[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

 #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___SUPPORT_XLOCALE_BSD_LOCALE_DEFAULTS_H
+#define _LIBCPP___SUPPORT_XLOCALE_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___SUPPORT_XLOCALE_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___SUPPORT_XLOCALE_BSD_LOCALE_FALLBACKS_H
+#define _LIBCPP___SUPPORT_XLOCALE_BSD_LOCALE_FALLBACKS_H
 
+#include <__locale_dir/locale_base_api/locale_guard.h>
+#include <cstdio>
+#include <cwchar>
 #include <stdarg.h>
 #include <stdlib.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
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___SUPPORT_XLOCALE_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: [ "@<__thread/.*>", "private", "<thread>", "public" ] },
   { include: [ "@<__tuple_dir/.*>", "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/include/module.modulemap.in

module list {
     header "list"
     export initializer_list
     export *
   }
   module locale {
     @requires_LIBCXX_ENABLE_LOCALIZATION@
     header "locale"
     export *
+
+    module __locale {
+      module locale_base_api {
+        // These headers are inherently textual, since they define platform-specific code.
+        module bsd_locale_defaults  { private textual header "__locale_dir/locale_base_api/bsd_locale_defaults.h" }
+        module bsd_locale_fallbacks { private textual header "__locale_dir/locale_base_api/bsd_locale_fallbacks.h" }
+        module locale_guard         { private textual header "__locale_dir/locale_base_api/locale_guard.h" }
+      }
+    }
   }
   module map {
     header "map"
     export initializer_list
     export *
   }
   module memory {
     header "memory"

libcxx/test/libcxx/private_headers.verify.cpp

 #include <__iterator/reverse_access.h> // expected-error@*:* {{use of private header from outside its module: '__iterator/reverse_access.h'}}
 #include <__iterator/reverse_iterator.h> // expected-error@*:* {{use of private header from outside its module: '__iterator/reverse_iterator.h'}}
 #include <__iterator/segmented_iterator.h> // expected-error@*:* {{use of private header from outside its module: '__iterator/segmented_iterator.h'}}
 #include <__iterator/size.h> // expected-error@*:* {{use of private header from outside its module: '__iterator/size.h'}}
 #include <__iterator/sortable.h> // expected-error@*:* {{use of private header from outside its module: '__iterator/sortable.h'}}
 #include <__iterator/unreachable_sentinel.h> // expected-error@*:* {{use of private header from outside its module: '__iterator/unreachable_sentinel.h'}}
 #include <__iterator/wrap_iter.h> // expected-error@*:* {{use of private header from outside its module: '__iterator/wrap_iter.h'}}
 #include <__locale> // expected-error@*:* {{use of private header from outside its module: '__locale'}}
+#include <__locale_dir/locale_base_api/bsd_locale_defaults.h> // expected-error@*:* {{use of private header from outside its module: '__locale_dir/locale_base_api/bsd_locale_defaults.h'}}
+#include <__locale_dir/locale_base_api/bsd_locale_fallbacks.h> // expected-error@*:* {{use of private header from outside its module: '__locale_dir/locale_base_api/bsd_locale_fallbacks.h'}}
+#include <__locale_dir/locale_base_api/locale_guard.h> // expected-error@*:* {{use of private header from outside its module: '__locale_dir/locale_base_api/locale_guard.h'}}
 #include <__mbstate_t.h> // expected-error@*:* {{use of private header from outside its module: '__mbstate_t.h'}}
 #include <__memory/addressof.h> // expected-error@*:* {{use of private header from outside its module: '__memory/addressof.h'}}
 #include <__memory/align.h> // expected-error@*:* {{use of private header from outside its module: '__memory/align.h'}}
 #include <__memory/aligned_alloc.h> // expected-error@*:* {{use of private header from outside its module: '__memory/aligned_alloc.h'}}
 #include <__memory/allocate_at_least.h> // expected-error@*:* {{use of private header from outside its module: '__memory/allocate_at_least.h'}}
 #include <__memory/allocation_guard.h> // expected-error@*:* {{use of private header from outside its module: '__memory/allocation_guard.h'}}
 #include <__memory/allocator.h> // expected-error@*:* {{use of private header from outside its module: '__memory/allocator.h'}}
 #include <__memory/allocator_arg_t.h> // expected-error@*:* {{use of private header from outside its module: '__memory/allocator_arg_t.h'}}

libcxx/test/libcxx/transitive_includes/cxx03.csv

 list new
 list stdexcept
 list tuple
 list type_traits
 list typeinfo
 list version
 locale atomic
 locale cctype
+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

libcxx/test/libcxx/transitive_includes/cxx11.csv

 list new
 list stdexcept
 list tuple
 list type_traits
 list typeinfo
 list version
 locale atomic
 locale cctype
+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

libcxx/test/libcxx/transitive_includes/cxx14.csv

 list new
 list stdexcept
 list tuple
 list type_traits
 list typeinfo
 list version
 locale atomic
 locale cctype
+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

libcxx/test/libcxx/transitive_includes/cxx17.csv

 list new
 list stdexcept
 list tuple
 list type_traits
 list typeinfo
 list version
 locale atomic
 locale cctype
+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

libcxx/test/libcxx/transitive_includes/cxx20.csv

 list new
 list stdexcept
 list tuple
 list type_traits
 list typeinfo
 list version
 locale atomic
 locale cctype
+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

libcxx/test/libcxx/transitive_includes/cxx2b.csv

 list cstring
 list initializer_list
 list limits
 list new
 list stdexcept
 list tuple
 list version
 locale cctype
+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

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 = {'__tuple_dir': 'tuple'}
+    temporary_mappings = {'__tuple_dir': 'tuple', '__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