Revert "[libc++][streams] P1759R6: Native handles and file streams (#76632)"

This reverts commit 255f95a, which
contains a breaking libcxx test on Windows when using C++26

Author: zeroomega

libcxx/docs/FeatureTestMacroTable.rst

@@ -418,7 +418,7 @@ Status
     --------------------------------------------------- -----------------
     ``__cpp_lib_freestanding_variant``                  *unimplemented*
     --------------------------------------------------- -----------------
-    ``__cpp_lib_fstream_native_handle``                 ``202306L``
+    ``__cpp_lib_fstream_native_handle``                 *unimplemented*
     --------------------------------------------------- -----------------
     ``__cpp_lib_function_ref``                          *unimplemented*
     --------------------------------------------------- -----------------

libcxx/docs/ReleaseNotes/18.rst

@@ -59,7 +59,6 @@ Implemented Papers
 - P2909R4 - Fix formatting of code units as integers (Dude, where’s my ``char``?)
 - P2821R5 - span.at()
 - P0521R0 - Proposed Resolution for CA 14 (shared_ptr use_count/unique)
-- P1759R6 - Native handles and file streams
 
 
 Improvements and New Features

libcxx/docs/Status/Cxx2cPapers.csv

@@ -19,7 +19,7 @@
 "`P2757R3 <https://wg21.link/P2757R3>`__","LWG","Type-checking format args","Varna June 2023","","","|format|"
 "`P2637R3 <https://wg21.link/P2637R3>`__","LWG","Member ``visit``","Varna June 2023","","","|format|"
 "`P2641R4 <https://wg21.link/P2641R4>`__","CWG, LWG","Checking if a ``union`` alternative is active","Varna June 2023","","",""
-"`P1759R6 <https://wg21.link/P1759R6>`__","LWG","Native handles and file streams","Varna June 2023","|Complete|","18.0",""
+"`P1759R6 <https://wg21.link/P1759R6>`__","LWG","Native handles and file streams","Varna June 2023","","",""
 "`P2697R1 <https://wg21.link/P2697R1>`__","LWG","Interfacing ``bitset`` with ``string_view``","Varna June 2023","|Complete|","18.0",""
 "`P1383R2 <https://wg21.link/P1383R2>`__","LWG","More ``constexpr`` for ``<cmath>`` and ``<complex>``","Varna June 2023","","",""
 "`P2734R0 <https://wg21.link/P2734R0>`__","LWG","Adding the new SI prefixes","Varna June 2023","|Complete|","17.0",""

libcxx/include/fstream

@@ -73,7 +73,6 @@ 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);
@@ -86,7 +85,6 @@ 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);
@@ -112,7 +110,6 @@ 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);
@@ -125,8 +122,6 @@ 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);
@@ -153,7 +148,6 @@ 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);
@@ -166,7 +160,6 @@ 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);
@@ -217,10 +210,6 @@ _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);
-#  endif
-
 template <class _CharT, class _Traits>
 class _LIBCPP_TEMPLATE_VIS basic_filebuf : public basic_streambuf<_CharT, _Traits> {
 public:
@@ -230,15 +219,6 @@ public:
   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();
@@ -265,18 +245,6 @@ public:
 #  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_HIDE_FROM_ABI inline static const char* __make_mdstring(ios_base::openmode __mode) _NOEXCEPT;
 
@@ -1056,9 +1024,6 @@ 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;
-#  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);
@@ -1076,9 +1041,6 @@ public:
   _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
@@ -1209,9 +1171,6 @@ 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;
-#  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);
@@ -1231,9 +1190,6 @@ public:
   _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
@@ -1365,9 +1321,6 @@ 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;
-#  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,
@@ -1392,9 +1345,6 @@ public:
   _LIBCPP_HIDE_FROM_ABI void swap(basic_fstream& __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;
   _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

libcxx/include/version

@@ -496,7 +496,7 @@ __cpp_lib_within_lifetime                               202306L <type_traits>
 // # define __cpp_lib_freestanding_optional                202311L
 // # define __cpp_lib_freestanding_string_view             202311L
 // # define __cpp_lib_freestanding_variant                 202311L
-# define __cpp_lib_fstream_native_handle                202306L
+// # define __cpp_lib_fstream_native_handle                202306L
 // # define __cpp_lib_function_ref                         202306L
 // # define __cpp_lib_hazard_pointer                       202306L
 // # define __cpp_lib_linalg                               202311L

libcxx/src/CMakeLists.txt

@@ -84,7 +84,6 @@ endif()
 
 if (LIBCXX_ENABLE_LOCALIZATION)
   list(APPEND LIBCXX_SOURCES
-    fstream.cpp
     include/sso_allocator.h
     ios.cpp
     ios.instantiations.cpp

libcxx/src/fstream.cpp

@@ -23,7 +23,6 @@
 #include <type_traits>
 
 #include "test_macros.h"
-#include "../native_handle_test_helpers.h"
 
 int main(int, char**)
 {
@@ -33,12 +32,6 @@ int main(int, char**)
     static_assert((std::is_same<std::basic_filebuf<char>::int_type, std::char_traits<char>::int_type>::value), "");
     static_assert((std::is_same<std::basic_filebuf<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_filebuf<char>::off_type, std::char_traits<char>::off_type>::value), "");
-#if TEST_STD_VER >= 26
-    test_native_handle_type< std::basic_filebuf<char>>();
-#  ifndef TEST_HAS_NO_WIDE_CHARACTERS
-    test_native_handle_type< std::basic_filebuf<wchar_t>>();
-#  endif
-#endif
 
-    return 0;
+  return 0;
 }