libcxx: update to LLVM 18

release/18.x branch, commit 78b99c73ee4b96fe9ce0e294d4632326afb2db42

This adds the flag `-D_LIBCPP_HARDENING_MODE` which is determined based
on the Zig optimization mode.

This commit also fixes libunwind, libcxx, and libcxxabi to properly
report sub compilation errors.

1 files changed, 956 insertions, 1182 deletions

diff --git a/lib/libcxx/include/fstream b/lib/libcxx/include/fstream
index d30575e22a..203cc6dfb4 100644
--- a/lib/libcxx/include/fstream
+++ b/lib/libcxx/include/fstream
@@ -73,6 +73,7 @@ public:
     typedef typename traits_type::int_type int_type;
     typedef typename traits_type::pos_type pos_type;
     typedef typename traits_type::off_type off_type;
+    using native_handle_type = typename basic_filebuf<charT, traits>::native_handle_type; // Since C++26
 
     basic_ifstream();
     explicit basic_ifstream(const char* s, ios_base::openmode mode = ios_base::in);
@@ -85,6 +86,7 @@ public:
     void swap(basic_ifstream& rhs);
 
     basic_filebuf<char_type, traits_type>* rdbuf() const;
+    native_handle_type native_handle() const noexcept; // Since C++26
     bool is_open() const;
     void open(const char* s, ios_base::openmode mode = ios_base::in);
     void open(const string& s, ios_base::openmode mode = ios_base::in);
@@ -110,6 +112,7 @@ public:
     typedef typename traits_type::int_type int_type;
     typedef typename traits_type::pos_type pos_type;
     typedef typename traits_type::off_type off_type;
+    using native_handle_type = typename basic_filebuf<charT, traits>::native_handle_type; // Since C++26
 
     basic_ofstream();
     explicit basic_ofstream(const char* s, ios_base::openmode mode = ios_base::out);
@@ -122,6 +125,8 @@ public:
     void swap(basic_ofstream& rhs);
 
     basic_filebuf<char_type, traits_type>* rdbuf() const;
+    native_handle_type native_handle() const noexcept; // Since C++26
+
     bool is_open() const;
     void open(const char* s, ios_base::openmode mode = ios_base::out);
     void open(const string& s, ios_base::openmode mode = ios_base::out);
@@ -148,6 +153,7 @@ public:
     typedef typename traits_type::int_type int_type;
     typedef typename traits_type::pos_type pos_type;
     typedef typename traits_type::off_type off_type;
+    using native_handle_type = typename basic_filebuf<charT, traits>::native_handle_type; // Since C++26
 
     basic_fstream();
     explicit basic_fstream(const char* s, ios_base::openmode mode = ios_base::in|ios_base::out);
@@ -160,6 +166,7 @@ public:
     void swap(basic_fstream& rhs);
 
     basic_filebuf<char_type, traits_type>* rdbuf() const;
+    native_handle_type native_handle() const noexcept; // Since C++26
     bool is_open() const;
     void open(const char* s, ios_base::openmode mode = ios_base::in|ios_base::out);
     void open(const string& s, ios_base::openmode mode = ios_base::in|ios_base::out);
@@ -210,64 +217,80 @@ _LIBCPP_PUSH_MACROS
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+#  if _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_WIN32API)
+_LIBCPP_EXPORTED_FROM_ABI void* __filebuf_windows_native_handle(FILE* __file) noexcept;
+#  endif
+
 template <class _CharT, class _Traits>
-class _LIBCPP_TEMPLATE_VIS basic_filebuf
-    : public basic_streambuf<_CharT, _Traits>
-{
+class _LIBCPP_TEMPLATE_VIS basic_filebuf : public basic_streambuf<_CharT, _Traits> {
 public:
-    typedef _CharT                           char_type;
-    typedef _Traits                          traits_type;
-    typedef typename traits_type::int_type   int_type;
-    typedef typename traits_type::pos_type   pos_type;
-    typedef typename traits_type::off_type   off_type;
-    typedef typename traits_type::state_type state_type;
-
-    // 27.9.1.2 Constructors/destructor:
-    basic_filebuf();
-    basic_filebuf(basic_filebuf&& __rhs);
-    ~basic_filebuf() override;
-
-    // 27.9.1.3 Assign/swap:
-    _LIBCPP_INLINE_VISIBILITY
-    basic_filebuf& operator=(basic_filebuf&& __rhs);
-    void swap(basic_filebuf& __rhs);
-
-    // 27.9.1.4 Members:
-    _LIBCPP_INLINE_VISIBILITY
-    bool is_open() const;
-    basic_filebuf* open(const char* __s, ios_base::openmode __mode);
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
-    basic_filebuf* open(const wchar_t* __s, ios_base::openmode __mode);
-#endif
-    _LIBCPP_INLINE_VISIBILITY
-    basic_filebuf* open(const string& __s, ios_base::openmode __mode);
-
-#if _LIBCPP_STD_VER >= 17
-    _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_INLINE_VISIBILITY
-    basic_filebuf* open(const _VSTD_FS::path& __p, ios_base::openmode __mode) {
-      return open(__p.c_str(), __mode);
-    }
-#endif
-    _LIBCPP_INLINE_VISIBILITY
-    basic_filebuf* __open(int __fd, ios_base::openmode __mode);
-    basic_filebuf* close();
+  typedef _CharT char_type;
+  typedef _Traits traits_type;
+  typedef typename traits_type::int_type int_type;
+  typedef typename traits_type::pos_type pos_type;
+  typedef typename traits_type::off_type off_type;
+  typedef typename traits_type::state_type state_type;
+#  if _LIBCPP_STD_VER >= 26
+#    if defined(_LIBCPP_WIN32API)
+  using native_handle_type = void*; // HANDLE
+#    elif __has_include(<unistd.h>)
+  using native_handle_type = int; // POSIX file descriptor
+#    else
+#      error "Provide a native file handle!"
+#    endif
+#  endif
+
+  // 27.9.1.2 Constructors/destructor:
+  basic_filebuf();
+  basic_filebuf(basic_filebuf&& __rhs);
+  ~basic_filebuf() override;
+
+  // 27.9.1.3 Assign/swap:
+  _LIBCPP_HIDE_FROM_ABI basic_filebuf& operator=(basic_filebuf&& __rhs);
+  void swap(basic_filebuf& __rhs);
+
+  // 27.9.1.4 Members:
+  _LIBCPP_HIDE_FROM_ABI bool is_open() const;
+  basic_filebuf* open(const char* __s, ios_base::openmode __mode);
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+  basic_filebuf* open(const wchar_t* __s, ios_base::openmode __mode);
+#  endif
+  _LIBCPP_HIDE_FROM_ABI basic_filebuf* open(const string& __s, ios_base::openmode __mode);
+
+#  if _LIBCPP_STD_VER >= 17
+  _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_HIDE_FROM_ABI basic_filebuf*
+  open(const filesystem::path& __p, ios_base::openmode __mode) {
+    return open(__p.c_str(), __mode);
+  }
+#  endif
+  _LIBCPP_HIDE_FROM_ABI basic_filebuf* __open(int __fd, ios_base::openmode __mode);
+  basic_filebuf* close();
+#  if _LIBCPP_STD_VER >= 26
+  _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() const noexcept {
+    _LIBCPP_ASSERT_UNCATEGORIZED(this->is_open(), "File must be opened");
+#    if defined(_LIBCPP_WIN32API)
+    return std::__filebuf_windows_native_handle(__file_);
+#    elif __has_include(<unistd.h>)
+    return fileno(__file_);
+#    else
+#      error "Provide a way to determine the file native handle!"
+#    endif
+  }
+#  endif //  _LIBCPP_STD_VER >= 26
 
-    _LIBCPP_INLINE_VISIBILITY
-    inline static const char*
-    __make_mdstring(ios_base::openmode __mode) _NOEXCEPT;
+  _LIBCPP_HIDE_FROM_ABI inline static const char* __make_mdstring(ios_base::openmode __mode) _NOEXCEPT;
 
-  protected:
-    // 27.9.1.5 Overridden virtual functions:
-    int_type underflow() override;
-    int_type pbackfail(int_type __c = traits_type::eof()) override;
-    int_type overflow (int_type __c = traits_type::eof()) override;
-    basic_streambuf<char_type, traits_type>* setbuf(char_type* __s, streamsize __n) override;
-    pos_type seekoff(off_type __off, ios_base::seekdir __way,
-                     ios_base::openmode __wch = ios_base::in | ios_base::out) override;
-    pos_type seekpos(pos_type __sp,
-                     ios_base::openmode __wch = ios_base::in | ios_base::out) override;
-    int sync() override;
-    void imbue(const locale& __loc) override;
+protected:
+  // 27.9.1.5 Overridden virtual functions:
+  int_type underflow() override;
+  int_type pbackfail(int_type __c = traits_type::eof()) override;
+  int_type overflow(int_type __c = traits_type::eof()) override;
+  basic_streambuf<char_type, traits_type>* setbuf(char_type* __s, streamsize __n) override;
+  pos_type
+  seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode __wch = ios_base::in | ios_base::out) override;
+  pos_type seekpos(pos_type __sp, ios_base::openmode __wch = ios_base::in | ios_base::out) override;
+  int sync() override;
+  void imbue(const locale& __loc) override;
 
 private:
   char* __extbuf_;
@@ -289,6 +312,8 @@ private:
 
   bool __read_mode();
   void __write_mode();
+
+  _LIBCPP_EXPORTED_FROM_ABI friend FILE* __get_ostream_file(ostream&);
 };
 
 template <class _CharT, class _Traits>
@@ -307,220 +332,173 @@ basic_filebuf<_CharT, _Traits>::basic_filebuf()
       __cm_(0),
       __owns_eb_(false),
       __owns_ib_(false),
-      __always_noconv_(false)
-{
-    if (std::has_facet<codecvt<char_type, char, state_type> >(this->getloc()))
-    {
-        __cv_ = &std::use_facet<codecvt<char_type, char, state_type> >(this->getloc());
-        __always_noconv_ = __cv_->always_noconv();
-    }
-    setbuf(nullptr, 4096);
+      __always_noconv_(false) {
+  if (std::has_facet<codecvt<char_type, char, state_type> >(this->getloc())) {
+    __cv_            = &std::use_facet<codecvt<char_type, char, state_type> >(this->getloc());
+    __always_noconv_ = __cv_->always_noconv();
+  }
+  setbuf(nullptr, 4096);
 }
 
 template <class _CharT, class _Traits>
-basic_filebuf<_CharT, _Traits>::basic_filebuf(basic_filebuf&& __rhs)
-    : basic_streambuf<_CharT, _Traits>(__rhs)
-{
-    if (__rhs.__extbuf_ == __rhs.__extbuf_min_)
-    {
-        __extbuf_ = __extbuf_min_;
-        __extbufnext_ = __extbuf_ + (__rhs.__extbufnext_ - __rhs.__extbuf_);
-        __extbufend_ = __extbuf_ + (__rhs.__extbufend_ - __rhs.__extbuf_);
-    }
+basic_filebuf<_CharT, _Traits>::basic_filebuf(basic_filebuf&& __rhs) : basic_streambuf<_CharT, _Traits>(__rhs) {
+  if (__rhs.__extbuf_ == __rhs.__extbuf_min_) {
+    __extbuf_     = __extbuf_min_;
+    __extbufnext_ = __extbuf_ + (__rhs.__extbufnext_ - __rhs.__extbuf_);
+    __extbufend_  = __extbuf_ + (__rhs.__extbufend_ - __rhs.__extbuf_);
+  } else {
+    __extbuf_     = __rhs.__extbuf_;
+    __extbufnext_ = __rhs.__extbufnext_;
+    __extbufend_  = __rhs.__extbufend_;
+  }
+  __ebs_           = __rhs.__ebs_;
+  __intbuf_        = __rhs.__intbuf_;
+  __ibs_           = __rhs.__ibs_;
+  __file_          = __rhs.__file_;
+  __cv_            = __rhs.__cv_;
+  __st_            = __rhs.__st_;
+  __st_last_       = __rhs.__st_last_;
+  __om_            = __rhs.__om_;
+  __cm_            = __rhs.__cm_;
+  __owns_eb_       = __rhs.__owns_eb_;
+  __owns_ib_       = __rhs.__owns_ib_;
+  __always_noconv_ = __rhs.__always_noconv_;
+  if (__rhs.pbase()) {
+    if (__rhs.pbase() == __rhs.__intbuf_)
+      this->setp(__intbuf_, __intbuf_ + (__rhs.epptr() - __rhs.pbase()));
     else
-    {
-        __extbuf_ = __rhs.__extbuf_;
-        __extbufnext_ = __rhs.__extbufnext_;
-        __extbufend_ = __rhs.__extbufend_;
-    }
-    __ebs_ = __rhs.__ebs_;
-    __intbuf_ = __rhs.__intbuf_;
-    __ibs_ = __rhs.__ibs_;
-    __file_ = __rhs.__file_;
-    __cv_ = __rhs.__cv_;
-    __st_ = __rhs.__st_;
-    __st_last_ = __rhs.__st_last_;
-    __om_ = __rhs.__om_;
-    __cm_ = __rhs.__cm_;
-    __owns_eb_ = __rhs.__owns_eb_;
-    __owns_ib_ = __rhs.__owns_ib_;
-    __always_noconv_ = __rhs.__always_noconv_;
-    if (__rhs.pbase())
-    {
-        if (__rhs.pbase() == __rhs.__intbuf_)
-            this->setp(__intbuf_, __intbuf_ + (__rhs. epptr() - __rhs.pbase()));
-        else
-            this->setp((char_type*)__extbuf_,
-                       (char_type*)__extbuf_ + (__rhs. epptr() - __rhs.pbase()));
-        this->__pbump(__rhs. pptr() - __rhs.pbase());
-    }
-    else if (__rhs.eback())
-    {
-        if (__rhs.eback() == __rhs.__intbuf_)
-            this->setg(__intbuf_, __intbuf_ + (__rhs.gptr() - __rhs.eback()),
-                                  __intbuf_ + (__rhs.egptr() - __rhs.eback()));
-        else
-            this->setg((char_type*)__extbuf_,
-                       (char_type*)__extbuf_ + (__rhs.gptr() - __rhs.eback()),
-                       (char_type*)__extbuf_ + (__rhs.egptr() - __rhs.eback()));
-    }
-    __rhs.__extbuf_ = nullptr;
-    __rhs.__extbufnext_ = nullptr;
-    __rhs.__extbufend_ = nullptr;
-    __rhs.__ebs_ = 0;
-    __rhs.__intbuf_ = 0;
-    __rhs.__ibs_ = 0;
-    __rhs.__file_ = nullptr;
-    __rhs.__st_ = state_type();
-    __rhs.__st_last_ = state_type();
-    __rhs.__om_ = 0;
-    __rhs.__cm_ = 0;
-    __rhs.__owns_eb_ = false;
-    __rhs.__owns_ib_ = false;
-    __rhs.setg(0, 0, 0);
-    __rhs.setp(0, 0);
-}
-
-template <class _CharT, class _Traits>
-inline
-basic_filebuf<_CharT, _Traits>&
-basic_filebuf<_CharT, _Traits>::operator=(basic_filebuf&& __rhs)
-{
-    close();
-    swap(__rhs);
-    return *this;
-}
-
-template <class _CharT, class _Traits>
-basic_filebuf<_CharT, _Traits>::~basic_filebuf()
-{
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
-    try
-    {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
-        close();
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
-    }
-    catch (...)
-    {
-    }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
-    if (__owns_eb_)
-        delete [] __extbuf_;
-    if (__owns_ib_)
-        delete [] __intbuf_;
-}
-
-template <class _CharT, class _Traits>
-void
-basic_filebuf<_CharT, _Traits>::swap(basic_filebuf& __rhs)
-{
-    basic_streambuf<char_type, traits_type>::swap(__rhs);
-    if (__extbuf_ != __extbuf_min_ && __rhs.__extbuf_ != __rhs.__extbuf_min_)
-    {
-        // Neither *this nor __rhs uses the small buffer, so we can simply swap the pointers.
-        std::swap(__extbuf_, __rhs.__extbuf_);
-        std::swap(__extbufnext_, __rhs.__extbufnext_);
-        std::swap(__extbufend_, __rhs.__extbufend_);
-    }
+      this->setp((char_type*)__extbuf_, (char_type*)__extbuf_ + (__rhs.epptr() - __rhs.pbase()));
+    this->__pbump(__rhs.pptr() - __rhs.pbase());
+  } else if (__rhs.eback()) {
+    if (__rhs.eback() == __rhs.__intbuf_)
+      this->setg(__intbuf_, __intbuf_ + (__rhs.gptr() - __rhs.eback()), __intbuf_ + (__rhs.egptr() - __rhs.eback()));
     else
-    {
-        ptrdiff_t __ln = __extbufnext_       ? __extbufnext_ - __extbuf_             : 0;
-        ptrdiff_t __le = __extbufend_        ? __extbufend_ - __extbuf_              : 0;
-        ptrdiff_t __rn = __rhs.__extbufnext_ ? __rhs.__extbufnext_ - __rhs.__extbuf_ : 0;
-        ptrdiff_t __re = __rhs.__extbufend_  ? __rhs.__extbufend_ - __rhs.__extbuf_  : 0;
-        if (__extbuf_ == __extbuf_min_ && __rhs.__extbuf_ != __rhs.__extbuf_min_)
-        {
-            // *this uses the small buffer, but __rhs doesn't.
-            __extbuf_ = __rhs.__extbuf_;
-            __rhs.__extbuf_ = __rhs.__extbuf_min_;
-            std::memmove(__rhs.__extbuf_min_, __extbuf_min_, sizeof(__extbuf_min_));
-        }
-        else if (__extbuf_ != __extbuf_min_ && __rhs.__extbuf_ == __rhs.__extbuf_min_)
-        {
-            // *this doesn't use the small buffer, but __rhs does.
-            __rhs.__extbuf_ = __extbuf_;
-            __extbuf_ = __extbuf_min_;
-            std::memmove(__extbuf_min_, __rhs.__extbuf_min_, sizeof(__extbuf_min_));
-        }
-        else
-        {
-            // Both *this and __rhs use the small buffer.
-            char __tmp[sizeof(__extbuf_min_)];
-            std::memmove(__tmp, __extbuf_min_, sizeof(__extbuf_min_));
-            std::memmove(__extbuf_min_, __rhs.__extbuf_min_, sizeof(__extbuf_min_));
-            std::memmove(__rhs.__extbuf_min_, __tmp, sizeof(__extbuf_min_));
-        }
-        __extbufnext_ = __extbuf_ + __rn;
-        __extbufend_ = __extbuf_ + __re;
-        __rhs.__extbufnext_ = __rhs.__extbuf_ + __ln;
-        __rhs.__extbufend_ = __rhs.__extbuf_ + __le;
-    }
-    _VSTD::swap(__ebs_, __rhs.__ebs_);
-    _VSTD::swap(__intbuf_, __rhs.__intbuf_);
-    _VSTD::swap(__ibs_, __rhs.__ibs_);
-    _VSTD::swap(__file_, __rhs.__file_);
-    _VSTD::swap(__cv_, __rhs.__cv_);
-    _VSTD::swap(__st_, __rhs.__st_);
-    _VSTD::swap(__st_last_, __rhs.__st_last_);
-    _VSTD::swap(__om_, __rhs.__om_);
-    _VSTD::swap(__cm_, __rhs.__cm_);
-    _VSTD::swap(__owns_eb_, __rhs.__owns_eb_);
-    _VSTD::swap(__owns_ib_, __rhs.__owns_ib_);
-    _VSTD::swap(__always_noconv_, __rhs.__always_noconv_);
-    if (this->eback() == (char_type*)__rhs.__extbuf_min_)
-    {
-        ptrdiff_t __n = this->gptr() - this->eback();
-        ptrdiff_t __e = this->egptr() - this->eback();
-        this->setg((char_type*)__extbuf_min_,
-                   (char_type*)__extbuf_min_ + __n,
-                   (char_type*)__extbuf_min_ + __e);
-    }
-    else if (this->pbase() == (char_type*)__rhs.__extbuf_min_)
-    {
-        ptrdiff_t __n = this->pptr() - this->pbase();
-        ptrdiff_t __e = this->epptr() - this->pbase();
-        this->setp((char_type*)__extbuf_min_,
-                   (char_type*)__extbuf_min_ + __e);
-        this->__pbump(__n);
-    }
-    if (__rhs.eback() == (char_type*)__extbuf_min_)
-    {
-        ptrdiff_t __n = __rhs.gptr() - __rhs.eback();
-        ptrdiff_t __e = __rhs.egptr() - __rhs.eback();
-        __rhs.setg((char_type*)__rhs.__extbuf_min_,
-                   (char_type*)__rhs.__extbuf_min_ + __n,
-                   (char_type*)__rhs.__extbuf_min_ + __e);
-    }
-    else if (__rhs.pbase() == (char_type*)__extbuf_min_)
-    {
-        ptrdiff_t __n = __rhs.pptr() - __rhs.pbase();
-        ptrdiff_t __e = __rhs.epptr() - __rhs.pbase();
-        __rhs.setp((char_type*)__rhs.__extbuf_min_,
-                   (char_type*)__rhs.__extbuf_min_ + __e);
-        __rhs.__pbump(__n);
+      this->setg((char_type*)__extbuf_,
+                 (char_type*)__extbuf_ + (__rhs.gptr() - __rhs.eback()),
+                 (char_type*)__extbuf_ + (__rhs.egptr() - __rhs.eback()));
+  }
+  __rhs.__extbuf_     = nullptr;
+  __rhs.__extbufnext_ = nullptr;
+  __rhs.__extbufend_  = nullptr;
+  __rhs.__ebs_        = 0;
+  __rhs.__intbuf_     = 0;
+  __rhs.__ibs_        = 0;
+  __rhs.__file_       = nullptr;
+  __rhs.__st_         = state_type();
+  __rhs.__st_last_    = state_type();
+  __rhs.__om_         = 0;
+  __rhs.__cm_         = 0;
+  __rhs.__owns_eb_    = false;
+  __rhs.__owns_ib_    = false;
+  __rhs.setg(0, 0, 0);
+  __rhs.setp(0, 0);
+}
+
+template <class _CharT, class _Traits>
+inline basic_filebuf<_CharT, _Traits>& basic_filebuf<_CharT, _Traits>::operator=(basic_filebuf&& __rhs) {
+  close();
+  swap(__rhs);
+  return *this;
+}
+
+template <class _CharT, class _Traits>
+basic_filebuf<_CharT, _Traits>::~basic_filebuf() {
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+  try {
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
+    close();
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+  } catch (...) {
+  }
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
+  if (__owns_eb_)
+    delete[] __extbuf_;
+  if (__owns_ib_)
+    delete[] __intbuf_;
+}
+
+template <class _CharT, class _Traits>
+void basic_filebuf<_CharT, _Traits>::swap(basic_filebuf& __rhs) {
+  basic_streambuf<char_type, traits_type>::swap(__rhs);
+  if (__extbuf_ != __extbuf_min_ && __rhs.__extbuf_ != __rhs.__extbuf_min_) {
+    // Neither *this nor __rhs uses the small buffer, so we can simply swap the pointers.
+    std::swap(__extbuf_, __rhs.__extbuf_);
+    std::swap(__extbufnext_, __rhs.__extbufnext_);
+    std::swap(__extbufend_, __rhs.__extbufend_);
+  } else {
+    ptrdiff_t __ln = __extbufnext_ ? __extbufnext_ - __extbuf_ : 0;
+    ptrdiff_t __le = __extbufend_ ? __extbufend_ - __extbuf_ : 0;
+    ptrdiff_t __rn = __rhs.__extbufnext_ ? __rhs.__extbufnext_ - __rhs.__extbuf_ : 0;
+    ptrdiff_t __re = __rhs.__extbufend_ ? __rhs.__extbufend_ - __rhs.__extbuf_ : 0;
+    if (__extbuf_ == __extbuf_min_ && __rhs.__extbuf_ != __rhs.__extbuf_min_) {
+      // *this uses the small buffer, but __rhs doesn't.
+      __extbuf_       = __rhs.__extbuf_;
+      __rhs.__extbuf_ = __rhs.__extbuf_min_;
+      std::memmove(__rhs.__extbuf_min_, __extbuf_min_, sizeof(__extbuf_min_));
+    } else if (__extbuf_ != __extbuf_min_ && __rhs.__extbuf_ == __rhs.__extbuf_min_) {
+      // *this doesn't use the small buffer, but __rhs does.
+      __rhs.__extbuf_ = __extbuf_;
+      __extbuf_       = __extbuf_min_;
+      std::memmove(__extbuf_min_, __rhs.__extbuf_min_, sizeof(__extbuf_min_));
+    } else {
+      // Both *this and __rhs use the small buffer.
+      char __tmp[sizeof(__extbuf_min_)];
+      std::memmove(__tmp, __extbuf_min_, sizeof(__extbuf_min_));
+      std::memmove(__extbuf_min_, __rhs.__extbuf_min_, sizeof(__extbuf_min_));
+      std::memmove(__rhs.__extbuf_min_, __tmp, sizeof(__extbuf_min_));
     }
+    __extbufnext_       = __extbuf_ + __rn;
+    __extbufend_        = __extbuf_ + __re;
+    __rhs.__extbufnext_ = __rhs.__extbuf_ + __ln;
+    __rhs.__extbufend_  = __rhs.__extbuf_ + __le;
+  }
+  std::swap(__ebs_, __rhs.__ebs_);
+  std::swap(__intbuf_, __rhs.__intbuf_);
+  std::swap(__ibs_, __rhs.__ibs_);
+  std::swap(__file_, __rhs.__file_);
+  std::swap(__cv_, __rhs.__cv_);
+  std::swap(__st_, __rhs.__st_);
+  std::swap(__st_last_, __rhs.__st_last_);
+  std::swap(__om_, __rhs.__om_);
+  std::swap(__cm_, __rhs.__cm_);
+  std::swap(__owns_eb_, __rhs.__owns_eb_);
+  std::swap(__owns_ib_, __rhs.__owns_ib_);
+  std::swap(__always_noconv_, __rhs.__always_noconv_);
+  if (this->eback() == (char_type*)__rhs.__extbuf_min_) {
+    ptrdiff_t __n = this->gptr() - this->eback();
+    ptrdiff_t __e = this->egptr() - this->eback();
+    this->setg((char_type*)__extbuf_min_, (char_type*)__extbuf_min_ + __n, (char_type*)__extbuf_min_ + __e);
+  } else if (this->pbase() == (char_type*)__rhs.__extbuf_min_) {
+    ptrdiff_t __n = this->pptr() - this->pbase();
+    ptrdiff_t __e = this->epptr() - this->pbase();
+    this->setp((char_type*)__extbuf_min_, (char_type*)__extbuf_min_ + __e);
+    this->__pbump(__n);
+  }
+  if (__rhs.eback() == (char_type*)__extbuf_min_) {
+    ptrdiff_t __n = __rhs.gptr() - __rhs.eback();
+    ptrdiff_t __e = __rhs.egptr() - __rhs.eback();
+    __rhs.setg(
+        (char_type*)__rhs.__extbuf_min_, (char_type*)__rhs.__extbuf_min_ + __n, (char_type*)__rhs.__extbuf_min_ + __e);
+  } else if (__rhs.pbase() == (char_type*)__extbuf_min_) {
+    ptrdiff_t __n = __rhs.pptr() - __rhs.pbase();
+    ptrdiff_t __e = __rhs.epptr() - __rhs.pbase();
+    __rhs.setp((char_type*)__rhs.__extbuf_min_, (char_type*)__rhs.__extbuf_min_ + __e);
+    __rhs.__pbump(__n);
+  }
 }
 
 template <class _CharT, class _Traits>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-swap(basic_filebuf<_CharT, _Traits>& __x, basic_filebuf<_CharT, _Traits>& __y)
-{
-    __x.swap(__y);
+inline _LIBCPP_HIDE_FROM_ABI void swap(basic_filebuf<_CharT, _Traits>& __x, basic_filebuf<_CharT, _Traits>& __y) {
+  __x.swap(__y);
 }
 
 template <class _CharT, class _Traits>
-inline
-bool
-basic_filebuf<_CharT, _Traits>::is_open() const
-{
-    return __file_ != nullptr;
+inline bool basic_filebuf<_CharT, _Traits>::is_open() const {
+  return __file_ != nullptr;
 }
 
 template <class _CharT, class _Traits>
-const char* basic_filebuf<_CharT, _Traits>::__make_mdstring(
-    ios_base::openmode __mode) _NOEXCEPT {
+const char* basic_filebuf<_CharT, _Traits>::__make_mdstring(ios_base::openmode __mode) _NOEXCEPT {
   switch (__mode & ~ios_base::ate) {
   case ios_base::out:
   case ios_base::out | ios_base::trunc:
@@ -552,6 +530,18 @@ const char* basic_filebuf<_CharT, _Traits>::__make_mdstring(
   case ios_base::in | ios_base::out | ios_base::app | ios_base::binary:
   case ios_base::in | ios_base::app | ios_base::binary:
     return "a+b" _LIBCPP_FOPEN_CLOEXEC_MODE;
+#  if _LIBCPP_STD_VER >= 23
+  case ios_base::out | ios_base::noreplace:
+  case ios_base::out | ios_base::trunc | ios_base::noreplace:
+    return "wx" _LIBCPP_FOPEN_CLOEXEC_MODE;
+  case ios_base::in | ios_base::out | ios_base::trunc | ios_base::noreplace:
+    return "w+x" _LIBCPP_FOPEN_CLOEXEC_MODE;
+  case ios_base::out | ios_base::binary | ios_base::noreplace:
+  case ios_base::out | ios_base::trunc | ios_base::binary | ios_base::noreplace:
+    return "wbx" _LIBCPP_FOPEN_CLOEXEC_MODE;
+  case ios_base::in | ios_base::out | ios_base::trunc | ios_base::binary | ios_base::noreplace:
+    return "w+bx" _LIBCPP_FOPEN_CLOEXEC_MODE;
+#  endif // _LIBCPP_STD_VER >= 23
   default:
     return nullptr;
   }
@@ -559,39 +549,34 @@ const char* basic_filebuf<_CharT, _Traits>::__make_mdstring(
 }
 
 template <class _CharT, class _Traits>
-basic_filebuf<_CharT, _Traits>*
-basic_filebuf<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode)
-{
-    basic_filebuf<_CharT, _Traits>* __rt = nullptr;
-    if (__file_ == nullptr)
-    {
-      if (const char* __mdstr = __make_mdstring(__mode)) {
-        __rt = this;
-        __file_ = fopen(__s, __mdstr);
-        if (__file_) {
-          __om_ = __mode;
-          if (__mode & ios_base::ate) {
-            if (fseek(__file_, 0, SEEK_END)) {
-              fclose(__file_);
-              __file_ = nullptr;
-              __rt = nullptr;
-            }
+basic_filebuf<_CharT, _Traits>* basic_filebuf<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode) {
+  basic_filebuf<_CharT, _Traits>* __rt = nullptr;
+  if (__file_ == nullptr) {
+    if (const char* __mdstr = __make_mdstring(__mode)) {
+      __rt    = this;
+      __file_ = fopen(__s, __mdstr);
+      if (__file_) {
+        __om_ = __mode;
+        if (__mode & ios_base::ate) {
+          if (fseek(__file_, 0, SEEK_END)) {
+            fclose(__file_);
+            __file_ = nullptr;
+            __rt    = nullptr;
           }
-        } else
-          __rt = nullptr;
-      }
+        }
+      } else
+        __rt = nullptr;
     }
-    return __rt;
+  }
+  return __rt;
 }
 
 template <class _CharT, class _Traits>
-inline
-basic_filebuf<_CharT, _Traits>*
-basic_filebuf<_CharT, _Traits>::__open(int __fd, ios_base::openmode __mode) {
+inline basic_filebuf<_CharT, _Traits>* basic_filebuf<_CharT, _Traits>::__open(int __fd, ios_base::openmode __mode) {
   basic_filebuf<_CharT, _Traits>* __rt = nullptr;
   if (__file_ == nullptr) {
     if (const char* __mdstr = __make_mdstring(__mode)) {
-      __rt = this;
+      __rt    = this;
       __file_ = fdopen(__fd, __mdstr);
       if (__file_) {
         __om_ = __mode;
@@ -599,7 +584,7 @@ basic_filebuf<_CharT, _Traits>::__open(int __fd, ios_base::openmode __mode) {
           if (fseek(__file_, 0, SEEK_END)) {
             fclose(__file_);
             __file_ = nullptr;
-            __rt = nullptr;
+            __rt    = nullptr;
           }
         }
       } else
@@ -609,724 +594,599 @@ basic_filebuf<_CharT, _Traits>::__open(int __fd, ios_base::openmode __mode) {
   return __rt;
 }
 
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
 // This is basically the same as the char* overload except that it uses _wfopen
 // and long mode strings.
 template <class _CharT, class _Traits>
-basic_filebuf<_CharT, _Traits>*
-basic_filebuf<_CharT, _Traits>::open(const wchar_t* __s, ios_base::openmode __mode)
-{
-    basic_filebuf<_CharT, _Traits>* __rt = nullptr;
-    if (__file_ == nullptr)
-    {
-        __rt = this;
-        const wchar_t* __mdstr;
-        switch (__mode & ~ios_base::ate)
-        {
-        case ios_base::out:
-        case ios_base::out | ios_base::trunc:
-            __mdstr = L"w";
-            break;
-        case ios_base::out | ios_base::app:
-        case ios_base::app:
-            __mdstr = L"a";
-            break;
-        case ios_base::in:
-            __mdstr = L"r";
-            break;
-        case ios_base::in | ios_base::out:
-            __mdstr = L"r+";
-            break;
-        case ios_base::in | ios_base::out | ios_base::trunc:
-            __mdstr = L"w+";
-            break;
-        case ios_base::in | ios_base::out | ios_base::app:
-        case ios_base::in | ios_base::app:
-            __mdstr = L"a+";
-            break;
-        case ios_base::out | ios_base::binary:
-        case ios_base::out | ios_base::trunc | ios_base::binary:
-            __mdstr = L"wb";
-            break;
-        case ios_base::out | ios_base::app | ios_base::binary:
-        case ios_base::app | ios_base::binary:
-            __mdstr = L"ab";
-            break;
-        case ios_base::in | ios_base::binary:
-            __mdstr = L"rb";
-            break;
-        case ios_base::in | ios_base::out | ios_base::binary:
-            __mdstr = L"r+b";
-            break;
-        case ios_base::in | ios_base::out | ios_base::trunc | ios_base::binary:
-            __mdstr = L"w+b";
-            break;
-        case ios_base::in | ios_base::out | ios_base::app | ios_base::binary:
-        case ios_base::in | ios_base::app | ios_base::binary:
-            __mdstr = L"a+b";
-            break;
-        default:
-            __rt = nullptr;
-            break;
-        }
-        if (__rt)
-        {
-            __file_ = _wfopen(__s, __mdstr);
-            if (__file_)
-            {
-                __om_ = __mode;
-                if (__mode & ios_base::ate)
-                {
-                    if (fseek(__file_, 0, SEEK_END))
-                    {
-                        fclose(__file_);
-                        __file_ = nullptr;
-                        __rt = nullptr;
-                    }
-                }
-            }
-            else
-                __rt = nullptr;
+basic_filebuf<_CharT, _Traits>* basic_filebuf<_CharT, _Traits>::open(const wchar_t* __s, ios_base::openmode __mode) {
+  basic_filebuf<_CharT, _Traits>* __rt = nullptr;
+  if (__file_ == nullptr) {
+    __rt = this;
+    const wchar_t* __mdstr;
+    switch (__mode & ~ios_base::ate) {
+    case ios_base::out:
+    case ios_base::out | ios_base::trunc:
+      __mdstr = L"w";
+      break;
+    case ios_base::out | ios_base::app:
+    case ios_base::app:
+      __mdstr = L"a";
+      break;
+    case ios_base::in:
+      __mdstr = L"r";
+      break;
+    case ios_base::in | ios_base::out:
+      __mdstr = L"r+";
+      break;
+    case ios_base::in | ios_base::out | ios_base::trunc:
+      __mdstr = L"w+";
+      break;
+    case ios_base::in | ios_base::out | ios_base::app:
+    case ios_base::in | ios_base::app:
+      __mdstr = L"a+";
+      break;
+    case ios_base::out | ios_base::binary:
+    case ios_base::out | ios_base::trunc | ios_base::binary:
+      __mdstr = L"wb";
+      break;
+    case ios_base::out | ios_base::app | ios_base::binary:
+    case ios_base::app | ios_base::binary:
+      __mdstr = L"ab";
+      break;
+    case ios_base::in | ios_base::binary:
+      __mdstr = L"rb";
+      break;
+    case ios_base::in | ios_base::out | ios_base::binary:
+      __mdstr = L"r+b";
+      break;
+    case ios_base::in | ios_base::out | ios_base::trunc | ios_base::binary:
+      __mdstr = L"w+b";
+      break;
+    case ios_base::in | ios_base::out | ios_base::app | ios_base::binary:
+    case ios_base::in | ios_base::app | ios_base::binary:
+      __mdstr = L"a+b";
+      break;
+#    if _LIBCPP_STD_VER >= 23
+    case ios_base::out | ios_base::noreplace:
+    case ios_base::out | ios_base::trunc | ios_base::noreplace:
+      __mdstr = L"wx";
+      break;
+    case ios_base::in | ios_base::out | ios_base::trunc | ios_base::noreplace:
+      __mdstr = L"w+x";
+      break;
+    case ios_base::out | ios_base::binary | ios_base::noreplace:
+    case ios_base::out | ios_base::trunc | ios_base::binary | ios_base::noreplace:
+      __mdstr = L"wbx";
+      break;
+    case ios_base::in | ios_base::out | ios_base::trunc | ios_base::binary | ios_base::noreplace:
+      __mdstr = L"w+bx";
+      break;
+#    endif // _LIBCPP_STD_VER >= 23
+    default:
+      __rt = nullptr;
+      break;
+    }
+    if (__rt) {
+      __file_ = _wfopen(__s, __mdstr);
+      if (__file_) {
+        __om_ = __mode;
+        if (__mode & ios_base::ate) {
+          if (fseek(__file_, 0, SEEK_END)) {
+            fclose(__file_);
+            __file_ = nullptr;
+            __rt    = nullptr;
+          }
         }
+      } else
+        __rt = nullptr;
     }
-    return __rt;
+  }
+  return __rt;
 }
-#endif
+#  endif
 
 template <class _CharT, class _Traits>
-inline
-basic_filebuf<_CharT, _Traits>*
-basic_filebuf<_CharT, _Traits>::open(const string& __s, ios_base::openmode __mode)
-{
-    return open(__s.c_str(), __mode);
+inline basic_filebuf<_CharT, _Traits>*
+basic_filebuf<_CharT, _Traits>::open(const string& __s, ios_base::openmode __mode) {
+  return open(__s.c_str(), __mode);
 }
 
 template <class _CharT, class _Traits>
-basic_filebuf<_CharT, _Traits>*
-basic_filebuf<_CharT, _Traits>::close()
-{
-    basic_filebuf<_CharT, _Traits>* __rt = nullptr;
-    if (__file_)
-    {
-        __rt = this;
-        unique_ptr<FILE, int(*)(FILE*)> __h(__file_, fclose);
-        if (sync())
-            __rt = nullptr;
-        if (fclose(__h.release()))
-            __rt = nullptr;
-        __file_ = nullptr;
-        setbuf(0, 0);
-    }
-    return __rt;
+basic_filebuf<_CharT, _Traits>* basic_filebuf<_CharT, _Traits>::close() {
+  basic_filebuf<_CharT, _Traits>* __rt = nullptr;
+  if (__file_) {
+    __rt = this;
+    unique_ptr<FILE, int (*)(FILE*)> __h(__file_, fclose);
+    if (sync())
+      __rt = nullptr;
+    if (fclose(__h.release()))
+      __rt = nullptr;
+    __file_ = nullptr;
+    setbuf(0, 0);
+  }
+  return __rt;
 }
 
 template <class _CharT, class _Traits>
-typename basic_filebuf<_CharT, _Traits>::int_type
-basic_filebuf<_CharT, _Traits>::underflow()
-{
-    if (__file_ == nullptr)
-        return traits_type::eof();
-    bool __initial = __read_mode();
-    char_type __1buf;
-    if (this->gptr() == nullptr)
-        this->setg(&__1buf, &__1buf+1, &__1buf+1);
-    const size_t __unget_sz = __initial ? 0 : std::min<size_t>((this->egptr() - this->eback()) / 2, 4);
-    int_type __c = traits_type::eof();
-    if (this->gptr() == this->egptr())
-    {
-        _VSTD::memmove(this->eback(), this->egptr() - __unget_sz, __unget_sz * sizeof(char_type));
-        if (__always_noconv_)
-        {
-            size_t __nmemb = static_cast<size_t>(this->egptr() - this->eback() - __unget_sz);
-            __nmemb = ::fread(this->eback() + __unget_sz, 1, __nmemb, __file_);
-            if (__nmemb != 0)
-            {
-                this->setg(this->eback(),
-                           this->eback() + __unget_sz,
-                           this->eback() + __unget_sz + __nmemb);
-                __c = traits_type::to_int_type(*this->gptr());
-            }
-        }
-        else
-        {
-            if (__extbufend_ != __extbufnext_) {
-                _LIBCPP_ASSERT_UNCATEGORIZED(__extbufnext_ != nullptr, "underflow moving from nullptr");
-                _LIBCPP_ASSERT_UNCATEGORIZED(__extbuf_ != nullptr, "underflow moving into nullptr");
-                _VSTD::memmove(__extbuf_, __extbufnext_, __extbufend_ - __extbufnext_);
-            }
-            __extbufnext_ = __extbuf_ + (__extbufend_ - __extbufnext_);
-            __extbufend_ = __extbuf_ + (__extbuf_ == __extbuf_min_ ? sizeof(__extbuf_min_) : __ebs_);
-            size_t __nmemb = _VSTD::min(static_cast<size_t>(__ibs_ - __unget_sz),
-                                 static_cast<size_t>(__extbufend_ - __extbufnext_));
-            codecvt_base::result __r;
-            __st_last_ = __st_;
-            size_t __nr = fread((void*) const_cast<char *>(__extbufnext_), 1, __nmemb, __file_);
-            if (__nr != 0)
-            {
-                if (!__cv_)
-                    __throw_bad_cast();
-
-                __extbufend_ = __extbufnext_ + __nr;
-                char_type*  __inext;
-                __r = __cv_->in(__st_, __extbuf_, __extbufend_, __extbufnext_,
-                                       this->eback() + __unget_sz,
-                                       this->eback() + __ibs_, __inext);
-                if (__r == codecvt_base::noconv)
-                {
-                    this->setg((char_type*)__extbuf_, (char_type*)__extbuf_,
-                                          (char_type*)const_cast<char *>(__extbufend_));
-                    __c = traits_type::to_int_type(*this->gptr());
-                }
-                else if (__inext != this->eback() + __unget_sz)
-                {
-                    this->setg(this->eback(), this->eback() + __unget_sz, __inext);
-                    __c = traits_type::to_int_type(*this->gptr());
-                }
-            }
-        }
-    }
-    else
+typename basic_filebuf<_CharT, _Traits>::int_type basic_filebuf<_CharT, _Traits>::underflow() {
+  if (__file_ == nullptr)
+    return traits_type::eof();
+  bool __initial = __read_mode();
+  char_type __1buf;
+  if (this->gptr() == nullptr)
+    this->setg(&__1buf, &__1buf + 1, &__1buf + 1);
+  const size_t __unget_sz = __initial ? 0 : std::min<size_t>((this->egptr() - this->eback()) / 2, 4);
+  int_type __c            = traits_type::eof();
+  if (this->gptr() == this->egptr()) {
+    std::memmove(this->eback(), this->egptr() - __unget_sz, __unget_sz * sizeof(char_type));
+    if (__always_noconv_) {
+      size_t __nmemb = static_cast<size_t>(this->egptr() - this->eback() - __unget_sz);
+      __nmemb        = ::fread(this->eback() + __unget_sz, 1, __nmemb, __file_);
+      if (__nmemb != 0) {
+        this->setg(this->eback(), this->eback() + __unget_sz, this->eback() + __unget_sz + __nmemb);
         __c = traits_type::to_int_type(*this->gptr());
-    if (this->eback() == &__1buf)
-        this->setg(nullptr, nullptr, nullptr);
-    return __c;
-}
-
-template <class _CharT, class _Traits>
-typename basic_filebuf<_CharT, _Traits>::int_type
-basic_filebuf<_CharT, _Traits>::pbackfail(int_type __c)
-{
-    if (__file_ && this->eback() < this->gptr())
-    {
-        if (traits_type::eq_int_type(__c, traits_type::eof()))
-        {
-            this->gbump(-1);
-            return traits_type::not_eof(__c);
-        }
-        if ((__om_ & ios_base::out) ||
-            traits_type::eq(traits_type::to_char_type(__c), this->gptr()[-1]))
-        {
-            this->gbump(-1);
-            *this->gptr() = traits_type::to_char_type(__c);
-            return __c;
+      }
+    } else {
+      if (__extbufend_ != __extbufnext_) {
+        _LIBCPP_ASSERT_NON_NULL(__extbufnext_ != nullptr, "underflow moving from nullptr");
+        _LIBCPP_ASSERT_NON_NULL(__extbuf_ != nullptr, "underflow moving into nullptr");
+        std::memmove(__extbuf_, __extbufnext_, __extbufend_ - __extbufnext_);
+      }
+      __extbufnext_ = __extbuf_ + (__extbufend_ - __extbufnext_);
+      __extbufend_  = __extbuf_ + (__extbuf_ == __extbuf_min_ ? sizeof(__extbuf_min_) : __ebs_);
+      size_t __nmemb =
+          std::min(static_cast<size_t>(__ibs_ - __unget_sz), static_cast<size_t>(__extbufend_ - __extbufnext_));
+      codecvt_base::result __r;
+      __st_last_  = __st_;
+      size_t __nr = fread((void*)const_cast<char*>(__extbufnext_), 1, __nmemb, __file_);
+      if (__nr != 0) {
+        if (!__cv_)
+          __throw_bad_cast();
+
+        __extbufend_ = __extbufnext_ + __nr;
+        char_type* __inext;
+        __r = __cv_->in(
+            __st_, __extbuf_, __extbufend_, __extbufnext_, this->eback() + __unget_sz, this->eback() + __ibs_, __inext);
+        if (__r == codecvt_base::noconv) {
+          this->setg((char_type*)__extbuf_, (char_type*)__extbuf_, (char_type*)const_cast<char*>(__extbufend_));
+          __c = traits_type::to_int_type(*this->gptr());
+        } else if (__inext != this->eback() + __unget_sz) {
+          this->setg(this->eback(), this->eback() + __unget_sz, __inext);
+          __c = traits_type::to_int_type(*this->gptr());
         }
+      }
     }
-    return traits_type::eof();
+  } else
+    __c = traits_type::to_int_type(*this->gptr());
+  if (this->eback() == &__1buf)
+    this->setg(nullptr, nullptr, nullptr);
+  return __c;
 }
 
 template <class _CharT, class _Traits>
-typename basic_filebuf<_CharT, _Traits>::int_type
-basic_filebuf<_CharT, _Traits>::overflow(int_type __c)
-{
-    if (__file_ == nullptr)
-        return traits_type::eof();
-    __write_mode();
-    char_type __1buf;
-    char_type* __pb_save = this->pbase();
-    char_type* __epb_save = this->epptr();
-    if (!traits_type::eq_int_type(__c, traits_type::eof()))
-    {
-        if (this->pptr() == nullptr)
-            this->setp(&__1buf, &__1buf+1);
-        *this->pptr() = traits_type::to_char_type(__c);
-        this->pbump(1);
+typename basic_filebuf<_CharT, _Traits>::int_type basic_filebuf<_CharT, _Traits>::pbackfail(int_type __c) {
+  if (__file_ && this->eback() < this->gptr()) {
+    if (traits_type::eq_int_type(__c, traits_type::eof())) {
+      this->gbump(-1);
+      return traits_type::not_eof(__c);
     }
-    if (this->pptr() != this->pbase())
-    {
-        if (__always_noconv_)
-        {
-            size_t __nmemb = static_cast<size_t>(this->pptr() - this->pbase());
-            if (std::fwrite(this->pbase(), sizeof(char_type), __nmemb, __file_) != __nmemb)
-                return traits_type::eof();
-        }
-        else
-        {
-            char* __extbe = __extbuf_;
-            codecvt_base::result __r;
-            do
-            {
-                if (!__cv_)
-                    __throw_bad_cast();
-
-                const char_type* __e;
-                __r = __cv_->out(__st_, this->pbase(), this->pptr(), __e,
-                                        __extbuf_, __extbuf_ + __ebs_, __extbe);
-                if (__e == this->pbase())
-                    return traits_type::eof();
-                if (__r == codecvt_base::noconv)
-                {
-                    size_t __nmemb = static_cast<size_t>(this->pptr() - this->pbase());
-                    if (std::fwrite(this->pbase(), 1, __nmemb, __file_) != __nmemb)
-                        return traits_type::eof();
-                }
-                else if (__r == codecvt_base::ok || __r == codecvt_base::partial)
-                {
-                    size_t __nmemb = static_cast<size_t>(__extbe - __extbuf_);
-                    if (fwrite(__extbuf_, 1, __nmemb, __file_) != __nmemb)
-                        return traits_type::eof();
-                    if (__r == codecvt_base::partial)
-                    {
-                        this->setp(const_cast<char_type*>(__e), this->pptr());
-                        this->__pbump(this->epptr() - this->pbase());
-                    }
-                }
-                else
-                    return traits_type::eof();
-            } while (__r == codecvt_base::partial);
-        }
-        this->setp(__pb_save, __epb_save);
+    if ((__om_ & ios_base::out) || traits_type::eq(traits_type::to_char_type(__c), this->gptr()[-1])) {
+      this->gbump(-1);
+      *this->gptr() = traits_type::to_char_type(__c);
+      return __c;
     }
-    return traits_type::not_eof(__c);
+  }
+  return traits_type::eof();
 }
 
 template <class _CharT, class _Traits>
-basic_streambuf<_CharT, _Traits>*
-basic_filebuf<_CharT, _Traits>::setbuf(char_type* __s, streamsize __n)
-{
-    this->setg(nullptr, nullptr, nullptr);
-    this->setp(nullptr, nullptr);
-    if (__owns_eb_)
-        delete [] __extbuf_;
-    if (__owns_ib_)
-        delete [] __intbuf_;
-    __ebs_ = __n;
-    if (__ebs_ > sizeof(__extbuf_min_))
-    {
-        if (__always_noconv_ && __s)
-        {
-            __extbuf_ = (char*)__s;
-            __owns_eb_ = false;
-        }
-        else
-        {
-            __extbuf_ = new char[__ebs_];
-            __owns_eb_ = true;
-        }
-    }
-    else
-    {
-        __extbuf_ = __extbuf_min_;
-        __ebs_ = sizeof(__extbuf_min_);
-        __owns_eb_ = false;
+typename basic_filebuf<_CharT, _Traits>::int_type basic_filebuf<_CharT, _Traits>::overflow(int_type __c) {
+  if (__file_ == nullptr)
+    return traits_type::eof();
+  __write_mode();
+  char_type __1buf;
+  char_type* __pb_save  = this->pbase();
+  char_type* __epb_save = this->epptr();
+  if (!traits_type::eq_int_type(__c, traits_type::eof())) {
+    if (this->pptr() == nullptr)
+      this->setp(&__1buf, &__1buf + 1);
+    *this->pptr() = traits_type::to_char_type(__c);
+    this->pbump(1);
+  }
+  if (this->pptr() != this->pbase()) {
+    if (__always_noconv_) {
+      size_t __nmemb = static_cast<size_t>(this->pptr() - this->pbase());
+      if (std::fwrite(this->pbase(), sizeof(char_type), __nmemb, __file_) != __nmemb)
+        return traits_type::eof();
+    } else {
+      char* __extbe = __extbuf_;
+      codecvt_base::result __r;
+      do {
+        if (!__cv_)
+          __throw_bad_cast();
+
+        const char_type* __e;
+        __r = __cv_->out(__st_, this->pbase(), this->pptr(), __e, __extbuf_, __extbuf_ + __ebs_, __extbe);
+        if (__e == this->pbase())
+          return traits_type::eof();
+        if (__r == codecvt_base::noconv) {
+          size_t __nmemb = static_cast<size_t>(this->pptr() - this->pbase());
+          if (std::fwrite(this->pbase(), 1, __nmemb, __file_) != __nmemb)
+            return traits_type::eof();
+        } else if (__r == codecvt_base::ok || __r == codecvt_base::partial) {
+          size_t __nmemb = static_cast<size_t>(__extbe - __extbuf_);
+          if (fwrite(__extbuf_, 1, __nmemb, __file_) != __nmemb)
+            return traits_type::eof();
+          if (__r == codecvt_base::partial) {
+            this->setp(const_cast<char_type*>(__e), this->pptr());
+            this->__pbump(this->epptr() - this->pbase());
+          }
+        } else
+          return traits_type::eof();
+      } while (__r == codecvt_base::partial);
     }
-    if (!__always_noconv_)
-    {
-        __ibs_ = max<streamsize>(__n, sizeof(__extbuf_min_));
-        if (__s && __ibs_ >= sizeof(__extbuf_min_))
-        {
-            __intbuf_ = __s;
-            __owns_ib_ = false;
-        }
-        else
-        {
-            __intbuf_ = new char_type[__ibs_];
-            __owns_ib_ = true;
-        }
+    this->setp(__pb_save, __epb_save);
+  }
+  return traits_type::not_eof(__c);
+}
+
+template <class _CharT, class _Traits>
+basic_streambuf<_CharT, _Traits>* basic_filebuf<_CharT, _Traits>::setbuf(char_type* __s, streamsize __n) {
+  this->setg(nullptr, nullptr, nullptr);
+  this->setp(nullptr, nullptr);
+  if (__owns_eb_)
+    delete[] __extbuf_;
+  if (__owns_ib_)
+    delete[] __intbuf_;
+  __ebs_ = __n;
+  if (__ebs_ > sizeof(__extbuf_min_)) {
+    if (__always_noconv_ && __s) {
+      __extbuf_  = (char*)__s;
+      __owns_eb_ = false;
+    } else {
+      __extbuf_  = new char[__ebs_];
+      __owns_eb_ = true;
     }
-    else
-    {
-        __ibs_ = 0;
-        __intbuf_ = nullptr;
-        __owns_ib_ = false;
+  } else {
+    __extbuf_  = __extbuf_min_;
+    __ebs_     = sizeof(__extbuf_min_);
+    __owns_eb_ = false;
+  }
+  if (!__always_noconv_) {
+    __ibs_ = max<streamsize>(__n, sizeof(__extbuf_min_));
+    if (__s && __ibs_ > sizeof(__extbuf_min_)) {
+      __intbuf_  = __s;
+      __owns_ib_ = false;
+    } else {
+      __intbuf_  = new char_type[__ibs_];
+      __owns_ib_ = true;
     }
-    return this;
+  } else {
+    __ibs_     = 0;
+    __intbuf_  = nullptr;
+    __owns_ib_ = false;
+  }
+  return this;
 }
 
 template <class _CharT, class _Traits>
 typename basic_filebuf<_CharT, _Traits>::pos_type
-basic_filebuf<_CharT, _Traits>::seekoff(off_type __off, ios_base::seekdir __way,
-                                        ios_base::openmode)
-{
-    if (!__cv_)
-        __throw_bad_cast();
-
-    int __width = __cv_->encoding();
-    if (__file_ == nullptr || (__width <= 0 && __off != 0) || sync())
-        return pos_type(off_type(-1));
-    // __width > 0 || __off == 0
-    int __whence;
-    switch (__way)
-    {
-    case ios_base::beg:
-        __whence = SEEK_SET;
-        break;
-    case ios_base::cur:
-        __whence = SEEK_CUR;
-        break;
-    case ios_base::end:
-        __whence = SEEK_END;
-        break;
-    default:
-        return pos_type(off_type(-1));
-    }
-#if defined(_LIBCPP_HAS_NO_OFF_T_FUNCTIONS)
-    if (fseek(__file_, __width > 0 ? __width * __off : 0, __whence))
-        return pos_type(off_type(-1));
-    pos_type __r = ftell(__file_);
-#else
-    if (::fseeko(__file_, __width > 0 ? __width * __off : 0, __whence))
-        return pos_type(off_type(-1));
-    pos_type __r = ftello(__file_);
-#endif
-    __r.state(__st_);
-    return __r;
+basic_filebuf<_CharT, _Traits>::seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode) {
+  if (!__cv_)
+    __throw_bad_cast();
+
+  int __width = __cv_->encoding();
+  if (__file_ == nullptr || (__width <= 0 && __off != 0) || sync())
+    return pos_type(off_type(-1));
+  // __width > 0 || __off == 0
+  int __whence;
+  switch (__way) {
+  case ios_base::beg:
+    __whence = SEEK_SET;
+    break;
+  case ios_base::cur:
+    __whence = SEEK_CUR;
+    break;
+  case ios_base::end:
+    __whence = SEEK_END;
+    break;
+  default:
+    return pos_type(off_type(-1));
+  }
+#  if defined(_LIBCPP_HAS_NO_OFF_T_FUNCTIONS)
+  if (fseek(__file_, __width > 0 ? __width * __off : 0, __whence))
+    return pos_type(off_type(-1));
+  pos_type __r = ftell(__file_);
+#  else
+  if (::fseeko(__file_, __width > 0 ? __width * __off : 0, __whence))
+    return pos_type(off_type(-1));
+  pos_type __r = ftello(__file_);
+#  endif
+  __r.state(__st_);
+  return __r;
 }
 
 template <class _CharT, class _Traits>
 typename basic_filebuf<_CharT, _Traits>::pos_type
-basic_filebuf<_CharT, _Traits>::seekpos(pos_type __sp, ios_base::openmode)
-{
-    if (__file_ == nullptr || sync())
-        return pos_type(off_type(-1));
-#if defined(_LIBCPP_HAS_NO_OFF_T_FUNCTIONS)
-    if (fseek(__file_, __sp, SEEK_SET))
-        return pos_type(off_type(-1));
-#else
-    if (::fseeko(__file_, __sp, SEEK_SET))
-        return pos_type(off_type(-1));
-#endif
-    __st_ = __sp.state();
-    return __sp;
-}
-
-template <class _CharT, class _Traits>
-int
-basic_filebuf<_CharT, _Traits>::sync()
-{
-    if (__file_ == nullptr)
-        return 0;
-    if (!__cv_)
-        __throw_bad_cast();
+basic_filebuf<_CharT, _Traits>::seekpos(pos_type __sp, ios_base::openmode) {
+  if (__file_ == nullptr || sync())
+    return pos_type(off_type(-1));
+#  if defined(_LIBCPP_HAS_NO_OFF_T_FUNCTIONS)
+  if (fseek(__file_, __sp, SEEK_SET))
+    return pos_type(off_type(-1));
+#  else
+  if (::fseeko(__file_, __sp, SEEK_SET))
+    return pos_type(off_type(-1));
+#  endif
+  __st_ = __sp.state();
+  return __sp;
+}
+
+template <class _CharT, class _Traits>
+int basic_filebuf<_CharT, _Traits>::sync() {
+  if (__file_ == nullptr)
+    return 0;
+  if (!__cv_)
+    __throw_bad_cast();
 
-    if (__cm_ & ios_base::out)
-    {
-        if (this->pptr() != this->pbase())
-            if (overflow() == traits_type::eof())
-                return -1;
-        codecvt_base::result __r;
-        do
-        {
-            char* __extbe;
-            __r = __cv_->unshift(__st_, __extbuf_, __extbuf_ + __ebs_, __extbe);
-            size_t __nmemb = static_cast<size_t>(__extbe - __extbuf_);
-            if (fwrite(__extbuf_, 1, __nmemb, __file_) != __nmemb)
-                return -1;
-        } while (__r == codecvt_base::partial);
-        if (__r == codecvt_base::error)
-            return -1;
-        if (fflush(__file_))
-            return -1;
-    }
-    else if (__cm_ & ios_base::in)
-    {
-        off_type __c;
-        state_type __state = __st_last_;
-        bool __update_st = false;
-        if (__always_noconv_)
-            __c = this->egptr() - this->gptr();
-        else
-        {
-            int __width = __cv_->encoding();
-            __c = __extbufend_ - __extbufnext_;
-            if (__width > 0)
-                __c += __width * (this->egptr() - this->gptr());
-            else
-            {
-                if (this->gptr() != this->egptr())
-                {
-                    const int __off =  __cv_->length(__state, __extbuf_,
-                                                     __extbufnext_,
-                                                     this->gptr() - this->eback());
-                    __c += __extbufnext_ - __extbuf_ - __off;
-                    __update_st = true;
-                }
-            }
+  if (__cm_ & ios_base::out) {
+    if (this->pptr() != this->pbase())
+      if (overflow() == traits_type::eof())
+        return -1;
+    codecvt_base::result __r;
+    do {
+      char* __extbe;
+      __r            = __cv_->unshift(__st_, __extbuf_, __extbuf_ + __ebs_, __extbe);
+      size_t __nmemb = static_cast<size_t>(__extbe - __extbuf_);
+      if (fwrite(__extbuf_, 1, __nmemb, __file_) != __nmemb)
+        return -1;
+    } while (__r == codecvt_base::partial);
+    if (__r == codecvt_base::error)
+      return -1;
+    if (fflush(__file_))
+      return -1;
+  } else if (__cm_ & ios_base::in) {
+    off_type __c;
+    state_type __state = __st_last_;
+    bool __update_st   = false;
+    if (__always_noconv_)
+      __c = this->egptr() - this->gptr();
+    else {
+      int __width = __cv_->encoding();
+      __c         = __extbufend_ - __extbufnext_;
+      if (__width > 0)
+        __c += __width * (this->egptr() - this->gptr());
+      else {
+        if (this->gptr() != this->egptr()) {
+          const int __off = __cv_->length(__state, __extbuf_, __extbufnext_, this->gptr() - this->eback());
+          __c += __extbufnext_ - __extbuf_ - __off;
+          __update_st = true;
         }
-#if defined(_LIBCPP_HAS_NO_OFF_T_FUNCTIONS)
-        if (fseek(__file_, -__c, SEEK_CUR))
-            return -1;
-#else
-        if (::fseeko(__file_, -__c, SEEK_CUR))
-            return -1;
-#endif
-        if (__update_st)
-            __st_ = __state;
-        __extbufnext_ = __extbufend_ = __extbuf_;
-        this->setg(nullptr, nullptr, nullptr);
-        __cm_ = 0;
+      }
     }
-    return 0;
+#  if defined(_LIBCPP_HAS_NO_OFF_T_FUNCTIONS)
+    if (fseek(__file_, -__c, SEEK_CUR))
+      return -1;
+#  else
+    if (::fseeko(__file_, -__c, SEEK_CUR))
+      return -1;
+#  endif
+    if (__update_st)
+      __st_ = __state;
+    __extbufnext_ = __extbufend_ = __extbuf_;
+    this->setg(nullptr, nullptr, nullptr);
+    __cm_ = 0;
+  }
+  return 0;
 }
 
 template <class _CharT, class _Traits>
-void
-basic_filebuf<_CharT, _Traits>::imbue(const locale& __loc)
-{
-    sync();
-    __cv_ = &std::use_facet<codecvt<char_type, char, state_type> >(__loc);
-    bool __old_anc = __always_noconv_;
-    __always_noconv_ = __cv_->always_noconv();
-    if (__old_anc != __always_noconv_)
+void basic_filebuf<_CharT, _Traits>::imbue(const locale& __loc) {
+  sync();
+  __cv_            = &std::use_facet<codecvt<char_type, char, state_type> >(__loc);
+  bool __old_anc   = __always_noconv_;
+  __always_noconv_ = __cv_->always_noconv();
+  if (__old_anc != __always_noconv_) {
+    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_
     {
-        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_
-        {
-            if (__owns_eb_)
-                delete [] __extbuf_;
-            __owns_eb_ = __owns_ib_;
-            __ebs_ = __ibs_;
-            __extbuf_ = (char*)__intbuf_;
-            __ibs_ = 0;
-            __intbuf_ = nullptr;
-            __owns_ib_ = false;
-        }
-        else  // need to obtain an __intbuf_.
-        {     // If __extbuf_ is user-supplied, use it, else new __intbuf_
-            if (!__owns_eb_ && __extbuf_ != __extbuf_min_)
-            {
-                __ibs_ = __ebs_;
-                __intbuf_ = (char_type*)__extbuf_;
-                __owns_ib_ = false;
-                __extbuf_ = new char[__ebs_];
-                __owns_eb_ = true;
-            }
-            else
-            {
-                __ibs_ = __ebs_;
-                __intbuf_ = new char_type[__ibs_];
-                __owns_ib_ = true;
-            }
-        }
+      if (__owns_eb_)
+        delete[] __extbuf_;
+      __owns_eb_ = __owns_ib_;
+      __ebs_     = __ibs_;
+      __extbuf_  = (char*)__intbuf_;
+      __ibs_     = 0;
+      __intbuf_  = nullptr;
+      __owns_ib_ = false;
+    } else // need to obtain an __intbuf_.
+    {      // If __extbuf_ is user-supplied, use it, else new __intbuf_
+      if (!__owns_eb_ && __extbuf_ != __extbuf_min_) {
+        __ibs_     = __ebs_;
+        __intbuf_  = (char_type*)__extbuf_;
+        __owns_ib_ = false;
+        __extbuf_  = new char[__ebs_];
+        __owns_eb_ = true;
+      } else {
+        __ibs_     = __ebs_;
+        __intbuf_  = new char_type[__ibs_];
+        __owns_ib_ = true;
+      }
     }
+  }
 }
 
 template <class _CharT, class _Traits>
-bool
-basic_filebuf<_CharT, _Traits>::__read_mode()
-{
-    if (!(__cm_ & ios_base::in))
-    {
-        this->setp(nullptr, nullptr);
-        if (__always_noconv_)
-            this->setg((char_type*)__extbuf_,
-                       (char_type*)__extbuf_ + __ebs_,
-                       (char_type*)__extbuf_ + __ebs_);
-        else
-            this->setg(__intbuf_, __intbuf_ + __ibs_, __intbuf_ + __ibs_);
-        __cm_ = ios_base::in;
-        return true;
-    }
-    return false;
+bool basic_filebuf<_CharT, _Traits>::__read_mode() {
+  if (!(__cm_ & ios_base::in)) {
+    this->setp(nullptr, nullptr);
+    if (__always_noconv_)
+      this->setg((char_type*)__extbuf_, (char_type*)__extbuf_ + __ebs_, (char_type*)__extbuf_ + __ebs_);
+    else
+      this->setg(__intbuf_, __intbuf_ + __ibs_, __intbuf_ + __ibs_);
+    __cm_ = ios_base::in;
+    return true;
+  }
+  return false;
 }
 
 template <class _CharT, class _Traits>
-void
-basic_filebuf<_CharT, _Traits>::__write_mode()
-{
-    if (!(__cm_ & ios_base::out))
-    {
-        this->setg(nullptr, nullptr, nullptr);
-        if (__ebs_ > sizeof(__extbuf_min_))
-        {
-            if (__always_noconv_)
-                this->setp((char_type*)__extbuf_,
-                           (char_type*)__extbuf_ + (__ebs_ - 1));
-            else
-                this->setp(__intbuf_, __intbuf_ + (__ibs_ - 1));
-        }
-        else
-            this->setp(nullptr, nullptr);
-        __cm_ = ios_base::out;
-    }
+void basic_filebuf<_CharT, _Traits>::__write_mode() {
+  if (!(__cm_ & ios_base::out)) {
+    this->setg(nullptr, nullptr, nullptr);
+    if (__ebs_ > sizeof(__extbuf_min_)) {
+      if (__always_noconv_)
+        this->setp((char_type*)__extbuf_, (char_type*)__extbuf_ + (__ebs_ - 1));
+      else
+        this->setp(__intbuf_, __intbuf_ + (__ibs_ - 1));
+    } else
+      this->setp(nullptr, nullptr);
+    __cm_ = ios_base::out;
+  }
 }
 
 // basic_ifstream
 
 template <class _CharT, class _Traits>
-class _LIBCPP_TEMPLATE_VIS basic_ifstream
-    : public basic_istream<_CharT, _Traits>
-{
+class _LIBCPP_TEMPLATE_VIS basic_ifstream : public basic_istream<_CharT, _Traits> {
 public:
-    typedef _CharT                         char_type;
-    typedef _Traits                        traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-
-    _LIBCPP_INLINE_VISIBILITY
-    basic_ifstream();
-    _LIBCPP_INLINE_VISIBILITY
-    explicit basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in);
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
-    _LIBCPP_INLINE_VISIBILITY
-    explicit basic_ifstream(const wchar_t* __s, ios_base::openmode __mode = ios_base::in);
-#endif
-    _LIBCPP_INLINE_VISIBILITY
-    explicit basic_ifstream(const string& __s, ios_base::openmode __mode = ios_base::in);
-#if _LIBCPP_STD_VER >= 17
-    _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_INLINE_VISIBILITY
-    explicit basic_ifstream(const filesystem::path& __p, ios_base::openmode __mode = ios_base::in)
+  typedef _CharT char_type;
+  typedef _Traits traits_type;
+  typedef typename traits_type::int_type int_type;
+  typedef typename traits_type::pos_type pos_type;
+  typedef typename traits_type::off_type off_type;
+#  if _LIBCPP_STD_VER >= 26
+  using native_handle_type = typename basic_filebuf<_CharT, _Traits>::native_handle_type;
+#  endif
+
+  _LIBCPP_HIDE_FROM_ABI basic_ifstream();
+  _LIBCPP_HIDE_FROM_ABI explicit basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in);
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+  _LIBCPP_HIDE_FROM_ABI explicit basic_ifstream(const wchar_t* __s, ios_base::openmode __mode = ios_base::in);
+#  endif
+  _LIBCPP_HIDE_FROM_ABI explicit basic_ifstream(const string& __s, ios_base::openmode __mode = ios_base::in);
+#  if _LIBCPP_STD_VER >= 17
+  _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_HIDE_FROM_ABI explicit basic_ifstream(
+      const filesystem::path& __p, ios_base::openmode __mode = ios_base::in)
       : basic_ifstream(__p.c_str(), __mode) {}
-#endif // _LIBCPP_STD_VER >= 17
-    _LIBCPP_INLINE_VISIBILITY
-    basic_ifstream(basic_ifstream&& __rhs);
-    _LIBCPP_INLINE_VISIBILITY
-    basic_ifstream& operator=(basic_ifstream&& __rhs);
-    _LIBCPP_INLINE_VISIBILITY
-    void swap(basic_ifstream& __rhs);
-
-    _LIBCPP_INLINE_VISIBILITY
-    basic_filebuf<char_type, traits_type>* rdbuf() const;
-    _LIBCPP_INLINE_VISIBILITY
-    bool is_open() const;
-    void open(const char* __s, ios_base::openmode __mode = ios_base::in);
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
-    void open(const wchar_t* __s, ios_base::openmode __mode = ios_base::in);
-#endif
-    void open(const string& __s, ios_base::openmode __mode = ios_base::in);
-#if _LIBCPP_STD_VER >= 17
-    _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_INLINE_VISIBILITY
-    void open(const filesystem::path& __p,
-              ios_base::openmode __mode = ios_base::in) {
-      return open(__p.c_str(), __mode);
-    }
-#endif // _LIBCPP_STD_VER >= 17
+#  endif // _LIBCPP_STD_VER >= 17
+  _LIBCPP_HIDE_FROM_ABI basic_ifstream(basic_ifstream&& __rhs);
+  _LIBCPP_HIDE_FROM_ABI basic_ifstream& operator=(basic_ifstream&& __rhs);
+  _LIBCPP_HIDE_FROM_ABI void swap(basic_ifstream& __rhs);
+
+  _LIBCPP_HIDE_FROM_ABI basic_filebuf<char_type, traits_type>* rdbuf() const;
+#  if _LIBCPP_STD_VER >= 26
+  _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() const noexcept { return rdbuf()->native_handle(); }
+#  endif
+  _LIBCPP_HIDE_FROM_ABI bool is_open() const;
+  void open(const char* __s, ios_base::openmode __mode = ios_base::in);
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+  void open(const wchar_t* __s, ios_base::openmode __mode = ios_base::in);
+#  endif
+  void open(const string& __s, ios_base::openmode __mode = ios_base::in);
+#  if _LIBCPP_STD_VER >= 17
+  _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_HIDE_FROM_ABI void
+  open(const filesystem::path& __p, ios_base::openmode __mode = ios_base::in) {
+    return open(__p.c_str(), __mode);
+  }
+#  endif // _LIBCPP_STD_VER >= 17
 
-    _LIBCPP_INLINE_VISIBILITY
-    void __open(int __fd, ios_base::openmode __mode);
-    _LIBCPP_INLINE_VISIBILITY
-    void close();
+  _LIBCPP_HIDE_FROM_ABI void __open(int __fd, ios_base::openmode __mode);
+  _LIBCPP_HIDE_FROM_ABI void close();
 
 private:
-    basic_filebuf<char_type, traits_type> __sb_;
+  basic_filebuf<char_type, traits_type> __sb_;
 };
 
 template <class _CharT, class _Traits>
-inline
-basic_ifstream<_CharT, _Traits>::basic_ifstream()
-    : basic_istream<char_type, traits_type>(&__sb_)
-{
-}
+inline basic_ifstream<_CharT, _Traits>::basic_ifstream() : basic_istream<char_type, traits_type>(&__sb_) {}
 
 template <class _CharT, class _Traits>
-inline
-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) == nullptr)
-        this->setstate(ios_base::failbit);
+inline 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) == nullptr)
+    this->setstate(ios_base::failbit);
 }
 
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
 template <class _CharT, class _Traits>
-inline
-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) == nullptr)
-        this->setstate(ios_base::failbit);
+inline 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) == nullptr)
+    this->setstate(ios_base::failbit);
 }
-#endif
+#  endif
 
 template <class _CharT, class _Traits>
-inline
-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) == nullptr)
-        this->setstate(ios_base::failbit);
+inline 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) == nullptr)
+    this->setstate(ios_base::failbit);
 }
 
 template <class _CharT, class _Traits>
-inline
-basic_ifstream<_CharT, _Traits>::basic_ifstream(basic_ifstream&& __rhs)
-    : basic_istream<char_type, traits_type>(_VSTD::move(__rhs)),
-      __sb_(_VSTD::move(__rhs.__sb_))
-{
-    this->set_rdbuf(&__sb_);
+inline basic_ifstream<_CharT, _Traits>::basic_ifstream(basic_ifstream&& __rhs)
+    : basic_istream<char_type, traits_type>(std::move(__rhs)), __sb_(std::move(__rhs.__sb_)) {
+  this->set_rdbuf(&__sb_);
 }
 
 template <class _CharT, class _Traits>
-inline
-basic_ifstream<_CharT, _Traits>&
-basic_ifstream<_CharT, _Traits>::operator=(basic_ifstream&& __rhs)
-{
-    basic_istream<char_type, traits_type>::operator=(_VSTD::move(__rhs));
-    __sb_ = _VSTD::move(__rhs.__sb_);
-    return *this;
+inline basic_ifstream<_CharT, _Traits>& basic_ifstream<_CharT, _Traits>::operator=(basic_ifstream&& __rhs) {
+  basic_istream<char_type, traits_type>::operator=(std::move(__rhs));
+  __sb_ = std::move(__rhs.__sb_);
+  return *this;
 }
 
 template <class _CharT, class _Traits>
-inline
-void
-basic_ifstream<_CharT, _Traits>::swap(basic_ifstream& __rhs)
-{
-    basic_istream<char_type, traits_type>::swap(__rhs);
-    __sb_.swap(__rhs.__sb_);
+inline void basic_ifstream<_CharT, _Traits>::swap(basic_ifstream& __rhs) {
+  basic_istream<char_type, traits_type>::swap(__rhs);
+  __sb_.swap(__rhs.__sb_);
 }
 
 template <class _CharT, class _Traits>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-swap(basic_ifstream<_CharT, _Traits>& __x, basic_ifstream<_CharT, _Traits>& __y)
-{
-    __x.swap(__y);
+inline _LIBCPP_HIDE_FROM_ABI void swap(basic_ifstream<_CharT, _Traits>& __x, basic_ifstream<_CharT, _Traits>& __y) {
+  __x.swap(__y);
 }
 
 template <class _CharT, class _Traits>
-inline
-basic_filebuf<_CharT, _Traits>*
-basic_ifstream<_CharT, _Traits>::rdbuf() const
-{
-    return const_cast<basic_filebuf<char_type, traits_type>*>(&__sb_);
+inline basic_filebuf<_CharT, _Traits>* basic_ifstream<_CharT, _Traits>::rdbuf() const {
+  return const_cast<basic_filebuf<char_type, traits_type>*>(&__sb_);
 }
 
 template <class _CharT, class _Traits>
-inline
-bool
-basic_ifstream<_CharT, _Traits>::is_open() const
-{
-    return __sb_.is_open();
+inline bool basic_ifstream<_CharT, _Traits>::is_open() const {
+  return __sb_.is_open();
 }
 
 template <class _CharT, class _Traits>
-void
-basic_ifstream<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode)
-{
-    if (__sb_.open(__s, __mode | ios_base::in))
-        this->clear();
-    else
-        this->setstate(ios_base::failbit);
+void basic_ifstream<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode) {
+  if (__sb_.open(__s, __mode | ios_base::in))
+    this->clear();
+  else
+    this->setstate(ios_base::failbit);
 }
 
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
 template <class _CharT, class _Traits>
-void
-basic_ifstream<_CharT, _Traits>::open(const wchar_t* __s, ios_base::openmode __mode)
-{
-    if (__sb_.open(__s, __mode | ios_base::in))
-        this->clear();
-    else
-        this->setstate(ios_base::failbit);
+void basic_ifstream<_CharT, _Traits>::open(const wchar_t* __s, ios_base::openmode __mode) {
+  if (__sb_.open(__s, __mode | ios_base::in))
+    this->clear();
+  else
+    this->setstate(ios_base::failbit);
 }
-#endif
+#  endif
 
 template <class _CharT, class _Traits>
-void
-basic_ifstream<_CharT, _Traits>::open(const string& __s, ios_base::openmode __mode)
-{
-    if (__sb_.open(__s, __mode | ios_base::in))
-        this->clear();
-    else
-        this->setstate(ios_base::failbit);
+void basic_ifstream<_CharT, _Traits>::open(const string& __s, ios_base::openmode __mode) {
+  if (__sb_.open(__s, __mode | ios_base::in))
+    this->clear();
+  else
+    this->setstate(ios_base::failbit);
 }
 
 template <class _CharT, class _Traits>
-inline
-void basic_ifstream<_CharT, _Traits>::__open(int __fd,
-                                             ios_base::openmode __mode) {
+inline void basic_ifstream<_CharT, _Traits>::__open(int __fd, ios_base::openmode __mode) {
   if (__sb_.__open(__fd, __mode | ios_base::in))
     this->clear();
   else
@@ -1334,200 +1194,155 @@ void basic_ifstream<_CharT, _Traits>::__open(int __fd,
 }
 
 template <class _CharT, class _Traits>
-inline
-void
-basic_ifstream<_CharT, _Traits>::close()
-{
-    if (__sb_.close() == 0)
-        this->setstate(ios_base::failbit);
+inline void basic_ifstream<_CharT, _Traits>::close() {
+  if (__sb_.close() == 0)
+    this->setstate(ios_base::failbit);
 }
 
 // basic_ofstream
 
 template <class _CharT, class _Traits>
-class _LIBCPP_TEMPLATE_VIS basic_ofstream
-    : public basic_ostream<_CharT, _Traits>
-{
+class _LIBCPP_TEMPLATE_VIS basic_ofstream : public basic_ostream<_CharT, _Traits> {
 public:
-    typedef _CharT                         char_type;
-    typedef _Traits                        traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-
-    _LIBCPP_INLINE_VISIBILITY
-    basic_ofstream();
-    _LIBCPP_INLINE_VISIBILITY
-    explicit basic_ofstream(const char* __s, ios_base::openmode __mode = ios_base::out);
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
-    _LIBCPP_INLINE_VISIBILITY
-    explicit basic_ofstream(const wchar_t* __s, ios_base::openmode __mode = ios_base::out);
-#endif
-    _LIBCPP_INLINE_VISIBILITY
-    explicit basic_ofstream(const string& __s, ios_base::openmode __mode = ios_base::out);
-
-#if _LIBCPP_STD_VER >= 17
-    _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_INLINE_VISIBILITY
-    explicit basic_ofstream(const filesystem::path& __p, ios_base::openmode __mode = ios_base::out)
+  typedef _CharT char_type;
+  typedef _Traits traits_type;
+  typedef typename traits_type::int_type int_type;
+  typedef typename traits_type::pos_type pos_type;
+  typedef typename traits_type::off_type off_type;
+#  if _LIBCPP_STD_VER >= 26
+  using native_handle_type = typename basic_filebuf<_CharT, _Traits>::native_handle_type;
+#  endif
+
+  _LIBCPP_HIDE_FROM_ABI basic_ofstream();
+  _LIBCPP_HIDE_FROM_ABI explicit basic_ofstream(const char* __s, ios_base::openmode __mode = ios_base::out);
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+  _LIBCPP_HIDE_FROM_ABI explicit basic_ofstream(const wchar_t* __s, ios_base::openmode __mode = ios_base::out);
+#  endif
+  _LIBCPP_HIDE_FROM_ABI explicit basic_ofstream(const string& __s, ios_base::openmode __mode = ios_base::out);
+
+#  if _LIBCPP_STD_VER >= 17
+  _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_HIDE_FROM_ABI explicit basic_ofstream(
+      const filesystem::path& __p, ios_base::openmode __mode = ios_base::out)
       : basic_ofstream(__p.c_str(), __mode) {}
-#endif // _LIBCPP_STD_VER >= 17
-
-    _LIBCPP_INLINE_VISIBILITY
-    basic_ofstream(basic_ofstream&& __rhs);
-    _LIBCPP_INLINE_VISIBILITY
-    basic_ofstream& operator=(basic_ofstream&& __rhs);
-    _LIBCPP_INLINE_VISIBILITY
-    void swap(basic_ofstream& __rhs);
-
-    _LIBCPP_INLINE_VISIBILITY
-    basic_filebuf<char_type, traits_type>* rdbuf() const;
-    _LIBCPP_INLINE_VISIBILITY
-    bool is_open() const;
-    void open(const char* __s, ios_base::openmode __mode = ios_base::out);
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
-    void open(const wchar_t* __s, ios_base::openmode __mode = ios_base::out);
-#endif
-    void open(const string& __s, ios_base::openmode __mode = ios_base::out);
-
-#if _LIBCPP_STD_VER >= 17
-    _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_INLINE_VISIBILITY
-    void open(const filesystem::path& __p, ios_base::openmode __mode = ios_base::out)
-    { return open(__p.c_str(), __mode); }
-#endif // _LIBCPP_STD_VER >= 17
+#  endif // _LIBCPP_STD_VER >= 17
+
+  _LIBCPP_HIDE_FROM_ABI basic_ofstream(basic_ofstream&& __rhs);
+  _LIBCPP_HIDE_FROM_ABI basic_ofstream& operator=(basic_ofstream&& __rhs);
+  _LIBCPP_HIDE_FROM_ABI void swap(basic_ofstream& __rhs);
+
+  _LIBCPP_HIDE_FROM_ABI basic_filebuf<char_type, traits_type>* rdbuf() const;
+#  if _LIBCPP_STD_VER >= 26
+  _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() const noexcept { return rdbuf()->native_handle(); }
+#  endif
+  _LIBCPP_HIDE_FROM_ABI bool is_open() const;
+  void open(const char* __s, ios_base::openmode __mode = ios_base::out);
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+  void open(const wchar_t* __s, ios_base::openmode __mode = ios_base::out);
+#  endif
+  void open(const string& __s, ios_base::openmode __mode = ios_base::out);
+
+#  if _LIBCPP_STD_VER >= 17
+  _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_HIDE_FROM_ABI void
+  open(const filesystem::path& __p, ios_base::openmode __mode = ios_base::out) {
+    return open(__p.c_str(), __mode);
+  }
+#  endif // _LIBCPP_STD_VER >= 17
 
-    _LIBCPP_INLINE_VISIBILITY
-    void __open(int __fd, ios_base::openmode __mode);
-    _LIBCPP_INLINE_VISIBILITY
-    void close();
+  _LIBCPP_HIDE_FROM_ABI void __open(int __fd, ios_base::openmode __mode);
+  _LIBCPP_HIDE_FROM_ABI void close();
 
 private:
-    basic_filebuf<char_type, traits_type> __sb_;
+  basic_filebuf<char_type, traits_type> __sb_;
 };
 
 template <class _CharT, class _Traits>
-inline
-basic_ofstream<_CharT, _Traits>::basic_ofstream()
-    : basic_ostream<char_type, traits_type>(&__sb_)
-{
-}
+inline basic_ofstream<_CharT, _Traits>::basic_ofstream() : basic_ostream<char_type, traits_type>(&__sb_) {}
 
 template <class _CharT, class _Traits>
-inline
-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) == nullptr)
-        this->setstate(ios_base::failbit);
+inline 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) == nullptr)
+    this->setstate(ios_base::failbit);
 }
 
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
 template <class _CharT, class _Traits>
-inline
-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) == nullptr)
-        this->setstate(ios_base::failbit);
+inline 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) == nullptr)
+    this->setstate(ios_base::failbit);
 }
-#endif
+#  endif
 
 template <class _CharT, class _Traits>
-inline
-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) == nullptr)
-        this->setstate(ios_base::failbit);
+inline 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) == nullptr)
+    this->setstate(ios_base::failbit);
 }
 
 template <class _CharT, class _Traits>
-inline
-basic_ofstream<_CharT, _Traits>::basic_ofstream(basic_ofstream&& __rhs)
-    : basic_ostream<char_type, traits_type>(_VSTD::move(__rhs)),
-      __sb_(_VSTD::move(__rhs.__sb_))
-{
-    this->set_rdbuf(&__sb_);
+inline basic_ofstream<_CharT, _Traits>::basic_ofstream(basic_ofstream&& __rhs)
+    : basic_ostream<char_type, traits_type>(std::move(__rhs)), __sb_(std::move(__rhs.__sb_)) {
+  this->set_rdbuf(&__sb_);
 }
 
 template <class _CharT, class _Traits>
-inline
-basic_ofstream<_CharT, _Traits>&
-basic_ofstream<_CharT, _Traits>::operator=(basic_ofstream&& __rhs)
-{
-    basic_ostream<char_type, traits_type>::operator=(_VSTD::move(__rhs));
-    __sb_ = _VSTD::move(__rhs.__sb_);
-    return *this;
+inline basic_ofstream<_CharT, _Traits>& basic_ofstream<_CharT, _Traits>::operator=(basic_ofstream&& __rhs) {
+  basic_ostream<char_type, traits_type>::operator=(std::move(__rhs));
+  __sb_ = std::move(__rhs.__sb_);
+  return *this;
 }
 
 template <class _CharT, class _Traits>
-inline
-void
-basic_ofstream<_CharT, _Traits>::swap(basic_ofstream& __rhs)
-{
-    basic_ostream<char_type, traits_type>::swap(__rhs);
-    __sb_.swap(__rhs.__sb_);
+inline void basic_ofstream<_CharT, _Traits>::swap(basic_ofstream& __rhs) {
+  basic_ostream<char_type, traits_type>::swap(__rhs);
+  __sb_.swap(__rhs.__sb_);
 }
 
 template <class _CharT, class _Traits>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-swap(basic_ofstream<_CharT, _Traits>& __x, basic_ofstream<_CharT, _Traits>& __y)
-{
-    __x.swap(__y);
+inline _LIBCPP_HIDE_FROM_ABI void swap(basic_ofstream<_CharT, _Traits>& __x, basic_ofstream<_CharT, _Traits>& __y) {
+  __x.swap(__y);
 }
 
 template <class _CharT, class _Traits>
-inline
-basic_filebuf<_CharT, _Traits>*
-basic_ofstream<_CharT, _Traits>::rdbuf() const
-{
-    return const_cast<basic_filebuf<char_type, traits_type>*>(&__sb_);
+inline basic_filebuf<_CharT, _Traits>* basic_ofstream<_CharT, _Traits>::rdbuf() const {
+  return const_cast<basic_filebuf<char_type, traits_type>*>(&__sb_);
 }
 
 template <class _CharT, class _Traits>
-inline
-bool
-basic_ofstream<_CharT, _Traits>::is_open() const
-{
-    return __sb_.is_open();
+inline bool basic_ofstream<_CharT, _Traits>::is_open() const {
+  return __sb_.is_open();
 }
 
 template <class _CharT, class _Traits>
-void
-basic_ofstream<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode)
-{
-    if (__sb_.open(__s, __mode | ios_base::out))
-        this->clear();
-    else
-        this->setstate(ios_base::failbit);
+void basic_ofstream<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode) {
+  if (__sb_.open(__s, __mode | ios_base::out))
+    this->clear();
+  else
+    this->setstate(ios_base::failbit);
 }
 
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
 template <class _CharT, class _Traits>
-void
-basic_ofstream<_CharT, _Traits>::open(const wchar_t* __s, ios_base::openmode __mode)
-{
-    if (__sb_.open(__s, __mode | ios_base::out))
-        this->clear();
-    else
-        this->setstate(ios_base::failbit);
+void basic_ofstream<_CharT, _Traits>::open(const wchar_t* __s, ios_base::openmode __mode) {
+  if (__sb_.open(__s, __mode | ios_base::out))
+    this->clear();
+  else
+    this->setstate(ios_base::failbit);
 }
-#endif
+#  endif
 
 template <class _CharT, class _Traits>
-void
-basic_ofstream<_CharT, _Traits>::open(const string& __s, ios_base::openmode __mode)
-{
-    if (__sb_.open(__s, __mode | ios_base::out))
-        this->clear();
-    else
-        this->setstate(ios_base::failbit);
+void basic_ofstream<_CharT, _Traits>::open(const string& __s, ios_base::openmode __mode) {
+  if (__sb_.open(__s, __mode | ios_base::out))
+    this->clear();
+  else
+    this->setstate(ios_base::failbit);
 }
 
 template <class _CharT, class _Traits>
-inline
-void basic_ofstream<_CharT, _Traits>::__open(int __fd,
-                                             ios_base::openmode __mode) {
+inline void basic_ofstream<_CharT, _Traits>::__open(int __fd, ios_base::openmode __mode) {
   if (__sb_.__open(__fd, __mode | ios_base::out))
     this->clear();
   else
@@ -1535,210 +1350,168 @@ void basic_ofstream<_CharT, _Traits>::__open(int __fd,
 }
 
 template <class _CharT, class _Traits>
-inline
-void
-basic_ofstream<_CharT, _Traits>::close()
-{
-    if (__sb_.close() == nullptr)
-        this->setstate(ios_base::failbit);
+inline void basic_ofstream<_CharT, _Traits>::close() {
+  if (__sb_.close() == nullptr)
+    this->setstate(ios_base::failbit);
 }
 
 // basic_fstream
 
 template <class _CharT, class _Traits>
-class _LIBCPP_TEMPLATE_VIS basic_fstream
-    : public basic_iostream<_CharT, _Traits>
-{
+class _LIBCPP_TEMPLATE_VIS basic_fstream : public basic_iostream<_CharT, _Traits> {
 public:
-    typedef _CharT                         char_type;
-    typedef _Traits                        traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-
-    _LIBCPP_INLINE_VISIBILITY
-    basic_fstream();
-    _LIBCPP_INLINE_VISIBILITY
-    explicit basic_fstream(const char* __s, ios_base::openmode __mode = ios_base::in | ios_base::out);
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
-    _LIBCPP_INLINE_VISIBILITY
-    explicit basic_fstream(const wchar_t* __s, ios_base::openmode __mode = ios_base::in | ios_base::out);
-#endif
-    _LIBCPP_INLINE_VISIBILITY
-    explicit basic_fstream(const string& __s, ios_base::openmode __mode = ios_base::in | ios_base::out);
-
-#if _LIBCPP_STD_VER >= 17
-    _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_INLINE_VISIBILITY
-    explicit basic_fstream(const filesystem::path& __p, ios_base::openmode __mode = ios_base::in | ios_base::out)
+  typedef _CharT char_type;
+  typedef _Traits traits_type;
+  typedef typename traits_type::int_type int_type;
+  typedef typename traits_type::pos_type pos_type;
+  typedef typename traits_type::off_type off_type;
+#  if _LIBCPP_STD_VER >= 26
+  using native_handle_type = typename basic_filebuf<_CharT, _Traits>::native_handle_type;
+#  endif
+
+  _LIBCPP_HIDE_FROM_ABI basic_fstream();
+  _LIBCPP_HIDE_FROM_ABI explicit basic_fstream(const char* __s,
+                                               ios_base::openmode __mode = ios_base::in | ios_base::out);
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+  _LIBCPP_HIDE_FROM_ABI explicit basic_fstream(const wchar_t* __s,
+                                               ios_base::openmode __mode = ios_base::in | ios_base::out);
+#  endif
+  _LIBCPP_HIDE_FROM_ABI explicit basic_fstream(const string& __s,
+                                               ios_base::openmode __mode = ios_base::in | ios_base::out);
+
+#  if _LIBCPP_STD_VER >= 17
+  _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_HIDE_FROM_ABI explicit basic_fstream(
+      const filesystem::path& __p, ios_base::openmode __mode = ios_base::in | ios_base::out)
       : basic_fstream(__p.c_str(), __mode) {}
-#endif // _LIBCPP_STD_VER >= 17
+#  endif // _LIBCPP_STD_VER >= 17
 
-    _LIBCPP_INLINE_VISIBILITY
-    basic_fstream(basic_fstream&& __rhs);
+  _LIBCPP_HIDE_FROM_ABI basic_fstream(basic_fstream&& __rhs);
 
-    _LIBCPP_INLINE_VISIBILITY
-    basic_fstream& operator=(basic_fstream&& __rhs);
+  _LIBCPP_HIDE_FROM_ABI basic_fstream& operator=(basic_fstream&& __rhs);
 
-    _LIBCPP_INLINE_VISIBILITY
-    void swap(basic_fstream& __rhs);
+  _LIBCPP_HIDE_FROM_ABI void swap(basic_fstream& __rhs);
 
-    _LIBCPP_INLINE_VISIBILITY
-    basic_filebuf<char_type, traits_type>* rdbuf() const;
-    _LIBCPP_INLINE_VISIBILITY
-    bool is_open() const;
-    _LIBCPP_HIDE_FROM_ABI void open(const char* __s, ios_base::openmode __mode = ios_base::in | ios_base::out);
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
-    void open(const wchar_t* __s, ios_base::openmode __mode = ios_base::in | ios_base::out);
-#endif
-    _LIBCPP_HIDE_FROM_ABI void open(const string& __s, ios_base::openmode __mode = ios_base::in | ios_base::out);
+  _LIBCPP_HIDE_FROM_ABI basic_filebuf<char_type, traits_type>* rdbuf() const;
+#  if _LIBCPP_STD_VER >= 26
+  _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() const noexcept { return rdbuf()->native_handle(); }
+#  endif
+  _LIBCPP_HIDE_FROM_ABI bool is_open() const;
+  _LIBCPP_HIDE_FROM_ABI void open(const char* __s, ios_base::openmode __mode = ios_base::in | ios_base::out);
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+  void open(const wchar_t* __s, ios_base::openmode __mode = ios_base::in | ios_base::out);
+#  endif
+  _LIBCPP_HIDE_FROM_ABI void open(const string& __s, ios_base::openmode __mode = ios_base::in | ios_base::out);
 
-#if _LIBCPP_STD_VER >= 17
-    _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_INLINE_VISIBILITY
-    void open(const filesystem::path& __p, ios_base::openmode __mode = ios_base::in|ios_base::out)
-    { return open(__p.c_str(), __mode); }
-#endif // _LIBCPP_STD_VER >= 17
+#  if _LIBCPP_STD_VER >= 17
+  _LIBCPP_AVAILABILITY_FILESYSTEM_LIBRARY _LIBCPP_HIDE_FROM_ABI void
+  open(const filesystem::path& __p, ios_base::openmode __mode = ios_base::in | ios_base::out) {
+    return open(__p.c_str(), __mode);
+  }
+#  endif // _LIBCPP_STD_VER >= 17
 
-    _LIBCPP_INLINE_VISIBILITY
-    void close();
+  _LIBCPP_HIDE_FROM_ABI void close();
 
 private:
-    basic_filebuf<char_type, traits_type> __sb_;
+  basic_filebuf<char_type, traits_type> __sb_;
 };
 
 template <class _CharT, class _Traits>
-inline
-basic_fstream<_CharT, _Traits>::basic_fstream()
-    : basic_iostream<char_type, traits_type>(&__sb_)
-{
-}
+inline basic_fstream<_CharT, _Traits>::basic_fstream() : basic_iostream<char_type, traits_type>(&__sb_) {}
 
 template <class _CharT, class _Traits>
-inline
-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) == nullptr)
-        this->setstate(ios_base::failbit);
+inline 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) == nullptr)
+    this->setstate(ios_base::failbit);
 }
 
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
 template <class _CharT, class _Traits>
-inline
-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) == nullptr)
-        this->setstate(ios_base::failbit);
+inline 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) == nullptr)
+    this->setstate(ios_base::failbit);
 }
-#endif
+#  endif
 
 template <class _CharT, class _Traits>
-inline
-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) == nullptr)
-        this->setstate(ios_base::failbit);
+inline 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) == nullptr)
+    this->setstate(ios_base::failbit);
 }
 
 template <class _CharT, class _Traits>
-inline
-basic_fstream<_CharT, _Traits>::basic_fstream(basic_fstream&& __rhs)
-    : basic_iostream<char_type, traits_type>(_VSTD::move(__rhs)),
-      __sb_(_VSTD::move(__rhs.__sb_))
-{
-    this->set_rdbuf(&__sb_);
+inline basic_fstream<_CharT, _Traits>::basic_fstream(basic_fstream&& __rhs)
+    : basic_iostream<char_type, traits_type>(std::move(__rhs)), __sb_(std::move(__rhs.__sb_)) {
+  this->set_rdbuf(&__sb_);
 }
 
 template <class _CharT, class _Traits>
-inline
-basic_fstream<_CharT, _Traits>&
-basic_fstream<_CharT, _Traits>::operator=(basic_fstream&& __rhs)
-{
-    basic_iostream<char_type, traits_type>::operator=(_VSTD::move(__rhs));
-    __sb_ = _VSTD::move(__rhs.__sb_);
-    return *this;
+inline basic_fstream<_CharT, _Traits>& basic_fstream<_CharT, _Traits>::operator=(basic_fstream&& __rhs) {
+  basic_iostream<char_type, traits_type>::operator=(std::move(__rhs));
+  __sb_ = std::move(__rhs.__sb_);
+  return *this;
 }
 
 template <class _CharT, class _Traits>
-inline
-void
-basic_fstream<_CharT, _Traits>::swap(basic_fstream& __rhs)
-{
-    basic_iostream<char_type, traits_type>::swap(__rhs);
-    __sb_.swap(__rhs.__sb_);
+inline void basic_fstream<_CharT, _Traits>::swap(basic_fstream& __rhs) {
+  basic_iostream<char_type, traits_type>::swap(__rhs);
+  __sb_.swap(__rhs.__sb_);
 }
 
 template <class _CharT, class _Traits>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-swap(basic_fstream<_CharT, _Traits>& __x, basic_fstream<_CharT, _Traits>& __y)
-{
-    __x.swap(__y);
+inline _LIBCPP_HIDE_FROM_ABI void swap(basic_fstream<_CharT, _Traits>& __x, basic_fstream<_CharT, _Traits>& __y) {
+  __x.swap(__y);
 }
 
 template <class _CharT, class _Traits>
-inline
-basic_filebuf<_CharT, _Traits>*
-basic_fstream<_CharT, _Traits>::rdbuf() const
-{
-    return const_cast<basic_filebuf<char_type, traits_type>*>(&__sb_);
+inline basic_filebuf<_CharT, _Traits>* basic_fstream<_CharT, _Traits>::rdbuf() const {
+  return const_cast<basic_filebuf<char_type, traits_type>*>(&__sb_);
 }
 
 template <class _CharT, class _Traits>
-inline
-bool
-basic_fstream<_CharT, _Traits>::is_open() const
-{
-    return __sb_.is_open();
+inline bool basic_fstream<_CharT, _Traits>::is_open() const {
+  return __sb_.is_open();
 }
 
 template <class _CharT, class _Traits>
-void
-basic_fstream<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode)
-{
-    if (__sb_.open(__s, __mode))
-        this->clear();
-    else
-        this->setstate(ios_base::failbit);
+void basic_fstream<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode) {
+  if (__sb_.open(__s, __mode))
+    this->clear();
+  else
+    this->setstate(ios_base::failbit);
 }
 
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
 template <class _CharT, class _Traits>
-void
-basic_fstream<_CharT, _Traits>::open(const wchar_t* __s, ios_base::openmode __mode)
-{
-    if (__sb_.open(__s, __mode))
-        this->clear();
-    else
-        this->setstate(ios_base::failbit);
+void basic_fstream<_CharT, _Traits>::open(const wchar_t* __s, ios_base::openmode __mode) {
+  if (__sb_.open(__s, __mode))
+    this->clear();
+  else
+    this->setstate(ios_base::failbit);
 }
-#endif
+#  endif
 
 template <class _CharT, class _Traits>
-void
-basic_fstream<_CharT, _Traits>::open(const string& __s, ios_base::openmode __mode)
-{
-    if (__sb_.open(__s, __mode))
-        this->clear();
-    else
-        this->setstate(ios_base::failbit);
+void basic_fstream<_CharT, _Traits>::open(const string& __s, ios_base::openmode __mode) {
+  if (__sb_.open(__s, __mode))
+    this->clear();
+  else
+    this->setstate(ios_base::failbit);
 }
 
 template <class _CharT, class _Traits>
-inline
-void
-basic_fstream<_CharT, _Traits>::close()
-{
-    if (__sb_.close() == nullptr)
-        this->setstate(ios_base::failbit);
+inline void basic_fstream<_CharT, _Traits>::close() {
+  if (__sb_.close() == nullptr)
+    this->setstate(ios_base::failbit);
 }
 
-#if defined(_LIBCPP_ABI_ENABLE_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1)
+#  if _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ifstream<char>;
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ofstream<char>;
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_filebuf<char>;
-#endif
+#  endif
 
 _LIBCPP_END_NAMESPACE_STD
 
@@ -1752,6 +1525,7 @@ _LIBCPP_POP_MACROS
 #  include <cstdlib>
 #  include <iosfwd>
 #  include <limits>
+#  include <mutex>
 #  include <new>
 #  include <stdexcept>
 #  include <type_traits>