[libc++] Make bsd_locale_fallbacks.h modular and move it into __locale/locale_base_api/

[philnik]

Summary

This is a first step towards granularizing <locale>.

[philnik]

Try to fix CI

[philnik]

Try to fix CI

[ldionne]

libcxx/include/CMakeLists.txt

217

Granularization patches are usually pretty mechanical because the organization of our headers already makes sense. However, the organization in <locale> makes little sense (at least to me). There's clearly some design trying to emerge, but it seems to have grown in weird ways with time. So I think it is worth designing how we want the organization to look like. I suggest:

__locale_dir/
    locale_base_api/
        bsd_locale_defaults.h   // 
        bsd_locale_fallbacks.h  // These headers are meant to be included by the per-platform
        locale_guard.h          // shims to provide the BSD-like API that we expect
 
        android.h
        solaris.h
        [...]
        freebsd.h
    locale_base_api.h           // This header would contain an #if-else chain that includes the
                                // appropriate shims for the current platform. It would also document 
                                // what base API a new platform has to support for libc++ to support 
                                // <locale>, which is kind of missing right now.
    scan_keyword.h
    [...]

Then, in <locale> we would include <__locale_dir/shims.h> and we would be guaranteed to have a BSD-like API available.

This patch doesn't have to go all the way, but once we agree on the end organization, I would move stuff around in a way that's consistent with where we want to end up.

[philnik]

Address comments

[philnik]

Try to fix CI

[philnik]

Try to fix CI

[philnik]

Next try

[philnik]

Next try

[philnik]

Fix lint_modulemap.sh.py

[philnik]

Try to fix CI

[philnik]

Next try

[philnik]

Try to fix CI

[philnik]

Try to fix CI

[philnik]

Try to fix CI

[philnik]

Another try

[philnik]

Try to fix CI

[philnik]

Try to fix CI

[philnik]

Try to fix CI

[philnik]

Try to fix CI

[philnik]

Next try

[ldionne]

libcxx/include/__locale_dir/locale_base_api/bsd_locale_defaults.h

14–15

This doesn't seem right anymore. Please check the other ones as well.

libcxx/utils/generate_iwyu_mapping.py

33

I thought __tuple_dir had been renamed to __tuple already, maybe you need to rebase?

[philnik]

Address comments

libcxx/include/CMakeLists.txt

set(files
   __atomic/memory_order.h
   __availability
   __bit/bit_cast.h
   __bit/bit_ceil.h
   __bit/bit_floor.h
   __bit/bit_log2.h
   __bit/bit_width.h
   __bit/blsr.h
   __bit/byteswap.h
   __bit/countl.h
   __bit/countr.h
   __bit/endian.h
   __bit/has_single_bit.h
   __bit/popcount.h
   __bit/rotate.h
   __bit_reference
-  __bsd_locale_defaults.h
-  __bsd_locale_fallbacks.h
   __charconv/chars_format.h
   __charconv/from_chars_integral.h
   __charconv/from_chars_result.h
   __charconv/tables.h
   __charconv/to_chars.h
   __charconv/to_chars_base_10.h
   __charconv/to_chars_floating_point.h
   __charconv/to_chars_integral.h
set(files
   __iterator/reverse_access.h
   __iterator/reverse_iterator.h
   __iterator/segmented_iterator.h
   __iterator/size.h
   __iterator/sortable.h
   __iterator/unreachable_sentinel.h
   __iterator/wrap_iter.h
   __locale
+  __locale_dir/locale_base_api/bsd_locale_defaults.h
+  __locale_dir/locale_base_api/bsd_locale_fallbacks.h
+  __locale_dir/locale_base_api/locale_guard.h
   __mbstate_t.h
   __memory/addressof.h
   __memory/align.h
   __memory/aligned_alloc.h
   __memory/allocate_at_least.h
   __memory/allocation_guard.h
   __memory/allocator.h
   __memory/allocator_arg_t.h

libcxx/include/__locale

 // -*- C++ -*-
 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef _LIBCPP___LOCALE
 #define _LIBCPP___LOCALE
 
 #include <__availability>
 #include <__config>
 #include <cctype>
+#include <clocale>
 #include <cstdint>
 #include <cstdlib>
-#include <locale.h>
 #include <mutex>
 #include <string>
 
 // Some platforms require more includes than others. Keep the includes on all plaforms for now.
 #include <cstddef>
 #include <cstring>
 
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+#  include <cwchar>
+#endif
+
 #if defined(_LIBCPP_MSVCRT_LIKE)
 # include <__support/win32/locale_win32.h>
 #elif defined(_AIX) || defined(__MVS__)
 # include <__support/ibm/xlocale.h>
 #elif defined(__ANDROID__)
 # include <__support/android/locale_bionic.h>
 #elif defined(__sun__)
 # include <__support/solaris/xlocale.h>

 #endif
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if !defined(_LIBCPP_LOCALE__L_EXTENSIONS)
-struct __libcpp_locale_guard {
-  _LIBCPP_INLINE_VISIBILITY
-  __libcpp_locale_guard(locale_t& __loc) : __old_loc_(uselocale(__loc)) {}
-
-  _LIBCPP_INLINE_VISIBILITY
-  ~__libcpp_locale_guard() {
-    if (__old_loc_)
-      uselocale(__old_loc_);
-  }
-
-  locale_t __old_loc_;
-private:
-  __libcpp_locale_guard(__libcpp_locale_guard const&);
-  __libcpp_locale_guard& operator=(__libcpp_locale_guard const&);
-};
-#elif defined(_LIBCPP_MSVCRT_LIKE)
-struct __libcpp_locale_guard {
-    __libcpp_locale_guard(locale_t __l) :
-        __status(_configthreadlocale(_ENABLE_PER_THREAD_LOCALE)) {
-      // Setting the locale can be expensive even when the locale given is
-      // already the current locale, so do an explicit check to see if the
-      // current locale is already the one we want.
-      const char* __lc = __setlocale(nullptr);
-      // If every category is the same, the locale string will simply be the
-      // locale name, otherwise it will be a semicolon-separated string listing
-      // each category.  In the second case, we know at least one category won't
-      // be what we want, so we only have to check the first case.
-      if (_VSTD::strcmp(__l.__get_locale(), __lc) != 0) {
-        __locale_all = _strdup(__lc);
-        if (__locale_all == nullptr)
-          __throw_bad_alloc();
-        __setlocale(__l.__get_locale());
-      }
-    }
-    ~__libcpp_locale_guard() {
-      // The CRT documentation doesn't explicitly say, but setlocale() does the
-      // right thing when given a semicolon-separated list of locale settings
-      // for the different categories in the same format as returned by
-      // setlocale(LC_ALL, nullptr).
-      if (__locale_all != nullptr) {
-        __setlocale(__locale_all);
-        free(__locale_all);
-      }
-      _configthreadlocale(__status);
-    }
-    static const char* __setlocale(const char* __locale) {
-      const char* __new_locale = setlocale(LC_ALL, __locale);
-      if (__new_locale == nullptr)
-        __throw_bad_alloc();
-      return __new_locale;
-    }
-    int __status;
-    char* __locale_all = nullptr;
-};
-#endif
-
 class _LIBCPP_TYPE_VIS locale;
 
 template <class _Facet>
 _LIBCPP_INLINE_VISIBILITY
 bool
 has_facet(const locale&) _NOEXCEPT;
 
 template <class _Facet>

libcxx/include/__locale_dir/locale_base_api/bsd_locale_defaults.h

 // -*- C++ -*-
 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 // The BSDs have lots of *_l functions.  We don't want to define those symbols
 // on other platforms though, for fear of conflicts with user code.  So here,
 // we will define the mapping from an internal macro to the real BSD symbol.
 //===----------------------------------------------------------------------===//
 
-#ifndef _LIBCPP___BSD_LOCALE_DEFAULTS_H
-#define _LIBCPP___BSD_LOCALE_DEFAULTS_H
+#ifndef _LIBCPP___LOCALE_LOCALE_BASE_API_BSD_LOCALE_DEFAULTS_H
+#define _LIBCPP___LOCALE_LOCALE_BASE_API_BSD_LOCALE_DEFAULTS_H
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 #define __libcpp_mb_cur_max_l(loc)                          MB_CUR_MAX_L(loc)
 #define __libcpp_btowc_l(ch, loc)                           btowc_l(ch, loc)
 #define __libcpp_wctob_l(wch, loc)                          wctob_l(wch, loc)
 #define __libcpp_wcsnrtombs_l(dst, src, nwc, len, ps, loc)  wcsnrtombs_l(dst, src, nwc, len, ps, loc)
 #define __libcpp_wcrtomb_l(src, wc, ps, loc)                wcrtomb_l(src, wc, ps, loc)
 #define __libcpp_mbsnrtowcs_l(dst, src, nms, len, ps, loc)  mbsnrtowcs_l(dst, src, nms, len, ps, loc)
 #define __libcpp_mbrtowc_l(pwc, s, n, ps, l)                mbrtowc_l(pwc, s, n, ps, l)
 #define __libcpp_mbtowc_l(pwc, pmb, max, l)                 mbtowc_l(pwc, pmb, max, l)
 #define __libcpp_mbrlen_l(s, n, ps, l)                      mbrlen_l(s, n, ps, l)
 #define __libcpp_localeconv_l(l)                            localeconv_l(l)
 #define __libcpp_mbsrtowcs_l(dest, src, len, ps, l)         mbsrtowcs_l(dest, src, len, ps, l)
 #define __libcpp_snprintf_l(...)                            snprintf_l(__VA_ARGS__)
 #define __libcpp_asprintf_l(...)                            asprintf_l(__VA_ARGS__)
 #define __libcpp_sscanf_l(...)                              sscanf_l(__VA_ARGS__)
 
-#endif // _LIBCPP___BSD_LOCALE_DEFAULTS_H
+#endif // _LIBCPP___LOCALE_LOCALE_BASE_API_BSD_LOCALE_DEFAULTS_H

libcxx/include/__locale_dir/locale_base_api/bsd_locale_fallbacks.h

 // -*- C++ -*-
 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 // The BSDs have lots of *_l functions.  This file provides reimplementations
 // of those functions for non-BSD platforms.
 //===----------------------------------------------------------------------===//
 
-#ifndef _LIBCPP___BSD_LOCALE_FALLBACKS_H
-#define _LIBCPP___BSD_LOCALE_FALLBACKS_H
+#ifndef _LIBCPP___LOCALE_LOCALE_BASE_API_BSD_LOCALE_FALLBACKS_H
+#define _LIBCPP___LOCALE_LOCALE_BASE_API_BSD_LOCALE_FALLBACKS_H
 
+#include <__locale_dir/locale_base_api/locale_guard.h>
+#include <cstdio>
 #include <stdarg.h>
 #include <stdlib.h>
 
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+#  include <cwchar>
+#endif
+
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 inline _LIBCPP_INLINE_VISIBILITY
 decltype(MB_CUR_MAX) __libcpp_mb_cur_max_l(locale_t __l)
int __libcpp_sscanf_l(const char *__s, locale_t __l, const char *__format, ...) {
     __libcpp_locale_guard __current(__l);
     int __res = vsscanf(__s, __format, __va);
     va_end(__va);
     return __res;
 }
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // _LIBCPP___BSD_LOCALE_FALLBACKS_H
+#endif // _LIBCPP___LOCALE_LOCALE_BASE_API_BSD_LOCALE_FALLBACKS_H

libcxx/include/__locale_dir/locale_base_api/locale_guard.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___LOCALE_LOCALE_BASE_API_LOCALE_GUARD_H
+#define _LIBCPP___LOCALE_LOCALE_BASE_API_LOCALE_GUARD_H
+
+#include <__config>
+#include <clocale>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if !defined(_LIBCPP_LOCALE__L_EXTENSIONS)
+struct __libcpp_locale_guard {
+  _LIBCPP_INLINE_VISIBILITY __libcpp_locale_guard(locale_t& __loc) : __old_loc_(uselocale(__loc)) {}
+
+  _LIBCPP_INLINE_VISIBILITY ~__libcpp_locale_guard() {
+    if (__old_loc_)
+      uselocale(__old_loc_);
+  }
+
+  locale_t __old_loc_;
+
+private:
+  __libcpp_locale_guard(__libcpp_locale_guard const&);
+  __libcpp_locale_guard& operator=(__libcpp_locale_guard const&);
+};
+#elif defined(_LIBCPP_MSVCRT_LIKE)
+struct __libcpp_locale_guard {
+    __libcpp_locale_guard(locale_t __l) :
+        __status(_configthreadlocale(_ENABLE_PER_THREAD_LOCALE)) {
+      // Setting the locale can be expensive even when the locale given is
+      // already the current locale, so do an explicit check to see if the
+      // current locale is already the one we want.
+      const char* __lc = __setlocale(nullptr);
+      // If every category is the same, the locale string will simply be the
+      // locale name, otherwise it will be a semicolon-separated string listing
+      // each category.  In the second case, we know at least one category won't
+      // be what we want, so we only have to check the first case.
+      if (_VSTD::strcmp(__l.__get_locale(), __lc) != 0) {
+        __locale_all = _strdup(__lc);
+        if (__locale_all == nullptr)
+          __throw_bad_alloc();
+        __setlocale(__l.__get_locale());
+      }
+    }
+    ~__libcpp_locale_guard() {
+      // The CRT documentation doesn't explicitly say, but setlocale() does the
+      // right thing when given a semicolon-separated list of locale settings
+      // for the different categories in the same format as returned by
+      // setlocale(LC_ALL, nullptr).
+      if (__locale_all != nullptr) {
+        __setlocale(__locale_all);
+        free(__locale_all);
+      }
+      _configthreadlocale(__status);
+    }
+    static const char* __setlocale(const char* __locale) {
+      const char* __new_locale = setlocale(LC_ALL, __locale);
+      if (__new_locale == nullptr)
+        __throw_bad_alloc();
+      return __new_locale;
+    }
+    int __status;
+    char* __locale_all = nullptr;
+};
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___LOCALE_LOCALE_BASE_API_LOCALE_GUARD_H

libcxx/include/libcxx.imp

[
   { include: [ "@<__exception/.*>", "private", "<exception>", "public" ] },
   { include: [ "@<__expected/.*>", "private", "<expected>", "public" ] },
   { include: [ "@<__filesystem/.*>", "private", "<filesystem>", "public" ] },
   { include: [ "@<__format/.*>", "private", "<format>", "public" ] },
   { include: [ "@<__functional/.*>", "private", "<functional>", "public" ] },
   { include: [ "@<__fwd/.*>", "private", "<fwd>", "public" ] },
   { include: [ "@<__ios/.*>", "private", "<ios>", "public" ] },
   { include: [ "@<__iterator/.*>", "private", "<iterator>", "public" ] },
+  { include: [ "@<__locale_dir/.*>", "private", "<locale>", "public" ] },
   { include: [ "@<__memory/.*>", "private", "<memory>", "public" ] },
   { include: [ "@<__memory_resource/.*>", "private", "<memory_resource>", "public" ] },
   { include: [ "@<__mutex/.*>", "private", "<mutex>", "public" ] },
   { include: [ "@<__numeric/.*>", "private", "<numeric>", "public" ] },
   { include: [ "@<__random/.*>", "private", "<random>", "public" ] },
   { include: [ "@<__ranges/.*>", "private", "<ranges>", "public" ] },
   { include: [ "@<__string/.*>", "private", "<string>", "public" ] },
   { include: [ "@<__support/.*>", "private", "<support>", "public" ] },
   { include: [ "@<__system_error/.*>", "private", "<system_error>", "public" ] },
   { include: [ "@<__thread/.*>", "private", "<thread>", "public" ] },
   { include: [ "@<__tuple/.*>", "private", "<tuple>", "public" ] },
   { include: [ "@<__type_traits/.*>", "private", "<type_traits>", "public" ] },
   { include: [ "@<__utility/.*>", "private", "<utility>", "public" ] },
   { include: [ "@<__variant/.*>", "private", "<variant>", "public" ] },
 ]

libcxx/include/locale

 // Most unix variants have catopen.  These are the specific ones that don't.
 #  if !defined(__BIONIC__) && !defined(_NEWLIB_VERSION) && !defined(__EMSCRIPTEN__)
 #    define _LIBCPP_HAS_CATOPEN 1
 #    include <nl_types.h>
 #  endif
 #endif
 
 #ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-#include <__bsd_locale_defaults.h>
+#  include <__locale_dir/locale_base_api/bsd_locale_defaults.h>
 #else
-#include <__bsd_locale_fallbacks.h>
+#  include <__locale_dir/locale_base_api/bsd_locale_fallbacks.h>
 #endif
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>

libcxx/src/iostream.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include <__locale>
 #include "std_stream.h"
 #include <new>
 #include <string>
 
+#ifdef _LIBCPP_MSVCRT_LIKE
+#  include <__locale_dir/locale_base_api/locale_guard.h>
+#endif
+
 #define _str(s) #s
 #define str(s) _str(s)
 #define _LIBCPP_ABI_NAMESPACE_STR str(_LIBCPP_ABI_NAMESPACE)
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 _ALIGNAS_TYPE (istream) _LIBCPP_FUNC_VIS char cin[sizeof(istream)]
 #if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)

libcxx/src/support/win32/locale_win32.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include <locale>
 #include <cstdarg> // va_start, va_end
 #include <memory>
 #include <type_traits>
 
+#include <__locale_dir/locale_base_api/locale_guard.h>
+
 int __libcpp_vasprintf(char **sptr, const char *__restrict fmt, va_list ap);
 
 using std::__libcpp_locale_guard;
 
 // FIXME: base currently unused. Needs manual work to construct the new locale
 locale_t newlocale( int mask, const char * locale, locale_t /*base*/ )
 {
     return {_create_locale( LC_ALL, locale ), locale};

libcxx/test/libcxx/lint/lint_modulemap.sh.py

if __name__ == '__main__':
     with open(modulemap_name, 'r') as f:
         for line in f.readlines():
             if re.match(r'^\s*module.*[{]\s*private', line):
                 # Check that these lines are all of the expected format.
                 # This incidentally checks for typos in the module name.
                 if re.match(r'^\s*module (\w+)\s+[{] private header "\1(.h)?"\s+export [*] [}]', line):
                     # It's a top-level private header, such as <__bit_reference>.
                     pass
-                elif re.match(r'^\s*module (\w+)\s+[{] private header "__\w+/\1[.]h" [}]', line):
+                elif re.match(r'^\s*module (\w+)\s+[{] private (textual )?header "__(\w+/)*\1[.]h" [}]', line):
                     # It's a private submodule, such as <__utility/swap.h>.
                     pass
                 elif re.match(r'^\s*module (\w+)_fwd\s+[{] private header "__fwd/\1[.]h" [}]', line):
                     # It's a private submodule with forward declarations, such as <__fwd/span.h>.
                     pass
                 else:
                     okay = False
                     print("LINE DOESN'T MATCH REGEX in libcxx/include/module.modulemap.in!")

libcxx/test/libcxx/private_headers.verify.cpp

for header in private_headers:
   # Skip headers that are not private yet in the modulemap
   if header in private_headers_still_public_in_modules:
     continue
 
   # Skip private headers that start with __support -- those are not in the modulemap yet
   if header.startswith('__support'):
     continue
 
+  # Skip the locale API headers, since they are platform-specific and thus inherently non-modular
+  if 'locale_base_api' in header:
+    continue
+
   print("{ifdef}#{indent}include <{header}> // {expected_error}@*:* {{{{use of private header from outside its module: '{header}'}}}}{endif}".format(
     ifdef='#if ' + header_restrictions[header] + '\n' if header in header_restrictions else '',
     indent='   ' if header in header_restrictions else '',
     header=header,
     expected_error='expected-error',
     endif='\n#endif' if header in header_restrictions else ''
   ))
 

libcxx/test/libcxx/transitive_includes/cxx03.csv

 chrono tuple
 chrono type_traits
 chrono version
 cinttypes cstdint
 cmath type_traits
 cmath version
 codecvt atomic
 codecvt cctype
+codecvt clocale
 codecvt concepts
 codecvt cstddef
 codecvt cstdint
 codecvt cstdlib
 codecvt cstring
+codecvt cwchar
 codecvt initializer_list
 codecvt iosfwd
 codecvt limits
 codecvt mutex
 codecvt new
 codecvt stdexcept
 codecvt string
 codecvt type_traits

 forward_list new
 forward_list stdexcept
 forward_list tuple
 forward_list type_traits
 forward_list typeinfo
 forward_list version
 fstream atomic
 fstream cctype
+fstream clocale
 fstream concepts
 fstream cstddef
 fstream cstdint
 fstream cstdio
 fstream cstdlib
 fstream cstring
+fstream cwchar
 fstream filesystem
 fstream initializer_list
 fstream iosfwd
 fstream istream
 fstream limits
 fstream mutex
 fstream new
 fstream ostream

 future type_traits
 future typeinfo
 future version
 initializer_list cstddef
 iomanip istream
 iomanip version
 ios atomic
 ios cctype
+ios clocale
 ios concepts
 ios cstddef
 ios cstdint
 ios cstdlib
 ios cstring
+ios cwchar
 ios initializer_list
 ios iosfwd
 ios limits
 ios mutex
 ios new
 ios stdexcept
 ios string
 ios system_error

 list stdexcept
 list tuple
 list type_traits
 list typeinfo
 list version
 locale atomic
 locale cctype
 locale cerrno
+locale clocale
 locale concepts
 locale cstdarg
 locale cstddef
 locale cstdint
 locale cstdio
 locale cstdlib
 locale cstring
 locale ctime
+locale cwchar
 locale initializer_list
 locale ios
 locale iosfwd
 locale iterator
 locale limits
 locale mutex
 locale new
 locale stdexcept

 ranges variant
 ranges version
 ratio climits
 ratio cstdint
 ratio type_traits
 ratio version
 regex atomic
 regex cctype
+regex clocale
 regex compare
 regex concepts
 regex cstddef
 regex cstdint
 regex cstdlib
 regex cstring
+regex cwchar
 regex deque
 regex initializer_list
 regex iosfwd
 regex iterator
 regex limits
 regex mutex
 regex new
 regex stdexcept

libcxx/test/libcxx/transitive_includes/cxx11.csv

 chrono tuple
 chrono type_traits
 chrono version
 cinttypes cstdint
 cmath type_traits
 cmath version
 codecvt atomic
 codecvt cctype
+codecvt clocale
 codecvt concepts
 codecvt cstddef
 codecvt cstdint
 codecvt cstdlib
 codecvt cstring
+codecvt cwchar
 codecvt initializer_list
 codecvt iosfwd
 codecvt limits
 codecvt mutex
 codecvt new
 codecvt stdexcept
 codecvt string
 codecvt type_traits

 forward_list new
 forward_list stdexcept
 forward_list tuple
 forward_list type_traits
 forward_list typeinfo
 forward_list version
 fstream atomic
 fstream cctype
+fstream clocale
 fstream concepts
 fstream cstddef
 fstream cstdint
 fstream cstdio
 fstream cstdlib
 fstream cstring
+fstream cwchar
 fstream filesystem
 fstream initializer_list
 fstream iosfwd
 fstream istream
 fstream limits
 fstream mutex
 fstream new
 fstream ostream

 future type_traits
 future typeinfo
 future version
 initializer_list cstddef
 iomanip istream
 iomanip version
 ios atomic
 ios cctype
+ios clocale
 ios concepts
 ios cstddef
 ios cstdint
 ios cstdlib
 ios cstring
+ios cwchar
 ios initializer_list
 ios iosfwd
 ios limits
 ios mutex
 ios new
 ios stdexcept
 ios string
 ios system_error

 list stdexcept
 list tuple
 list type_traits
 list typeinfo
 list version
 locale atomic
 locale cctype
 locale cerrno
+locale clocale
 locale concepts
 locale cstdarg
 locale cstddef
 locale cstdint
 locale cstdio
 locale cstdlib
 locale cstring
 locale ctime
+locale cwchar
 locale initializer_list
 locale ios
 locale iosfwd
 locale iterator
 locale limits
 locale mutex
 locale new
 locale stdexcept

 ranges variant
 ranges version
 ratio climits
 ratio cstdint
 ratio type_traits
 ratio version
 regex atomic
 regex cctype
+regex clocale
 regex compare
 regex concepts
 regex cstddef
 regex cstdint
 regex cstdlib
 regex cstring
+regex cwchar
 regex deque
 regex initializer_list
 regex iosfwd
 regex iterator
 regex limits
 regex mutex
 regex new
 regex stdexcept

libcxx/test/libcxx/transitive_includes/cxx14.csv

 chrono tuple
 chrono type_traits
 chrono version
 cinttypes cstdint
 cmath type_traits
 cmath version
 codecvt atomic
 codecvt cctype
+codecvt clocale
 codecvt concepts
 codecvt cstddef
 codecvt cstdint
 codecvt cstdlib
 codecvt cstring
+codecvt cwchar
 codecvt initializer_list
 codecvt iosfwd
 codecvt limits
 codecvt mutex
 codecvt new
 codecvt stdexcept
 codecvt string
 codecvt type_traits

 forward_list new
 forward_list stdexcept
 forward_list tuple
 forward_list type_traits
 forward_list typeinfo
 forward_list version
 fstream atomic
 fstream cctype
+fstream clocale
 fstream concepts
 fstream cstddef
 fstream cstdint
 fstream cstdio
 fstream cstdlib
 fstream cstring
+fstream cwchar
 fstream filesystem
 fstream initializer_list
 fstream iosfwd
 fstream istream
 fstream limits
 fstream mutex
 fstream new
 fstream ostream

 future type_traits
 future typeinfo
 future version
 initializer_list cstddef
 iomanip istream
 iomanip version
 ios atomic
 ios cctype
+ios clocale
 ios concepts
 ios cstddef
 ios cstdint
 ios cstdlib
 ios cstring
+ios cwchar
 ios initializer_list
 ios iosfwd
 ios limits
 ios mutex
 ios new
 ios stdexcept
 ios string
 ios system_error

 list stdexcept
 list tuple
 list type_traits
 list typeinfo
 list version
 locale atomic
 locale cctype
 locale cerrno
+locale clocale
 locale concepts
 locale cstdarg
 locale cstddef
 locale cstdint
 locale cstdio
 locale cstdlib
 locale cstring
 locale ctime
+locale cwchar
 locale initializer_list
 locale ios
 locale iosfwd
 locale iterator
 locale limits
 locale mutex
 locale new
 locale stdexcept

 ranges variant
 ranges version
 ratio climits
 ratio cstdint
 ratio type_traits
 ratio version
 regex atomic
 regex cctype
+regex clocale
 regex compare
 regex concepts
 regex cstddef
 regex cstdint
 regex cstdlib
 regex cstring
+regex cwchar
 regex deque
 regex initializer_list
 regex iosfwd
 regex iterator
 regex limits
 regex mutex
 regex new
 regex stdexcept

libcxx/test/libcxx/transitive_includes/cxx17.csv

 chrono tuple
 chrono type_traits
 chrono version
 cinttypes cstdint
 cmath type_traits
 cmath version
 codecvt atomic
 codecvt cctype
+codecvt clocale
 codecvt concepts
 codecvt cstddef
 codecvt cstdint
 codecvt cstdlib
 codecvt cstring
+codecvt cwchar
 codecvt initializer_list
 codecvt iosfwd
 codecvt limits
 codecvt mutex
 codecvt new
 codecvt stdexcept
 codecvt string
 codecvt type_traits

 forward_list new
 forward_list stdexcept
 forward_list tuple
 forward_list type_traits
 forward_list typeinfo
 forward_list version
 fstream atomic
 fstream cctype
+fstream clocale
 fstream concepts
 fstream cstddef
 fstream cstdint
 fstream cstdio
 fstream cstdlib
 fstream cstring
+fstream cwchar
 fstream filesystem
 fstream initializer_list
 fstream iosfwd
 fstream istream
 fstream limits
 fstream mutex
 fstream new
 fstream ostream

 future type_traits
 future typeinfo
 future version
 initializer_list cstddef
 iomanip istream
 iomanip version
 ios atomic
 ios cctype
+ios clocale
 ios concepts
 ios cstddef
 ios cstdint
 ios cstdlib
 ios cstring
+ios cwchar
 ios initializer_list
 ios iosfwd
 ios limits
 ios mutex
 ios new
 ios stdexcept
 ios string
 ios system_error

 list stdexcept
 list tuple
 list type_traits
 list typeinfo
 list version
 locale atomic
 locale cctype
 locale cerrno
+locale clocale
 locale concepts
 locale cstdarg
 locale cstddef
 locale cstdint
 locale cstdio
 locale cstdlib
 locale cstring
 locale ctime
+locale cwchar
 locale initializer_list
 locale ios
 locale iosfwd
 locale iterator
 locale limits
 locale mutex
 locale new
 locale stdexcept

 ranges variant
 ranges version
 ratio climits
 ratio cstdint
 ratio type_traits
 ratio version
 regex atomic
 regex cctype
+regex clocale
 regex compare
 regex concepts
 regex cstddef
 regex cstdint
 regex cstdlib
 regex cstring
+regex cwchar
 regex deque
 regex initializer_list
 regex iosfwd
 regex iterator
 regex limits
 regex mutex
 regex new
 regex stdexcept

libcxx/test/libcxx/transitive_includes/cxx20.csv

 chrono type_traits
 chrono vector
 chrono version
 cinttypes cstdint
 cmath type_traits
 cmath version
 codecvt atomic
 codecvt cctype
+codecvt clocale
 codecvt concepts
 codecvt cstddef
 codecvt cstdint
 codecvt cstdlib
 codecvt cstring
+codecvt cwchar
 codecvt initializer_list
 codecvt iosfwd
 codecvt limits
 codecvt mutex
 codecvt new
 codecvt stdexcept
 codecvt string
 codecvt type_traits

 forward_list new
 forward_list stdexcept
 forward_list tuple
 forward_list type_traits
 forward_list typeinfo
 forward_list version
 fstream atomic
 fstream cctype
+fstream clocale
 fstream concepts
 fstream cstddef
 fstream cstdint
 fstream cstdio
 fstream cstdlib
 fstream cstring
+fstream cwchar
 fstream filesystem
 fstream initializer_list
 fstream iosfwd
 fstream istream
 fstream limits
 fstream mutex
 fstream new
 fstream ostream

 future type_traits
 future typeinfo
 future version
 initializer_list cstddef
 iomanip istream
 iomanip version
 ios atomic
 ios cctype
+ios clocale
 ios concepts
 ios cstddef
 ios cstdint
 ios cstdlib
 ios cstring
+ios cwchar
 ios initializer_list
 ios iosfwd
 ios limits
 ios mutex
 ios new
 ios stdexcept
 ios string
 ios system_error

 list stdexcept
 list tuple
 list type_traits
 list typeinfo
 list version
 locale atomic
 locale cctype
 locale cerrno
+locale clocale
 locale concepts
 locale cstdarg
 locale cstddef
 locale cstdint
 locale cstdio
 locale cstdlib
 locale cstring
 locale ctime
+locale cwchar
 locale initializer_list
 locale ios
 locale iosfwd
 locale iterator
 locale limits
 locale mutex
 locale new
 locale stdexcept

 ranges variant
 ranges version
 ratio climits
 ratio cstdint
 ratio type_traits
 ratio version
 regex atomic
 regex cctype
+regex clocale
 regex compare
 regex concepts
 regex cstddef
 regex cstdint
 regex cstdlib
 regex cstring
+regex cwchar
 regex deque
 regex initializer_list
 regex iosfwd
 regex iterator
 regex limits
 regex mutex
 regex new
 regex stdexcept

libcxx/test/libcxx/transitive_includes/cxx2b.csv

 chrono string
 chrono string_view
 chrono tuple
 chrono vector
 chrono version
 cinttypes cstdint
 cmath version
 codecvt cctype
+codecvt clocale
 codecvt cstddef
 codecvt cstdint
 codecvt cstdlib
 codecvt cstring
+codecvt cwchar
 codecvt mutex
 codecvt string
 codecvt version
 compare cmath
 compare cstddef
 compare cstdint
 compare limits
 compare version

 forward_list cstring
 forward_list initializer_list
 forward_list limits
 forward_list new
 forward_list stdexcept
 forward_list tuple
 forward_list version
 fstream cctype
+fstream clocale
 fstream cstddef
 fstream cstdint
 fstream cstdio
 fstream cstdlib
 fstream cstring
+fstream cwchar
 fstream filesystem
 fstream initializer_list
 fstream istream
 fstream mutex
 fstream ostream
 fstream string
 fstream typeinfo
 fstream version

 future string
 future thread
 future typeinfo
 future version
 initializer_list cstddef
 iomanip istream
 iomanip version
 ios cctype
+ios clocale
 ios cstddef
 ios cstdint
 ios cstdlib
 ios cstring
+ios cwchar
 ios iosfwd
 ios mutex
 ios string
 ios version
 iosfwd version
 iostream ios
 iostream istream
 iostream ostream

 list initializer_list
 list limits
 list new
 list stdexcept
 list tuple
 list version
 locale cctype
 locale cerrno
+locale clocale
 locale cstddef
 locale cstdint
 locale cstdio
 locale cstdlib
 locale cstring
 locale ctime
+locale cwchar
 locale initializer_list
 locale ios
 locale iosfwd
 locale limits
 locale mutex
 locale new
 locale streambuf
 locale string

 ranges span
 ranges tuple
 ranges variant
 ranges version
 ratio climits
 ratio cstdint
 ratio version
 regex cctype
+regex clocale
 regex compare
 regex cstddef
 regex cstdint
 regex cstdlib
 regex cstring
+regex cwchar
 regex deque
 regex initializer_list
 regex limits
 regex mutex
 regex stdexcept
 regex string
 regex vector
 regex version

libcxx/utils/data/ignore_format.txt

 libcxx/include/__bit/byteswap.h
 libcxx/include/__bit/countl.h
 libcxx/include/__bit/countr.h
 libcxx/include/__bit/endian.h
 libcxx/include/__bit/popcount.h
 libcxx/include/__bit_reference
 libcxx/include/__bit/rotate.h
 libcxx/include/bitset
-libcxx/include/__bsd_locale_defaults.h
-libcxx/include/__bsd_locale_fallbacks.h
 libcxx/include/cctype
 libcxx/include/chrono
 libcxx/include/__chrono/calendar.h
 libcxx/include/__chrono/convert_to_timespec.h
 libcxx/include/__chrono/day.h
 libcxx/include/__chrono/duration.h
 libcxx/include/__chrono/file_clock.h
 libcxx/include/__chrono/formatter.h

 libcxx/include/__iterator/unreachable_sentinel.h
 libcxx/include/__iterator/wrap_iter.h
 libcxx/include/latch
 libcxx/include/limits
 libcxx/include/limits.h
 libcxx/include/list
 libcxx/include/__locale
 libcxx/include/locale
+libcxx/include/__locale_dir/locale_base_api/bsd_locale_defaults.h
+libcxx/include/__locale_dir/locale_base_api/bsd_locale_fallbacks.h
+libcxx/include/__locale_dir/locale_base_api/locale_guard.h
 libcxx/include/locale.h
 libcxx/include/map
 libcxx/include/math.h
 libcxx/include/__mbstate_t.h
 libcxx/include/memory
 libcxx/include/__memory/addressof.h
 libcxx/include/__memory/aligned_alloc.h
 libcxx/include/__memory/allocate_at_least.h

libcxx/utils/generate_header_tests.py

header_restrictions = {
     "experimental/type_traits": "__cplusplus >= 201103L",
     "experimental/unordered_map": "__cplusplus >= 201103L",
     "experimental/unordered_set": "__cplusplus >= 201103L",
     "experimental/utility": "__cplusplus >= 201103L",
     "experimental/vector": "__cplusplus >= 201103L",
 }
 
 private_headers_still_public_in_modules = [
-    '__assert', '__bsd_locale_defaults.h', '__bsd_locale_fallbacks.h', '__config',
+    '__assert', '__config',
     '__config_site.in', '__debug', '__hash_table',
     '__threading_support', '__tree', '__undef_macros', '__verbose_abort'
 ]
 
 def find_script(file):
     """Finds the script used to generate a file inside the file itself. The script is delimited by
        BEGIN-SCRIPT and END-SCRIPT markers.
     """

libcxx/utils/generate_iwyu_mapping.py

for i in include.iterdir():
         if i.name.startswith('__'):
             detail_files.append(i.name)
             continue
 
         if i.name.endswith('.h'):
             c_headers.append(i.name)
 
     result = []
-    temporary_mappings = {}
+    temporary_mappings = {'__locale_dir' : 'locale'}
     for i in detail_directories:
         public_header = temporary_mappings.get(i, i.lstrip('_'))
         result.append(f'{generate(f"@<{i}/.*>", public_header)},')
 
     for i in detail_files:
         public = []
         if   i == '__assert': continue
         elif i == '__availability': continue
         elif i == '__bit_reference': continue
         elif i == '__bits': public = ['bits']
-        elif i == '__bsd_locale_defaults.h': continue
-        elif i == '__bsd_locale_fallbacks.h': continue
         elif i == '__config_site.in': continue
         elif i == '__config': continue
         elif i == '__debug': continue
         elif i == '__errc': continue
         elif i == '__hash_table': public = ['unordered_map', 'unordered_set']
         elif i == '__locale': public = ['locale']
         elif i == '__mbstate_t.h': continue
         elif i == '__mutex_base': continue