >= 2
Index: include/locale
===================================================================
--- include/locale
+++ include/locale
@@ -218,7 +218,7 @@
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 #if defined(__APPLE__) || defined(__FreeBSD__)
-#  define _LIBCPP_GET_C_LOCALE 0
+#  define _LIBCPP_GET_C_LOCALE nullptr
 #elif defined(__CloudABI__) || defined(__NetBSD__)
 #  define _LIBCPP_GET_C_LOCALE LC_C_LOCALE
 #else
@@ -261,11 +261,11 @@
     const unsigned char __does_match = '\2';
     unsigned char __statbuf[100];
     unsigned char* __status = __statbuf;
-    unique_ptr<unsigned char, void(*)(void*)> __stat_hold(0, free);
+    unique_ptr<unsigned char, void(*)(void*)> __stat_hold(nullptr, free);
     if (__nkw > sizeof(__statbuf))
     {
         __status = (unsigned char*)malloc(__nkw);
-        if (__status == 0)
+        if (__status == nullptr)
             __throw_bad_alloc();
         __stat_hold.reset(__status);
     }
@@ -1564,14 +1564,14 @@
                                    (int)__iob.precision(), __v);
     else
         __nc = __libcpp_snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-    unique_ptr<char, void(*)(void*)> __nbh(0, free);
+    unique_ptr<char, void(*)(void*)> __nbh(nullptr, free);
     if (__nc > static_cast<int>(__nbuf-1))
     {
         if (__specify_precision)
             __nc = __libcpp_asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, (int)__iob.precision(), __v);
         else
             __nc = __libcpp_asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-        if (__nb == 0)
+        if (__nb == nullptr)
             __throw_bad_alloc();
         __nbh.reset(__nb);
     }
@@ -1580,11 +1580,11 @@
     // Stage 2 - Widen __nar while adding thousands separators
     char_type __o[2*(__nbuf-1) - 1];
     char_type* __ob = __o;
-    unique_ptr<char_type, void(*)(void*)> __obh(0, free);
+    unique_ptr<char_type, void(*)(void*)> __obh(nullptr, free);
     if (__nb != __nar)
     {
         __ob = (char_type*)malloc(2*static_cast<size_t>(__nc)*sizeof(char_type));
-        if (__ob == 0)
+        if (__ob == nullptr)
             __throw_bad_alloc();
         __obh.reset(__ob);
     }
@@ -1615,14 +1615,14 @@
                                    (int)__iob.precision(), __v);
     else
         __nc = __libcpp_snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-    unique_ptr<char, void(*)(void*)> __nbh(0, free);
+    unique_ptr<char, void(*)(void*)> __nbh(nullptr, free);
     if (__nc > static_cast<int>(__nbuf-1))
     {
         if (__specify_precision)
             __nc = __libcpp_asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, (int)__iob.precision(), __v);
         else
             __nc = __libcpp_asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-        if (__nb == 0)
+        if (__nb == nullptr)
             __throw_bad_alloc();
         __nbh.reset(__nb);
     }
@@ -1631,11 +1631,11 @@
     // Stage 2 - Widen __nar while adding thousands separators
     char_type __o[2*(__nbuf-1) - 1];
     char_type* __ob = __o;
-    unique_ptr<char_type, void(*)(void*)> __obh(0, free);
+    unique_ptr<char_type, void(*)(void*)> __obh(nullptr, free);
     if (__nb != __nar)
     {
         __ob = (char_type*)malloc(2*static_cast<size_t>(__nc)*sizeof(char_type));
-        if (__ob == 0)
+        if (__ob == nullptr)
             __throw_bad_alloc();
         __obh.reset(__ob);
     }
@@ -2851,8 +2851,8 @@
     if (__new_cap == 0)
         __new_cap = sizeof(_Tp);
     size_t __n_off = static_cast<size_t>(__n - __b.get());
-    _Tp* __t = (_Tp*)realloc(__owns ? __b.get() : 0, __new_cap);
-    if (__t == 0)
+    _Tp* __t = (_Tp*)realloc(__owns ? __b.get() : nullptr, __new_cap);
+    if (__t == nullptr)
         __throw_bad_alloc();
     if (__owns)
         __b.release();
@@ -2892,7 +2892,7 @@
     int __fd;
     __money_get<_CharT>::__gather_info(__intl, __loc, __pat, __dp, __ts, __grp,
                                        __sym, __psn, __nsn, __fd);
-    const string_type* __trailing_sign = 0;
+    const string_type* __trailing_sign = nullptr;
     __wn = __wb.get();
     for (unsigned __p = 0; __p < 4 && __b != __e; ++__p)
     {
@@ -3108,11 +3108,11 @@
         __ct.widen(__src, __src + (sizeof(__src)-1), __atoms);
         char __nbuf[__bz];
         char* __nc = __nbuf;
-        unique_ptr<char, void(*)(void*)> __h(0, free);
+        unique_ptr<char, void(*)(void*)> __h(nullptr, free);
         if (__wn - __wb.get() > __bz-2)
         {
             __h.reset((char*)malloc(static_cast<size_t>(__wn - __wb.get() + 2)));
-            if (__h.get() == 0)
+            if (__h.get() == nullptr)
                 __throw_bad_alloc();
             __nc = __h.get();
         }
@@ -3397,13 +3397,13 @@
     char_type __digits[__bs];
     char_type* __db = __digits;
     size_t __n = static_cast<size_t>(snprintf(__bb, __bs, "%.0Lf", __units));
-    unique_ptr<char, void(*)(void*)> __hn(0, free);
-    unique_ptr<char_type, void(*)(void*)> __hd(0, free);
+    unique_ptr<char, void(*)(void*)> __hn(nullptr, free);
+    unique_ptr<char_type, void(*)(void*)> __hd(nullptr, free);
     // secure memory for digit storage
     if (__n > __bs-1)
     {
         __n = static_cast<size_t>(__libcpp_asprintf_l(&__bb, _LIBCPP_GET_C_LOCALE, "%.0Lf", __units));
-        if (__bb == 0)
+        if (__bb == nullptr)
             __throw_bad_alloc();
         __hn.reset(__bb);
         __hd.reset((char_type*)malloc(__n * sizeof(char_type)));
@@ -3427,7 +3427,7 @@
     // secure memory for formatting
     char_type __mbuf[__bs];
     char_type* __mb = __mbuf;
-    unique_ptr<char_type, void(*)(void*)> __hw(0, free);
+    unique_ptr<char_type, void(*)(void*)> __hw(nullptr, free);
     size_t __exn = static_cast<int>(__n) > __fd ?
                    (__n - static_cast<size_t>(__fd)) * 2 + __sn.size() +
                     __sym.size() + static_cast<size_t>(__fd) + 1
@@ -3436,7 +3436,7 @@
     {
         __hw.reset((char_type*)malloc(__exn * sizeof(char_type)));
         __mb = __hw.get();
-        if (__mb == 0)
+        if (__mb == nullptr)
             __throw_bad_alloc();
     }
     // format
@@ -3469,7 +3469,7 @@
     // secure memory for formatting
     char_type __mbuf[100];
     char_type* __mb = __mbuf;
-    unique_ptr<char_type, void(*)(void*)> __h(0, free);
+    unique_ptr<char_type, void(*)(void*)> __h(nullptr, free);
     size_t __exn = static_cast<int>(__digits.size()) > __fd ?
                    (__digits.size() - static_cast<size_t>(__fd)) * 2 +
                     __sn.size() + __sym.size() + static_cast<size_t>(__fd) + 1
@@ -3478,7 +3478,7 @@
     {
         __h.reset((char_type*)malloc(__exn * sizeof(char_type)));
         __mb = __h.get();
-        if (__mb == 0)
+        if (__mb == nullptr)
             __throw_bad_alloc();
     }
     // format
@@ -3923,7 +3923,7 @@
     wbuffer_convert(const wbuffer_convert&);
     wbuffer_convert& operator=(const wbuffer_convert&);
 public:
-    _LIBCPP_EXPLICIT_AFTER_CXX11 wbuffer_convert(streambuf* __bytebuf = 0,
+    _LIBCPP_EXPLICIT_AFTER_CXX11 wbuffer_convert(streambuf* __bytebuf = nullptr,
             _Codecvt* __pcvt = new _Codecvt, state_type __state = state_type());
     ~wbuffer_convert();
 
@@ -3961,9 +3961,9 @@
 template <class _Codecvt, class _Elem, class _Tr>
 wbuffer_convert<_Codecvt, _Elem, _Tr>::
     wbuffer_convert(streambuf* __bytebuf, _Codecvt* __pcvt, state_type __state)
-    : __extbuf_(0),
-      __extbufnext_(0),
-      __extbufend_(0),
+    : __extbuf_(nullptr),
+      __extbufnext_(nullptr),
+      __extbufend_(nullptr),
       __ebs_(0),
       __intbuf_(0),
       __ibs_(0),
Index: include/memory
===================================================================
--- include/memory
+++ include/memory
@@ -841,7 +841,7 @@
     template <class _Xp> static __two __test(...);
     template <class _Xp> static char __test(typename _Xp::template rebind<_Up>* = 0);
 public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+    static const bool value = sizeof(__test<_Tp>(nullptr)) == 1;
 };
 
 template <class _Tp, class _Up, bool = __has_rebind<_Tp, _Up>::value>
@@ -1258,7 +1258,7 @@
     template <class _Xp> static __two __test(...);
     template <class _Xp> static char __test(typename _Xp::template rebind<_Up>::other* = 0);
 public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+    static const bool value = sizeof(__test<_Tp>(nullptr)) == 1;
 };
 
 template <class _Tp, class _Up>
@@ -1805,7 +1805,7 @@
     _LIBCPP_INLINE_VISIBILITY const_pointer address(const_reference __x) const _NOEXCEPT
         {return _VSTD::addressof(__x);}
     _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
-    pointer allocate(size_type __n, allocator<void>::const_pointer = 0)
+    pointer allocate(size_type __n, allocator<void>::const_pointer = nullptr)
         {
         if (__n > max_size())
             __throw_length_error("allocator<T>::allocate(size_t n)"
@@ -1906,7 +1906,7 @@
 
     _LIBCPP_INLINE_VISIBILITY const_pointer address(const_reference __x) const _NOEXCEPT
         {return _VSTD::addressof(__x);}
-    _LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, allocator<void>::const_pointer = 0)
+    _LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, allocator<void>::const_pointer = nullptr)
     {
         if (__n > max_size())
             __throw_length_error("allocator<const T>::allocate(size_t n)"
@@ -2102,7 +2102,7 @@
     _LIBCPP_INLINE_VISIBILITY _Tp* release() throw()
     {
         _Tp* __t = __ptr_;
-        __ptr_ = 0;
+        __ptr_ = nullptr;
         return __t;
     }
     _LIBCPP_INLINE_VISIBILITY void reset(_Tp* __p = 0) throw()
@@ -4043,8 +4043,8 @@
 inline
 _LIBCPP_CONSTEXPR
 shared_ptr<_Tp>::shared_ptr() _NOEXCEPT
-    : __ptr_(0),
-      __cntrl_(0)
+    : __ptr_(nullptr),
+      __cntrl_(nullptr)
 {
 }
 
@@ -4052,8 +4052,8 @@
 inline
 _LIBCPP_CONSTEXPR
 shared_ptr<_Tp>::shared_ptr(nullptr_t) _NOEXCEPT
-    : __ptr_(0),
-      __cntrl_(0)
+    : __ptr_(nullptr),
+      __cntrl_(nullptr)
 {
 }
 
@@ -4098,7 +4098,7 @@
 template<class _Tp>
 template<class _Dp>
 shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d)
-    : __ptr_(0)
+    : __ptr_(nullptr)
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS
     try
@@ -4149,7 +4149,7 @@
 template<class _Tp>
 template<class _Dp, class _Alloc>
 shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a)
-    : __ptr_(0)
+    : __ptr_(nullptr)
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS
     try
@@ -4215,8 +4215,8 @@
     : __ptr_(__r.__ptr_),
       __cntrl_(__r.__cntrl_)
 {
-    __r.__ptr_ = 0;
-    __r.__cntrl_ = 0;
+    __r.__ptr_ = nullptr;
+    __r.__cntrl_ = nullptr;
 }
 
 template<class _Tp>
@@ -4228,8 +4228,8 @@
     : __ptr_(__r.__ptr_),
       __cntrl_(__r.__cntrl_)
 {
-    __r.__ptr_ = 0;
-    __r.__cntrl_ = 0;
+    __r.__ptr_ = nullptr;
+    __r.__cntrl_ = nullptr;
 }
 
 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
@@ -5090,8 +5090,8 @@
 inline
 _LIBCPP_CONSTEXPR
 weak_ptr<_Tp>::weak_ptr() _NOEXCEPT
-    : __ptr_(0),
-      __cntrl_(0)
+    : __ptr_(nullptr),
+      __cntrl_(nullptr)
 {
 }
 
@@ -5139,8 +5139,8 @@
     : __ptr_(__r.__ptr_),
       __cntrl_(__r.__cntrl_)
 {
-    __r.__ptr_ = 0;
-    __r.__cntrl_ = 0;
+    __r.__ptr_ = nullptr;
+    __r.__cntrl_ = nullptr;
 }
 
 template<class _Tp>
@@ -5152,8 +5152,8 @@
     : __ptr_(__r.__ptr_),
       __cntrl_(__r.__cntrl_)
 {
-    __r.__ptr_ = 0;
-    __r.__cntrl_ = 0;
+    __r.__ptr_ = nullptr;
+    __r.__cntrl_ = nullptr;
 }
 
 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
Index: include/regex
===================================================================
--- include/regex
+++ include/regex
@@ -2541,12 +2541,12 @@
     _LIBCPP_INLINE_VISIBILITY
     basic_regex()
         : __flags_(regex_constants::ECMAScript), __marked_count_(0), __loop_count_(0), __open_count_(0),
-          __end_(0)
+          __end_(nullptr)
         {}
     _LIBCPP_INLINE_VISIBILITY
     explicit basic_regex(const value_type* __p, flag_type __f = regex_constants::ECMAScript)
         : __flags_(__f), __marked_count_(0), __loop_count_(0), __open_count_(0),
-          __end_(0)
+          __end_(nullptr)
         {
         if (__get_grammar(__flags_) == 0) __flags_ |= regex_constants::ECMAScript;
         __parse(__p, __p + __traits_.length(__p));
@@ -2555,7 +2555,7 @@
     _LIBCPP_INLINE_VISIBILITY
     basic_regex(const value_type* __p, size_t __len, flag_type __f = regex_constants::ECMAScript)
         : __flags_(__f), __marked_count_(0), __loop_count_(0), __open_count_(0),
-          __end_(0)
+          __end_(nullptr)
         {
         if (__get_grammar(__flags_) == 0) __flags_ |= regex_constants::ECMAScript;
         __parse(__p, __p + __len);
@@ -2568,7 +2568,7 @@
         explicit basic_regex(const basic_string<value_type, _ST, _SA>& __p,
                              flag_type __f = regex_constants::ECMAScript)
         : __flags_(__f), __marked_count_(0), __loop_count_(0), __open_count_(0),
-          __end_(0)
+          __end_(nullptr)
         {
         if (__get_grammar(__flags_) == 0) __flags_ |= regex_constants::ECMAScript;
         __parse(__p.begin(), __p.end());
@@ -2579,7 +2579,7 @@
         basic_regex(_ForwardIterator __first, _ForwardIterator __last,
                     flag_type __f = regex_constants::ECMAScript)
         : __flags_(__f), __marked_count_(0), __loop_count_(0), __open_count_(0),
-          __end_(0)
+          __end_(nullptr)
         {
         if (__get_grammar(__flags_) == 0) __flags_ |= regex_constants::ECMAScript;
         __parse(__first, __last);
@@ -2589,7 +2589,7 @@
     basic_regex(initializer_list<value_type> __il,
                 flag_type __f = regex_constants::ECMAScript)
         : __flags_(__f), __marked_count_(0), __loop_count_(0), __open_count_(0),
-          __end_(0)
+          __end_(nullptr)
         {
         if (__get_grammar(__flags_) == 0) __flags_ |= regex_constants::ECMAScript;
         __parse(__il.begin(), __il.end());
Index: include/sstream
===================================================================
--- include/sstream
+++ include/sstream
@@ -239,7 +239,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 basic_stringbuf<_CharT, _Traits, _Allocator>::basic_stringbuf(ios_base::openmode __wch)
-    : __hm_(0),
+    : __hm_(nullptr),
       __mode_(__wch)
 {
 }
@@ -248,7 +248,7 @@
 basic_stringbuf<_CharT, _Traits, _Allocator>::basic_stringbuf(const string_type& __s,
                              ios_base::openmode __wch)
     : __str_(__s.get_allocator()),
-      __hm_(0),
+      __hm_(nullptr),
       __mode_(__wch)
 {
     str(__s);
@@ -453,7 +453,7 @@
 basic_stringbuf<_CharT, _Traits, _Allocator>::str(const string_type& __s)
 {
     __str_ = __s;
-    __hm_ = 0;
+    __hm_ = nullptr;
     if (__mode_ & ios_base::in)
     {
         __hm_ = const_cast<char_type*>(__str_.data()) + __str_.size();
@@ -600,9 +600,9 @@
         return pos_type(-1);
     if (__noff != 0)
     {
-        if ((__wch & ios_base::in) && this->gptr() == 0)
+        if ((__wch & ios_base::in) && this->gptr() == nullptr)
             return pos_type(-1);
-        if ((__wch & ios_base::out) && this->pptr() == 0)
+        if ((__wch & ios_base::out) && this->pptr() == nullptr)
             return pos_type(-1);
     }
     if (__wch & ios_base::in)
Index: include/streambuf
===================================================================
--- include/streambuf
+++ include/streambuf
@@ -308,12 +308,12 @@
 
 template <class _CharT, class _Traits>
 basic_streambuf<_CharT, _Traits>::basic_streambuf()
-    : __binp_(0),
-      __ninp_(0),
-      __einp_(0),
-      __bout_(0),
-      __nout_(0),
-      __eout_(0)
+    : __binp_(nullptr),
+      __ninp_(nullptr),
+      __einp_(nullptr),
+      __bout_(nullptr),
+      __nout_(nullptr),
+      __eout_(nullptr)
 {
 }
 
Index: include/string
===================================================================
--- include/string
+++ include/string
@@ -446,15 +446,15 @@
 typedef basic_string<char16_t> u16string;
 typedef basic_string<char32_t> u32string;
 
-int                stoi  (const string& str, size_t* idx = 0, int base = 10);
-long               stol  (const string& str, size_t* idx = 0, int base = 10);
-unsigned long      stoul (const string& str, size_t* idx = 0, int base = 10);
-long long          stoll (const string& str, size_t* idx = 0, int base = 10);
-unsigned long long stoull(const string& str, size_t* idx = 0, int base = 10);
+int                stoi  (const string& str, size_t* idx = nullptr, int base = 10);
+long               stol  (const string& str, size_t* idx = nullptr, int base = 10);
+unsigned long      stoul (const string& str, size_t* idx = nullptr, int base = 10);
+long long          stoll (const string& str, size_t* idx = nullptr, int base = 10);
+unsigned long long stoull(const string& str, size_t* idx = nullptr, int base = 10);
 
-float       stof (const string& str, size_t* idx = 0);
-double      stod (const string& str, size_t* idx = 0);
-long double stold(const string& str, size_t* idx = 0);
+float       stof (const string& str, size_t* idx = nullptr);
+double      stod (const string& str, size_t* idx = nullptr);
+long double stold(const string& str, size_t* idx = nullptr);
 
 string to_string(int val);
 string to_string(unsigned val);
@@ -466,15 +466,15 @@
 string to_string(double val);
 string to_string(long double val);
 
-int                stoi  (const wstring& str, size_t* idx = 0, int base = 10);
-long               stol  (const wstring& str, size_t* idx = 0, int base = 10);
-unsigned long      stoul (const wstring& str, size_t* idx = 0, int base = 10);
-long long          stoll (const wstring& str, size_t* idx = 0, int base = 10);
-unsigned long long stoull(const wstring& str, size_t* idx = 0, int base = 10);
+int                stoi  (const wstring& str, size_t* idx = nullptr, int base = 10);
+long               stol  (const wstring& str, size_t* idx = nullptr, int base = 10);
+unsigned long      stoul (const wstring& str, size_t* idx = nullptr, int base = 10);
+long long          stoll (const wstring& str, size_t* idx = nullptr, int base = 10);
+unsigned long long stoull(const wstring& str, size_t* idx = nullptr, int base = 10);
 
-float       stof (const wstring& str, size_t* idx = 0);
-double      stod (const wstring& str, size_t* idx = 0);
-long double stold(const wstring& str, size_t* idx = 0);
+float       stof (const wstring& str, size_t* idx = nullptr);
+double      stod (const wstring& str, size_t* idx = nullptr);
+long double stold(const wstring& str, size_t* idx = nullptr);
 
 wstring to_wstring(int val);
 wstring to_wstring(unsigned val);
@@ -3813,7 +3813,7 @@
         return false;
     if (capacity() < __min_cap - 1)
         return false;
-    if (data() == 0)
+    if (data() == nullptr)
         return false;
     if (data()[size()] != value_type(0))
         return false;
@@ -4183,15 +4183,15 @@
 typedef basic_string<char32_t> u32string;
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
 
-_LIBCPP_FUNC_VIS int                stoi  (const string& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS long               stol  (const string& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS unsigned long      stoul (const string& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS long long          stoll (const string& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS unsigned long long stoull(const string& __str, size_t* __idx = 0, int __base = 10);
+_LIBCPP_FUNC_VIS int                stoi  (const string& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS long               stol  (const string& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS unsigned long      stoul (const string& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS long long          stoll (const string& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS unsigned long long stoull(const string& __str, size_t* __idx = nullptr, int __base = 10);
 
-_LIBCPP_FUNC_VIS float       stof (const string& __str, size_t* __idx = 0);
-_LIBCPP_FUNC_VIS double      stod (const string& __str, size_t* __idx = 0);
-_LIBCPP_FUNC_VIS long double stold(const string& __str, size_t* __idx = 0);
+_LIBCPP_FUNC_VIS float       stof (const string& __str, size_t* __idx = nullptr);
+_LIBCPP_FUNC_VIS double      stod (const string& __str, size_t* __idx = nullptr);
+_LIBCPP_FUNC_VIS long double stold(const string& __str, size_t* __idx = nullptr);
 
 _LIBCPP_FUNC_VIS string to_string(int __val);
 _LIBCPP_FUNC_VIS string to_string(unsigned __val);
@@ -4203,15 +4203,15 @@
 _LIBCPP_FUNC_VIS string to_string(double __val);
 _LIBCPP_FUNC_VIS string to_string(long double __val);
 
-_LIBCPP_FUNC_VIS int                stoi  (const wstring& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS long               stol  (const wstring& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS unsigned long      stoul (const wstring& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS long long          stoll (const wstring& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS unsigned long long stoull(const wstring& __str, size_t* __idx = 0, int __base = 10);
+_LIBCPP_FUNC_VIS int                stoi  (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS long               stol  (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS unsigned long      stoul (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS long long          stoll (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS unsigned long long stoull(const wstring& __str, size_t* __idx = nullptr, int __base = 10);
 
-_LIBCPP_FUNC_VIS float       stof (const wstring& __str, size_t* __idx = 0);
-_LIBCPP_FUNC_VIS double      stod (const wstring& __str, size_t* __idx = 0);
-_LIBCPP_FUNC_VIS long double stold(const wstring& __str, size_t* __idx = 0);
+_LIBCPP_FUNC_VIS float       stof (const wstring& __str, size_t* __idx = nullptr);
+_LIBCPP_FUNC_VIS double      stod (const wstring& __str, size_t* __idx = nullptr);
+_LIBCPP_FUNC_VIS long double stold(const wstring& __str, size_t* __idx = nullptr);
 
 _LIBCPP_FUNC_VIS wstring to_wstring(int __val);
 _LIBCPP_FUNC_VIS wstring to_wstring(unsigned __val);
Index: include/strstream
===================================================================
--- include/strstream
+++ include/strstream
@@ -19,12 +19,12 @@
 public:
     explicit strstreambuf(streamsize alsize_arg = 0);
     strstreambuf(void* (*palloc_arg)(size_t), void (*pfree_arg)(void*));
-    strstreambuf(char* gnext_arg, streamsize n, char* pbeg_arg = 0);
+    strstreambuf(char* gnext_arg, streamsize n, char* pbeg_arg = nullptr);
     strstreambuf(const char* gnext_arg, streamsize n);
 
-    strstreambuf(signed char* gnext_arg, streamsize n, signed char* pbeg_arg = 0);
+    strstreambuf(signed char* gnext_arg, streamsize n, signed char* pbeg_arg = nullptr);
     strstreambuf(const signed char* gnext_arg, streamsize n);
-    strstreambuf(unsigned char* gnext_arg, streamsize n, unsigned char* pbeg_arg = 0);
+    strstreambuf(unsigned char* gnext_arg, streamsize n, unsigned char* pbeg_arg = nullptr);
     strstreambuf(const unsigned char* gnext_arg, streamsize n);
 
     strstreambuf(strstreambuf&& rhs);
@@ -142,12 +142,12 @@
 public:
     explicit strstreambuf(streamsize __alsize = 0);
     strstreambuf(void* (*__palloc)(size_t), void (*__pfree)(void*));
-    strstreambuf(char* __gnext, streamsize __n, char* __pbeg = 0);
+    strstreambuf(char* __gnext, streamsize __n, char* __pbeg = nullptr);
     strstreambuf(const char* __gnext, streamsize __n);
 
-    strstreambuf(signed char* __gnext, streamsize __n, signed char* __pbeg = 0);
+    strstreambuf(signed char* __gnext, streamsize __n, signed char* __pbeg = nullptr);
     strstreambuf(const signed char* __gnext, streamsize __n);
-    strstreambuf(unsigned char* __gnext, streamsize __n, unsigned char* __pbeg = 0);
+    strstreambuf(unsigned char* __gnext, streamsize __n, unsigned char* __pbeg = nullptr);
     strstreambuf(const unsigned char* __gnext, streamsize __n);
 
 #ifndef _LIBCPP_CXX03_LANG
Index: include/system_error
===================================================================
--- include/system_error
+++ include/system_error
@@ -253,7 +253,7 @@
     template <class _Ep>
         _LIBCPP_INLINE_VISIBILITY
         error_condition(_Ep __e,
-              typename enable_if<is_error_condition_enum<_Ep>::value>::type* = 0
+              typename enable_if<is_error_condition_enum<_Ep>::value>::type* = nullptr
                                                                      ) _NOEXCEPT
             {*this = make_error_condition(__e);}
 
@@ -325,7 +325,7 @@
     template <class _Ep>
         _LIBCPP_INLINE_VISIBILITY
         error_code(_Ep __e,
-                   typename enable_if<is_error_code_enum<_Ep>::value>::type* = 0
+                   typename enable_if<is_error_code_enum<_Ep>::value>::type* = nullptr
                                                                      ) _NOEXCEPT
             {*this = make_error_code(__e);}
 
Index: include/type_traits
===================================================================
--- include/type_traits
+++ include/type_traits
@@ -868,7 +868,7 @@
 }
 
 template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_class
-    : public integral_constant<bool, sizeof(__is_class_imp::__test<_Tp>(0)) == 1 && !is_union<_Tp>::value> {};
+    : public integral_constant<bool, sizeof(__is_class_imp::__test<_Tp>(nullptr)) == 1 && !is_union<_Tp>::value> {};
 
 #endif
 
@@ -1668,7 +1668,7 @@
 template<typename _Tp> __two &__is_polymorphic_impl(...);
 
 template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_polymorphic
-    : public integral_constant<bool, sizeof(__is_polymorphic_impl<_Tp>(0)) == 1> {};
+    : public integral_constant<bool, sizeof(__is_polymorphic_impl<_Tp>(nullptr)) == 1> {};
 
 #endif // __has_feature(is_polymorphic)
 
Index: include/valarray
===================================================================
--- include/valarray
+++ include/valarray
@@ -802,7 +802,7 @@
 public:
     // construct/destroy:
     _LIBCPP_INLINE_VISIBILITY
-    valarray() : __begin_(0), __end_(0) {}
+    valarray() : __begin_(nullptr), __end_(nullptr) {}
     inline _LIBCPP_HIDE_FROM_ABI_AFTER_V1
     explicit valarray(size_t __n);
     _LIBCPP_INLINE_VISIBILITY
@@ -2764,8 +2764,8 @@
 template <class _Tp>
 inline
 valarray<_Tp>::valarray(size_t __n)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     if (__n)
     {
@@ -2791,16 +2791,16 @@
 template <class _Tp>
 inline
 valarray<_Tp>::valarray(const value_type& __x, size_t __n)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     resize(__n, __x);
 }
 
 template <class _Tp>
 valarray<_Tp>::valarray(const value_type* __p, size_t __n)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     if (__n)
     {
@@ -2825,8 +2825,8 @@
 
 template <class _Tp>
 valarray<_Tp>::valarray(const valarray& __v)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     if (__v.size())
     {
@@ -2862,8 +2862,8 @@
 
 template <class _Tp>
 valarray<_Tp>::valarray(initializer_list<value_type> __il)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     const size_t __n = __il.size();
     if (__n)
@@ -2892,8 +2892,8 @@
 
 template <class _Tp>
 valarray<_Tp>::valarray(const slice_array<value_type>& __sa)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     const size_t __n = __sa.__size_;
     if (__n)
@@ -2920,8 +2920,8 @@
 
 template <class _Tp>
 valarray<_Tp>::valarray(const gslice_array<value_type>& __ga)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     const size_t __n = __ga.__1d_.size();
     if (__n)
@@ -2950,8 +2950,8 @@
 
 template <class _Tp>
 valarray<_Tp>::valarray(const mask_array<value_type>& __ma)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     const size_t __n = __ma.__1d_.size();
     if (__n)
@@ -2980,8 +2980,8 @@
 
 template <class _Tp>
 valarray<_Tp>::valarray(const indirect_array<value_type>& __ia)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     const size_t __n = __ia.__1d_.size();
     if (__n)
Index: src/ios.cpp
===================================================================
--- src/ios.cpp
+++ src/ios.cpp
@@ -182,7 +182,7 @@
     {
         size_t newcap = __ios_new_cap<long>(req_size, __iarray_cap_);
         long* iarray = static_cast<long*>(realloc(__iarray_, newcap * sizeof(long)));
-        if (iarray == 0)
+        if (iarray == nullptr)
         {
             setstate(badbit);
             static long error;
@@ -206,16 +206,16 @@
     {
         size_t newcap = __ios_new_cap<void *>(req_size, __iarray_cap_);
         void** parray = static_cast<void**>(realloc(__parray_, newcap * sizeof(void *)));
-        if (parray == 0)
+        if (parray == nullptr)
         {
             setstate(badbit);
             static void* error;
-            error = 0;
+            error = nullptr;
             return error;
         }
         __parray_ = parray;
         for (void** p = __parray_ + __parray_size_; p < __parray_ + newcap; ++p)
-            *p = 0;
+            *p = nullptr;
         __parray_cap_ = newcap;
     }
     __parray_size_ = max<size_t>(__parray_size_, req_size);
@@ -232,11 +232,11 @@
     {
         size_t newcap = __ios_new_cap<event_callback>(req_size, __event_cap_);
         event_callback* fns = static_cast<event_callback*>(realloc(__fn_, newcap * sizeof(event_callback)));
-        if (fns == 0)
+        if (fns == nullptr)
             setstate(badbit);
         __fn_ = fns;
         int* indxs = static_cast<int *>(realloc(__index_, newcap * sizeof(int)));
-        if (indxs == 0)
+        if (indxs == nullptr)
             setstate(badbit);
         __index_ = indxs;
         __event_cap_ = newcap;
@@ -282,14 +282,14 @@
     __fmtflags_ = skipws | dec;
     __width_ = 0;
     __precision_ = 6;
-    __fn_ = 0;
-    __index_ = 0;
+    __fn_ = nullptr;
+    __index_ = nullptr;
     __event_size_ = 0;
     __event_cap_ = 0;
-    __iarray_ = 0;
+    __iarray_ = nullptr;
     __iarray_size_ = 0;
     __iarray_cap_ = 0;
-    __parray_ = 0;
+    __parray_ = nullptr;
     __parray_size_ = 0;
     __parray_cap_ = 0;
     ::new(&__loc_) locale;
@@ -300,10 +300,10 @@
 {
     // If we can't acquire the needed resources, throw bad_alloc (can't set badbit)
     // Don't alter *this until all needed resources are acquired
-    unique_ptr<event_callback, void (*)(void*)> new_callbacks(0, free);
-    unique_ptr<int, void (*)(void*)> new_ints(0, free);
-    unique_ptr<long, void (*)(void*)> new_longs(0, free);
-    unique_ptr<void*, void (*)(void*)> new_pointers(0, free);
+    unique_ptr<event_callback, void (*)(void*)> new_callbacks(nullptr, free);
+    unique_ptr<int, void (*)(void*)> new_ints(nullptr, free);
+    unique_ptr<long, void (*)(void*)> new_longs(nullptr, free);
+    unique_ptr<void*, void (*)(void*)> new_pointers(nullptr, free);
     if (__event_cap_ < rhs.__event_size_)
     {
         size_t newesize = sizeof(event_callback) * rhs.__event_size_;
@@ -377,25 +377,25 @@
     __width_ = rhs.__width_;
     __rdstate_ = rhs.__rdstate_;
     __exceptions_ = rhs.__exceptions_;
-    __rdbuf_ = 0;
+    __rdbuf_ = nullptr;
     locale& rhs_loc = *reinterpret_cast<locale*>(&rhs.__loc_);
     ::new(&__loc_) locale(rhs_loc);
     __fn_ = rhs.__fn_;
-    rhs.__fn_ = 0;
+    rhs.__fn_ = nullptr;
     __index_ = rhs.__index_;
-    rhs.__index_ = 0;
+    rhs.__index_ = nullptr;
     __event_size_ = rhs.__event_size_;
     rhs.__event_size_ = 0;
     __event_cap_ = rhs.__event_cap_;
     rhs.__event_cap_ = 0;
     __iarray_ = rhs.__iarray_;
-    rhs.__iarray_ = 0;
+    rhs.__iarray_ = nullptr;
     __iarray_size_ = rhs.__iarray_size_;
     rhs.__iarray_size_ = 0;
     __iarray_cap_ = rhs.__iarray_cap_;
     rhs.__iarray_cap_ = 0;
     __parray_ = rhs.__parray_;
-    rhs.__parray_ = 0;
+    rhs.__parray_ = nullptr;
     __parray_size_ = rhs.__parray_size_;
     rhs.__parray_size_ = 0;
     __parray_cap_ = rhs.__parray_cap_;
Index: src/locale.cpp
===================================================================
--- src/locale.cpp
+++ src/locale.cpp
@@ -47,7 +47,7 @@
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 struct __libcpp_unique_locale {
-  __libcpp_unique_locale(const char* nm) : __loc_(newlocale(LC_ALL_MASK, nm, 0)) {}
+  __libcpp_unique_locale(const char* nm) : __loc_(newlocale(LC_ALL_MASK, nm, nullptr)) {}
 
   ~__libcpp_unique_locale() {
     if (__loc_)
@@ -536,7 +536,7 @@
 
 locale::locale(const char* name)
     : __locale_(name ? new __imp(name)
-                     : (__throw_runtime_error("locale constructed with null"), (__imp*)0))
+                     : (__throw_runtime_error("locale constructed with null"), nullptr))
 {
     __locale_->__add_shared();
 }
@@ -549,7 +549,7 @@
 
 locale::locale(const locale& other, const char* name, category c)
     : __locale_(name ? new __imp(*other.__locale_, name, c)
-                     : (__throw_runtime_error("locale constructed with null"), (__imp*)0))
+                     : (__throw_runtime_error("locale constructed with null"), nullptr))
 {
     __locale_->__add_shared();
 }
@@ -664,18 +664,18 @@
 
 collate_byname<char>::collate_byname(const char* n, size_t refs)
     : collate<char>(refs),
-      __l(newlocale(LC_ALL_MASK, n, 0))
+      __l(newlocale(LC_ALL_MASK, n, nullptr))
 {
-    if (__l == 0)
+    if (__l == nullptr)
         __throw_runtime_error("collate_byname<char>::collate_byname"
                             " failed to construct for " + string(n));
 }
 
 collate_byname<char>::collate_byname(const string& name, size_t refs)
     : collate<char>(refs),
-      __l(newlocale(LC_ALL_MASK, name.c_str(), 0))
+      __l(newlocale(LC_ALL_MASK, name.c_str(), nullptr))
 {
-    if (__l == 0)
+    if (__l == nullptr)
         __throw_runtime_error("collate_byname<char>::collate_byname"
                             " failed to construct for " + name);
 }
@@ -703,7 +703,7 @@
 collate_byname<char>::do_transform(const char_type* lo, const char_type* hi) const
 {
     const string_type in(lo, hi);
-    string_type out(strxfrm_l(0, in.c_str(), 0, __l), char());
+    string_type out(strxfrm_l(nullptr, in.c_str(), 0, __l), char());
     strxfrm_l(const_cast<char*>(out.c_str()), in.c_str(), out.size()+1, __l);
     return out;
 }
@@ -712,18 +712,18 @@
 
 collate_byname<wchar_t>::collate_byname(const char* n, size_t refs)
     : collate<wchar_t>(refs),
-      __l(newlocale(LC_ALL_MASK, n, 0))
+      __l(newlocale(LC_ALL_MASK, n, nullptr))
 {
-    if (__l == 0)
+    if (__l == nullptr)
         __throw_runtime_error("collate_byname<wchar_t>::collate_byname(size_t refs)"
                             " failed to construct for " + string(n));
 }
 
 collate_byname<wchar_t>::collate_byname(const string& name, size_t refs)
     : collate<wchar_t>(refs),
-      __l(newlocale(LC_ALL_MASK, name.c_str(), 0))
+      __l(newlocale(LC_ALL_MASK, name.c_str(), nullptr))
 {
-    if (__l == 0)
+    if (__l == nullptr)
         __throw_runtime_error("collate_byname<wchar_t>::collate_byname(size_t refs)"
                             " failed to construct for " + name);
 }
@@ -751,7 +751,7 @@
 collate_byname<wchar_t>::do_transform(const char_type* lo, const char_type* hi) const
 {
     const string_type in(lo, hi);
-    string_type out(wcsxfrm_l(0, in.c_str(), 0, __l), wchar_t());
+    string_type out(wcsxfrm_l(nullptr, in.c_str(), 0, __l), wchar_t());
     wcsxfrm_l(const_cast<wchar_t*>(out.c_str()), in.c_str(), out.size()+1, __l);
     return out;
 }
@@ -910,7 +910,7 @@
       __tab_(tab),
       __del_(del)
 {
-  if (__tab_ == 0)
+  if (__tab_ == nullptr)
       __tab_ = classic_table();
 }
 
@@ -1179,19 +1179,19 @@
 // template <> class ctype_byname<char>
 
 ctype_byname<char>::ctype_byname(const char* name, size_t refs)
-    : ctype<char>(0, false, refs),
-      __l(newlocale(LC_ALL_MASK, name, 0))
+    : ctype<char>(nullptr, false, refs),
+      __l(newlocale(LC_ALL_MASK, name, nullptr))
 {
-    if (__l == 0)
+    if (__l == nullptr)
         __throw_runtime_error("ctype_byname<char>::ctype_byname"
                             " failed to construct for " + string(name));
 }
 
 ctype_byname<char>::ctype_byname(const string& name, size_t refs)
-    : ctype<char>(0, false, refs),
-      __l(newlocale(LC_ALL_MASK, name.c_str(), 0))
+    : ctype<char>(nullptr, false, refs),
+      __l(newlocale(LC_ALL_MASK, name.c_str(), nullptr))
 {
-    if (__l == 0)
+    if (__l == nullptr)
         __throw_runtime_error("ctype_byname<char>::ctype_byname"
                             " failed to construct for " + name);
 }
@@ -1233,18 +1233,18 @@
 
 ctype_byname<wchar_t>::ctype_byname(const char* name, size_t refs)
     : ctype<wchar_t>(refs),
-      __l(newlocale(LC_ALL_MASK, name, 0))
+      __l(newlocale(LC_ALL_MASK, name, nullptr))
 {
-    if (__l == 0)
+    if (__l == nullptr)
         __throw_runtime_error("ctype_byname<wchar_t>::ctype_byname"
                             " failed to construct for " + string(name));
 }
 
 ctype_byname<wchar_t>::ctype_byname(const string& name, size_t refs)
     : ctype<wchar_t>(refs),
-      __l(newlocale(LC_ALL_MASK, name.c_str(), 0))
+      __l(newlocale(LC_ALL_MASK, name.c_str(), nullptr))
 {
-    if (__l == 0)
+    if (__l == nullptr)
         __throw_runtime_error("ctype_byname<wchar_t>::ctype_byname"
                             " failed to construct for " + name);
 }
@@ -1504,9 +1504,9 @@
 
 codecvt<wchar_t, char, mbstate_t>::codecvt(const char* nm, size_t refs)
     : locale::facet(refs),
-      __l(newlocale(LC_ALL_MASK, nm, 0))
+      __l(newlocale(LC_ALL_MASK, nm, nullptr))
 {
-    if (__l == 0)
+    if (__l == nullptr)
         __throw_runtime_error("codecvt_byname<wchar_t, char, mbstate_t>::codecvt_byname"
                             " failed to construct for " + string(nm));
 }
@@ -1664,7 +1664,7 @@
         return -1;
 
     // stateless encoding
-    if (__l == 0 || __libcpp_mb_cur_max_l(__l) == 1)  // there are no known constant length encodings
+    if (__l == nullptr || __libcpp_mb_cur_max_l(__l) == 1)  // there are no known constant length encodings
         return 1;                // which take more than 1 char to form a wchar_t
     return 0;
 }
@@ -1704,7 +1704,7 @@
 int
 codecvt<wchar_t, char, mbstate_t>::do_max_length() const  _NOEXCEPT
 {
-    return __l == 0 ? 1 : static_cast<int>(__libcpp_mb_cur_max_l(__l));
+    return __l == nullptr ? 1 : static_cast<int>(__libcpp_mb_cur_max_l(__l));
 }
 
 //                                     Valid UTF ranges
@@ -4748,17 +4748,17 @@
 // time_get_byname
 
 __time_get::__time_get(const char* nm)
-    : __loc_(newlocale(LC_ALL_MASK, nm, 0))
+    : __loc_(newlocale(LC_ALL_MASK, nm, nullptr))
 {
-    if (__loc_ == 0)
+    if (__loc_ == nullptr)
         __throw_runtime_error("time_get_byname"
                             " failed to construct for " + string(nm));
 }
 
 __time_get::__time_get(const string& nm)
-    : __loc_(newlocale(LC_ALL_MASK, nm.c_str(), 0))
+    : __loc_(newlocale(LC_ALL_MASK, nm.c_str(), nullptr))
 {
-    if (__loc_ == 0)
+    if (__loc_ == nullptr)
         __throw_runtime_error("time_get_byname"
                             " failed to construct for " + nm);
 }
@@ -5404,17 +5404,17 @@
 // time_put
 
 __time_put::__time_put(const char* nm)
-    : __loc_(newlocale(LC_ALL_MASK, nm, 0))
+    : __loc_(newlocale(LC_ALL_MASK, nm, nullptr))
 {
-    if (__loc_ == 0)
+    if (__loc_ == nullptr)
         __throw_runtime_error("time_put_byname"
                             " failed to construct for " + string(nm));
 }
 
 __time_put::__time_put(const string& nm)
-    : __loc_(newlocale(LC_ALL_MASK, nm.c_str(), 0))
+    : __loc_(newlocale(LC_ALL_MASK, nm.c_str(), nullptr))
 {
-    if (__loc_ == 0)
+    if (__loc_ == nullptr)
         __throw_runtime_error("time_put_byname"
                             " failed to construct for " + nm);
 }
Index: src/new.cpp
===================================================================
--- src/new.cpp
+++ src/new.cpp
@@ -64,7 +64,7 @@
     if (size == 0)
         size = 1;
     void* p;
-    while ((p = ::malloc(size)) == 0)
+    while ((p = ::malloc(size)) == nullptr)
     {
         // If malloc fails and there is a new_handler,
         // call it to try free up memory.
@@ -85,7 +85,7 @@
 void*
 operator new(size_t size, const std::nothrow_t&) _NOEXCEPT
 {
-    void* p = 0;
+    void* p = nullptr;
 #ifndef _LIBCPP_NO_EXCEPTIONS
     try
     {
@@ -111,7 +111,7 @@
 void*
 operator new[](size_t size, const std::nothrow_t&) _NOEXCEPT
 {
-    void* p = 0;
+    void* p = nullptr;
 #ifndef _LIBCPP_NO_EXCEPTIONS
     try
     {
@@ -206,7 +206,7 @@
 void*
 operator new(size_t size, std::align_val_t alignment, const std::nothrow_t&) _NOEXCEPT
 {
-    void* p = 0;
+    void* p = nullptr;
 #ifndef _LIBCPP_NO_EXCEPTIONS
     try
     {
@@ -232,7 +232,7 @@
 void*
 operator new[](size_t size, std::align_val_t alignment, const std::nothrow_t&) _NOEXCEPT
 {
-    void* p = 0;
+    void* p = nullptr;
 #ifndef _LIBCPP_NO_EXCEPTIONS
     try
     {
Index: src/thread.cpp
===================================================================
--- src/thread.cpp
+++ src/thread.cpp
@@ -84,7 +84,7 @@
     unsigned n;
     int mib[2] = {CTL_HW, HW_NCPU};
     std::size_t s = sizeof(n);
-    sysctl(mib, 2, &n, &s, 0, 0);
+    sysctl(mib, 2, &n, &s, nullptr, 0);
     return n;
 #elif defined(_SC_NPROCESSORS_ONLN)
     long result = sysconf(_SC_NPROCESSORS_ONLN);