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release/20.x: [libc++] Reduce the dependency of the locale base API on the base system from the headers (#117764) #128009

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Merged
merged 2 commits into from
Feb 21, 2025
Merged

release/20.x: [libc++] Reduce the dependency of the locale base API on the base system from the headers (#117764) #128009

merged 2 commits into from
Feb 21, 2025

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@llvmbot llvmbot commented Feb 20, 2025

Backport bcfd9f8 f00b32e

Requested by: @ldionne

@llvmbot llvmbot requested a review from a team as a code owner February 20, 2025 14:32
@llvmbot llvmbot added this to the LLVM 20.X Release milestone Feb 20, 2025
@llvmbot llvmbot mentioned this pull request Feb 20, 2025
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@llvmbot llvmbot added the libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. label Feb 20, 2025
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llvmbot commented Feb 20, 2025

@llvm/pr-subscribers-libcxx

Author: None (llvmbot)

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Backport bcfd9f8 f00b32e

Requested by: @ldionne

Patch is 21.42 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/128009.diff

6 Files Affected:

  • (modified) libcxx/include/__locale_dir/locale_base_api.h (+36-20)
  • (modified) libcxx/include/__locale_dir/support/bsd_like.h (+14-8)
  • (modified) libcxx/include/__locale_dir/support/fuchsia.h (+6-3)
  • (modified) libcxx/include/__locale_dir/support/no_locale/characters.h (+6-2)
  • (modified) libcxx/include/__locale_dir/support/windows.h (+13-5)
  • (added) libcxx/test/libcxx/xopen_source.gen.py (+53)
diff --git a/libcxx/include/__locale_dir/locale_base_api.h b/libcxx/include/__locale_dir/locale_base_api.h
index bbee9f49867fd..c1e73caeecced 100644
--- a/libcxx/include/__locale_dir/locale_base_api.h
+++ b/libcxx/include/__locale_dir/locale_base_api.h
@@ -23,12 +23,16 @@
 // Variadic functions may be implemented as templates with a parameter pack instead
 // of C-style variadic functions.
 //
+// Most of these functions are only required when building the library. Functions that are also
+// required when merely using the headers are marked as such below.
+//
 // TODO: __localeconv shouldn't take a reference, but the Windows implementation doesn't allow copying __locale_t
+// TODO: Eliminate the need for any of these functions from the headers.
 //
 // Locale management
 // -----------------
 // namespace __locale {
-//  using __locale_t = implementation-defined;
+//  using __locale_t = implementation-defined;  // required by the headers
 //  using __lconv_t  = implementation-defined;
 //  __locale_t  __newlocale(int, const char*, __locale_t);
 //  void        __freelocale(__locale_t);
@@ -36,6 +40,7 @@
 //  __lconv_t*  __localeconv(__locale_t&);
 // }
 //
+// // required by the headers
 // #define _LIBCPP_COLLATE_MASK   /* implementation-defined */
 // #define _LIBCPP_CTYPE_MASK     /* implementation-defined */
 // #define _LIBCPP_MONETARY_MASK  /* implementation-defined */
@@ -48,6 +53,7 @@
 // Strtonum functions
 // ------------------
 // namespace __locale {
+//  // required by the headers
 //  float               __strtof(const char*, char**, __locale_t);
 //  double              __strtod(const char*, char**, __locale_t);
 //  long double         __strtold(const char*, char**, __locale_t);
@@ -60,8 +66,8 @@
 // namespace __locale {
 //  int     __islower(int, __locale_t);
 //  int     __isupper(int, __locale_t);
-//  int     __isdigit(int, __locale_t);
-//  int     __isxdigit(int, __locale_t);
+//  int     __isdigit(int, __locale_t);  // required by the headers
+//  int     __isxdigit(int, __locale_t); // required by the headers
 //  int     __toupper(int, __locale_t);
 //  int     __tolower(int, __locale_t);
 //  int     __strcoll(const char*, const char*, __locale_t);
@@ -99,9 +105,10 @@
 //  int     __mbtowc(wchar_t*, const char*, size_t, __locale_t);
 //  size_t  __mbrlen(const char*, size_t, mbstate_t*, __locale_t);
 //  size_t  __mbsrtowcs(wchar_t*, const char**, size_t, mbstate_t*, __locale_t);
-//  int     __snprintf(char*, size_t, __locale_t, const char*, ...);
-//  int     __asprintf(char**, __locale_t, const char*, ...);
-//  int     __sscanf(const char*, __locale_t, const char*, ...);
+//
+//  int     __snprintf(char*, size_t, __locale_t, const char*, ...); // required by the headers
+//  int     __asprintf(char**, __locale_t, const char*, ...);        // required by the headers
+//  int     __sscanf(const char*, __locale_t, const char*, ...);     // required by the headers
 // }
 
 #if defined(__APPLE__)
@@ -143,8 +150,19 @@ namespace __locale {
 //
 // Locale management
 //
+#  define _LIBCPP_COLLATE_MASK LC_COLLATE_MASK
+#  define _LIBCPP_CTYPE_MASK LC_CTYPE_MASK
+#  define _LIBCPP_MONETARY_MASK LC_MONETARY_MASK
+#  define _LIBCPP_NUMERIC_MASK LC_NUMERIC_MASK
+#  define _LIBCPP_TIME_MASK LC_TIME_MASK
+#  define _LIBCPP_MESSAGES_MASK LC_MESSAGES_MASK
+#  define _LIBCPP_ALL_MASK LC_ALL_MASK
+#  define _LIBCPP_LC_ALL LC_ALL
+
 using __locale_t _LIBCPP_NODEBUG = locale_t;
-using __lconv_t _LIBCPP_NODEBUG  = lconv;
+
+#  if defined(_LIBCPP_BUILDING_LIBRARY)
+using __lconv_t _LIBCPP_NODEBUG = lconv;
 
 inline _LIBCPP_HIDE_FROM_ABI __locale_t __newlocale(int __category_mask, const char* __name, __locale_t __loc) {
   return newlocale(__category_mask, __name, __loc);
@@ -157,15 +175,7 @@ inline _LIBCPP_HIDE_FROM_ABI char* __setlocale(int __category, char const* __loc
 inline _LIBCPP_HIDE_FROM_ABI void __freelocale(__locale_t __loc) { freelocale(__loc); }
 
 inline _LIBCPP_HIDE_FROM_ABI __lconv_t* __localeconv(__locale_t& __loc) { return __libcpp_localeconv_l(__loc); }
-
-#  define _LIBCPP_COLLATE_MASK LC_COLLATE_MASK
-#  define _LIBCPP_CTYPE_MASK LC_CTYPE_MASK
-#  define _LIBCPP_MONETARY_MASK LC_MONETARY_MASK
-#  define _LIBCPP_NUMERIC_MASK LC_NUMERIC_MASK
-#  define _LIBCPP_TIME_MASK LC_TIME_MASK
-#  define _LIBCPP_MESSAGES_MASK LC_MESSAGES_MASK
-#  define _LIBCPP_ALL_MASK LC_ALL_MASK
-#  define _LIBCPP_LC_ALL LC_ALL
+#  endif // _LIBCPP_BUILDING_LIBRARY
 
 //
 // Strtonum functions
@@ -194,10 +204,15 @@ __strtoull(const char* __nptr, char** __endptr, int __base, __locale_t __loc) {
 //
 // Character manipulation functions
 //
+#  if defined(_LIBCPP_BUILDING_LIBRARY)
 inline _LIBCPP_HIDE_FROM_ABI int __islower(int __ch, __locale_t __loc) { return islower_l(__ch, __loc); }
 inline _LIBCPP_HIDE_FROM_ABI int __isupper(int __ch, __locale_t __loc) { return isupper_l(__ch, __loc); }
+#  endif
+
 inline _LIBCPP_HIDE_FROM_ABI int __isdigit(int __ch, __locale_t __loc) { return isdigit_l(__ch, __loc); }
 inline _LIBCPP_HIDE_FROM_ABI int __isxdigit(int __ch, __locale_t __loc) { return isxdigit_l(__ch, __loc); }
+
+#  if defined(_LIBCPP_BUILDING_LIBRARY)
 inline _LIBCPP_HIDE_FROM_ABI int __strcoll(const char* __s1, const char* __s2, __locale_t __loc) {
   return strcoll_l(__s1, __s2, __loc);
 }
@@ -207,7 +222,7 @@ inline _LIBCPP_HIDE_FROM_ABI size_t __strxfrm(char* __dest, const char* __src, s
 inline _LIBCPP_HIDE_FROM_ABI int __toupper(int __ch, __locale_t __loc) { return toupper_l(__ch, __loc); }
 inline _LIBCPP_HIDE_FROM_ABI int __tolower(int __ch, __locale_t __loc) { return tolower_l(__ch, __loc); }
 
-#  if _LIBCPP_HAS_WIDE_CHARACTERS
+#    if _LIBCPP_HAS_WIDE_CHARACTERS
 inline _LIBCPP_HIDE_FROM_ABI int __wcscoll(const wchar_t* __s1, const wchar_t* __s2, __locale_t __loc) {
   return wcscoll_l(__s1, __s2, __loc);
 }
@@ -229,7 +244,7 @@ inline _LIBCPP_HIDE_FROM_ABI int __iswpunct(wint_t __ch, __locale_t __loc) { ret
 inline _LIBCPP_HIDE_FROM_ABI int __iswxdigit(wint_t __ch, __locale_t __loc) { return iswxdigit_l(__ch, __loc); }
 inline _LIBCPP_HIDE_FROM_ABI wint_t __towupper(wint_t __ch, __locale_t __loc) { return towupper_l(__ch, __loc); }
 inline _LIBCPP_HIDE_FROM_ABI wint_t __towlower(wint_t __ch, __locale_t __loc) { return towlower_l(__ch, __loc); }
-#  endif
+#    endif
 
 inline _LIBCPP_HIDE_FROM_ABI size_t
 __strftime(char* __s, size_t __max, const char* __format, const tm* __tm, __locale_t __loc) {
@@ -242,7 +257,7 @@ __strftime(char* __s, size_t __max, const char* __format, const tm* __tm, __loca
 inline _LIBCPP_HIDE_FROM_ABI decltype(__libcpp_mb_cur_max_l(__locale_t())) __mb_len_max(__locale_t __loc) {
   return __libcpp_mb_cur_max_l(__loc);
 }
-#  if _LIBCPP_HAS_WIDE_CHARACTERS
+#    if _LIBCPP_HAS_WIDE_CHARACTERS
 inline _LIBCPP_HIDE_FROM_ABI wint_t __btowc(int __ch, __locale_t __loc) { return __libcpp_btowc_l(__ch, __loc); }
 inline _LIBCPP_HIDE_FROM_ABI int __wctob(wint_t __ch, __locale_t __loc) { return __libcpp_wctob_l(__ch, __loc); }
 inline _LIBCPP_HIDE_FROM_ABI size_t
@@ -270,7 +285,8 @@ inline _LIBCPP_HIDE_FROM_ABI size_t
 __mbsrtowcs(wchar_t* __dest, const char** __src, size_t __len, mbstate_t* __ps, __locale_t __loc) {
   return __libcpp_mbsrtowcs_l(__dest, __src, __len, __ps, __loc);
 }
-#  endif
+#    endif // _LIBCPP_HAS_WIDE_CHARACTERS
+#  endif   // _LIBCPP_BUILDING_LIBRARY
 
 _LIBCPP_DIAGNOSTIC_PUSH
 _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wgcc-compat")
diff --git a/libcxx/include/__locale_dir/support/bsd_like.h b/libcxx/include/__locale_dir/support/bsd_like.h
index c0080b13a08cf..405f1589c8c94 100644
--- a/libcxx/include/__locale_dir/support/bsd_like.h
+++ b/libcxx/include/__locale_dir/support/bsd_like.h
@@ -46,7 +46,8 @@ namespace __locale {
 #define _LIBCPP_LC_ALL LC_ALL
 
 using __locale_t = ::locale_t;
-using __lconv_t  = std::lconv;
+#if defined(_LIBCPP_BUILDING_LIBRARY)
+using __lconv_t = std::lconv;
 
 inline _LIBCPP_HIDE_FROM_ABI __locale_t __newlocale(int __category_mask, const char* __locale, __locale_t __base) {
   return ::newlocale(__category_mask, __locale, __base);
@@ -59,6 +60,7 @@ inline _LIBCPP_HIDE_FROM_ABI char* __setlocale(int __category, char const* __loc
 }
 
 inline _LIBCPP_HIDE_FROM_ABI __lconv_t* __localeconv(__locale_t& __loc) { return ::localeconv_l(__loc); }
+#endif // _LIBCPP_BUILDING_LIBRARY
 
 //
 // Strtonum functions
@@ -87,14 +89,17 @@ __strtoull(const char* __nptr, char** __endptr, int __base, __locale_t __loc) {
 //
 // Character manipulation functions
 //
+#if defined(_LIBCPP_BUILDING_LIBRARY)
 inline _LIBCPP_HIDE_FROM_ABI int __islower(int __c, __locale_t __loc) { return ::islower_l(__c, __loc); }
 
 inline _LIBCPP_HIDE_FROM_ABI int __isupper(int __c, __locale_t __loc) { return ::isupper_l(__c, __loc); }
+#endif
 
 inline _LIBCPP_HIDE_FROM_ABI int __isdigit(int __c, __locale_t __loc) { return ::isdigit_l(__c, __loc); }
 
 inline _LIBCPP_HIDE_FROM_ABI int __isxdigit(int __c, __locale_t __loc) { return ::isxdigit_l(__c, __loc); }
 
+#if defined(_LIBCPP_BUILDING_LIBRARY)
 inline _LIBCPP_HIDE_FROM_ABI int __toupper(int __c, __locale_t __loc) { return ::toupper_l(__c, __loc); }
 
 inline _LIBCPP_HIDE_FROM_ABI int __tolower(int __c, __locale_t __loc) { return ::tolower_l(__c, __loc); }
@@ -107,7 +112,7 @@ inline _LIBCPP_HIDE_FROM_ABI size_t __strxfrm(char* __dest, const char* __src, s
   return ::strxfrm_l(__dest, __src, __n, __loc);
 }
 
-#if _LIBCPP_HAS_WIDE_CHARACTERS
+#  if _LIBCPP_HAS_WIDE_CHARACTERS
 inline _LIBCPP_HIDE_FROM_ABI int __iswctype(wint_t __c, wctype_t __type, __locale_t __loc) {
   return ::iswctype_l(__c, __type, __loc);
 }
@@ -143,7 +148,7 @@ inline _LIBCPP_HIDE_FROM_ABI int __wcscoll(const wchar_t* __ws1, const wchar_t*
 inline _LIBCPP_HIDE_FROM_ABI size_t __wcsxfrm(wchar_t* __dest, const wchar_t* __src, size_t __n, __locale_t __loc) {
   return ::wcsxfrm_l(__dest, __src, __n, __loc);
 }
-#endif // _LIBCPP_HAS_WIDE_CHARACTERS
+#  endif // _LIBCPP_HAS_WIDE_CHARACTERS
 
 inline _LIBCPP_HIDE_FROM_ABI size_t
 __strftime(char* __s, size_t __max, const char* __format, const struct tm* __tm, __locale_t __loc) {
@@ -155,14 +160,14 @@ __strftime(char* __s, size_t __max, const char* __format, const struct tm* __tm,
 //
 inline _LIBCPP_HIDE_FROM_ABI decltype(MB_CUR_MAX) __mb_len_max(__locale_t __loc) { return MB_CUR_MAX_L(__loc); }
 
-#if _LIBCPP_HAS_WIDE_CHARACTERS
+#  if _LIBCPP_HAS_WIDE_CHARACTERS
 inline _LIBCPP_HIDE_FROM_ABI wint_t __btowc(int __c, __locale_t __loc) { return ::btowc_l(__c, __loc); }
 
 inline _LIBCPP_HIDE_FROM_ABI int __wctob(wint_t __c, __locale_t __loc) { return ::wctob_l(__c, __loc); }
 
 inline _LIBCPP_HIDE_FROM_ABI size_t
 __wcsnrtombs(char* __dest, const wchar_t** __src, size_t __nwc, size_t __len, mbstate_t* __ps, __locale_t __loc) {
-  return ::wcsnrtombs_l(__dest, __src, __nwc, __len, __ps, __loc);
+  return ::wcsnrtombs_l(__dest, __src, __nwc, __len, __ps, __loc); // wcsnrtombs is a POSIX extension
 }
 
 inline _LIBCPP_HIDE_FROM_ABI size_t __wcrtomb(char* __s, wchar_t __wc, mbstate_t* __ps, __locale_t __loc) {
@@ -171,7 +176,7 @@ inline _LIBCPP_HIDE_FROM_ABI size_t __wcrtomb(char* __s, wchar_t __wc, mbstate_t
 
 inline _LIBCPP_HIDE_FROM_ABI size_t
 __mbsnrtowcs(wchar_t* __dest, const char** __src, size_t __nms, size_t __len, mbstate_t* __ps, __locale_t __loc) {
-  return ::mbsnrtowcs_l(__dest, __src, __nms, __len, __ps, __loc);
+  return ::mbsnrtowcs_l(__dest, __src, __nms, __len, __ps, __loc); // mbsnrtowcs is a POSIX extension
 }
 
 inline _LIBCPP_HIDE_FROM_ABI size_t
@@ -191,7 +196,8 @@ inline _LIBCPP_HIDE_FROM_ABI size_t
 __mbsrtowcs(wchar_t* __dest, const char** __src, size_t __len, mbstate_t* __ps, __locale_t __loc) {
   return ::mbsrtowcs_l(__dest, __src, __len, __ps, __loc);
 }
-#endif
+#  endif // _LIBCPP_HAS_WIDE_CHARACTERS
+#endif   // _LIBCPP_BUILDING_LIBRARY
 
 _LIBCPP_DIAGNOSTIC_PUSH
 _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wgcc-compat")
@@ -211,7 +217,7 @@ _LIBCPP_HIDE_FROM_ABI _LIBCPP_VARIADIC_ATTRIBUTE_FORMAT(__printf__, 4, 5) int __
 template <class... _Args>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_VARIADIC_ATTRIBUTE_FORMAT(__printf__, 3, 4) int __asprintf(
     char** __s, __locale_t __loc, const char* __format, _Args&&... __args) {
-  return ::asprintf_l(__s, __loc, __format, std::forward<_Args>(__args)...);
+  return ::asprintf_l(__s, __loc, __format, std::forward<_Args>(__args)...); // non-standard
 }
 
 template <class... _Args>
diff --git a/libcxx/include/__locale_dir/support/fuchsia.h b/libcxx/include/__locale_dir/support/fuchsia.h
index 237f48562d6e0..fb9de74ab7c7b 100644
--- a/libcxx/include/__locale_dir/support/fuchsia.h
+++ b/libcxx/include/__locale_dir/support/fuchsia.h
@@ -50,7 +50,9 @@ struct __locale_guard {
 #define _LIBCPP_LC_ALL LC_ALL
 
 using __locale_t = locale_t;
-using __lconv_t  = std::lconv;
+
+#if defined(_LIBCPP_BUILDING_LIBRARY)
+using __lconv_t = std::lconv;
 
 inline _LIBCPP_HIDE_FROM_ABI __locale_t __newlocale(int __category_mask, const char* __name, __locale_t __loc) {
   return ::newlocale(__category_mask, __name, __loc);
@@ -74,7 +76,7 @@ inline _LIBCPP_HIDE_FROM_ABI decltype(MB_CUR_MAX) __mb_len_max(__locale_t __loc)
   __locale_guard __current(__loc);
   return MB_CUR_MAX;
 }
-#if _LIBCPP_HAS_WIDE_CHARACTERS
+#  if _LIBCPP_HAS_WIDE_CHARACTERS
 inline _LIBCPP_HIDE_FROM_ABI wint_t __btowc(int __ch, __locale_t __loc) {
   __locale_guard __current(__loc);
   return std::btowc(__ch);
@@ -115,7 +117,8 @@ __mbsrtowcs(wchar_t* __dest, const char** __src, size_t __len, mbstate_t* __ps,
   __locale_guard __current(__loc);
   return ::mbsrtowcs(__dest, __src, __len, __ps);
 }
-#endif
+#  endif // _LIBCPP_HAS_WIDE_CHARACTERS
+#endif   // _LIBCPP_BUILDING_LIBRARY
 
 _LIBCPP_DIAGNOSTIC_PUSH
 _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wgcc-compat")
diff --git a/libcxx/include/__locale_dir/support/no_locale/characters.h b/libcxx/include/__locale_dir/support/no_locale/characters.h
index 20e45fc350e2e..4fb48ed9ceac1 100644
--- a/libcxx/include/__locale_dir/support/no_locale/characters.h
+++ b/libcxx/include/__locale_dir/support/no_locale/characters.h
@@ -29,14 +29,17 @@ namespace __locale {
 //
 // Character manipulation functions
 //
+#if defined(_LIBCPP_BUILDING_LIBRARY)
 inline _LIBCPP_HIDE_FROM_ABI int __islower(int __c, __locale_t) { return std::islower(__c); }
 
 inline _LIBCPP_HIDE_FROM_ABI int __isupper(int __c, __locale_t) { return std::isupper(__c); }
+#endif
 
 inline _LIBCPP_HIDE_FROM_ABI int __isdigit(int __c, __locale_t) { return std::isdigit(__c); }
 
 inline _LIBCPP_HIDE_FROM_ABI int __isxdigit(int __c, __locale_t) { return std::isxdigit(__c); }
 
+#if defined(_LIBCPP_BUILDING_LIBRARY)
 inline _LIBCPP_HIDE_FROM_ABI int __toupper(int __c, __locale_t) { return std::toupper(__c); }
 
 inline _LIBCPP_HIDE_FROM_ABI int __tolower(int __c, __locale_t) { return std::tolower(__c); }
@@ -49,7 +52,7 @@ inline _LIBCPP_HIDE_FROM_ABI size_t __strxfrm(char* __dest, const char* __src, s
   return std::strxfrm(__dest, __src, __n);
 }
 
-#if _LIBCPP_HAS_WIDE_CHARACTERS
+#  if _LIBCPP_HAS_WIDE_CHARACTERS
 inline _LIBCPP_HIDE_FROM_ABI int __iswctype(wint_t __c, wctype_t __type, __locale_t) {
   return std::iswctype(__c, __type);
 }
@@ -85,12 +88,13 @@ inline _LIBCPP_HIDE_FROM_ABI int __wcscoll(const wchar_t* __ws1, const wchar_t*
 inline _LIBCPP_HIDE_FROM_ABI size_t __wcsxfrm(wchar_t* __dest, const wchar_t* __src, size_t __n, __locale_t) {
   return std::wcsxfrm(__dest, __src, __n);
 }
-#endif // _LIBCPP_HAS_WIDE_CHARACTERS
+#  endif // _LIBCPP_HAS_WIDE_CHARACTERS
 
 inline _LIBCPP_HIDE_FROM_ABI size_t
 __strftime(char* __s, size_t __max, const char* __format, const struct tm* __tm, __locale_t) {
   return std::strftime(__s, __max, __format, __tm);
 }
+#endif // _LIBCPP_BUILDING_LIBRARY
 
 } // namespace __locale
 _LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/include/__locale_dir/support/windows.h b/libcxx/include/__locale_dir/support/windows.h
index ff89d3e87eb44..56d34c6f0e6ca 100644
--- a/libcxx/include/__locale_dir/support/windows.h
+++ b/libcxx/include/__locale_dir/support/windows.h
@@ -153,6 +153,7 @@ class __locale_t {
   __lconv_storage* __lc_ = nullptr;
 };
 
+#if defined(_LIBCPP_BUILDING_LIBRARY)
 _LIBCPP_EXPORTED_FROM_ABI __locale_t __newlocale(int __mask, const char* __locale, __locale_t __base);
 inline _LIBCPP_HIDE_FROM_ABI void __freelocale(__locale_t __loc) { ::_free_locale(__loc); }
 inline _LIBCPP_HIDE_FROM_ABI char* __setlocale(int __category, const char* __locale) {
@@ -162,6 +163,7 @@ inline _LIBCPP_HIDE_FROM_ABI char* __setlocale(int __category, const char* __loc
   return __new_locale;
 }
 _LIBCPP_EXPORTED_FROM_ABI __lconv_t* __localeconv(__locale_t& __loc);
+#endif // _LIBCPP_BUILDING_LIBRARY
 
 //
 // Strtonum functions
@@ -195,14 +197,17 @@ __strtoull(const char* __nptr, char** __endptr, int __base, __locale_t __loc) {
 //
 // Character manipulation functions
 //
+#if defined(_LIBCPP_BUILDING_LIBRARY)
 inline _LIBCPP_HIDE_FROM_ABI int __islower(int __c, __locale_t __loc) { return _islower_l(__c, __loc); }
 
 inline _LIBCPP_HIDE_FROM_ABI int __isupper(int __c, __locale_t __loc) { return _isupper_l(__c, __loc); }
+#endif
 
 inline _LIBCPP_HIDE_FROM_ABI int __isdigit(int __c, __locale_t __loc) { return _isdigit_l(__c, __loc); }
 
 inline _LIBCPP_HIDE_FROM_ABI int __isxdigit(int __c, __locale_t __loc) { return _isxdigit_l(__c, __loc); }
 
+#if defined(_LIBCPP_BUILDING_LIBRARY)
 inline _LIBCPP_HIDE_FROM_ABI int __toupper(int __c, __locale_t __loc) { return ::_toupper_l(__c, __loc); }
 
 inline _LIBCPP_HIDE_FROM_ABI int __tolower(int __c, __locale_t __loc) { return ::_tolower_l(__c, __loc); }
@@ -215,7 +220,7 @@ inline _LIBCPP_HIDE_FROM_ABI size_t __strxfrm(char* __dest, const char* __src, s
   return ::_strxfrm_l(__dest, __src, __n, __loc);
 }
 
-#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+#  if _LIBCPP_HAS_WIDE_CHARACTERS
 inline _LIBCPP_HIDE_FROM_ABI int __iswctype(wint_t __c, wctype_t __type, __locale_t __loc) {
   return ::_iswctype_l(__c, __type, __loc);
 }
@@ -240,16 +245,16 @@ inline _LIBCPP_HIDE_FROM_ABI int __wcscoll(const wchar_t* __ws1, const wchar_t*
 inline _LIBCPP_HIDE_FROM_ABI size_t __wcsxfrm(wchar_t* __dest, const wchar_t* __src, size_t __n, __locale_t __loc) {
   return ::_wcsxfrm_l(__dest, __src, __n, __loc);
 }
-#endif // !_LIBCPP_HAS_NO_WIDE_CHARACTERS
+#  endif // _LIBCPP_HAS_WIDE_CHARACTERS
 
-#if defined(__MINGW32__) && __MSVCRT_VERSION__ < 0x0800
+#  if defined(__MINGW32__) && __MSVCRT_VERSION__ < 0x0800
 _LIBCPP_EXPORTED_FROM_ABI size_t __strftime(char*, size_t, const char*, const struct tm*, __locale_t);
-#else
+#  else
 inline _LIBCPP_HIDE_FROM_ABI size_t
 __strftime(char* __ret, size_t __n, const char* __format, const struct tm* __tm, __locale_t __loc) {
   return ::_strftime_l(__ret, __n, __format, __tm, __loc);
 }
-#endif
+#  endif
 
 //
 // Other functions
@@ -273,6 +278,7 @@ _LIBCPP_EXPORTED_FROM_ABI size_t __mbrlen(const char* __restrict, size_t, mbstat
 
 _LIBCPP_EXPORTED_FROM_ABI size_t
 __mbsrtowcs(wchar_t* __restrict, const char** __restrict, size_t, mbstate_t* __restrict, __locale_t);
+#endif // _LIBCPP_BUILDING_LIBRARY
 
 _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_ATTRIBUTE_FORMAT(__printf__, 4, 5) int __snprintf(
     char* __ret, size_t __n, __locale_t __loc, const char* __format, ...);
@@ -297,6 +303,7 @@ _LIBCPP_HIDE_FROM_ABI _LIBCPP_VARIADIC_ATTRIBUTE_FORMAT(__scanf__, 3, 4) int __s
 _LIBCPP_DIAGNOSTIC_POP
 #undef _LIBCPP_VARIADIC_ATTRIBUTE_FORMAT
 
+#if defined(_LIBCPP_BUILDING_LIBRARY)
 struct __locale_guard {
   _LIBCPP_HIDE_FROM_ABI __locale_guard(__locale_t __l) : __status(_configthreadlocale(_ENABLE_PER_THREAD_LOCALE)) {
     // Setting the locale can be expensive even when the locale given is
@@ -328,6 +335,7 @@ struct __locale_guard {
   int __status;
   char* __locale_all = nullptr;
 };
+#endif // _LIBCPP_BUILDING_LIBRARY
 
 } // namespace __locale
 _LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/test/libcxx/xopen_source.gen.py b/libcxx/test/libcxx/xopen_source.gen.py
new file mode 100644
index 0000000000000..3f2686483730a
--- /dev/null
+++ b/libcxx/test/libcxx/xopen_source.gen.py
@@ -0,0 +1,53 @@
+# ===----------------------------------------------------------------------===##
+#
+# 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
+#
+# ===----------------------------------------------------------------------===##
+
+# Make sure that libc++ headers work when defi...
[truncated]

@ldionne @tstellar
[libc++] Fix stray usage of _LIBCPP_HAS_NO_WIDE_CHARACTERS on Windows
af9d7dd 
(cherry picked from commit bcfd9f8)
@ldionne @tstellar
[libc++] Reduce the dependency of the locale base API on the base sys…
43a04b1 
…tem from the headers (llvm#117764)

Many parts of the locale base API are only required when building the
shared/static library, but not from the headers. Document those
functions and carve out a few of those that don't work when
_XOPEN_SOURCE is defined to something old.

Fixes llvm#117630

(cherry picked from commit f00b32e)
@tstellar tstellar merged commit 43a04b1 into llvm:release/20.x Feb 21, 2025
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@ldionne (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR.

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libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi.
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@llvmbot @tstellar @ldionne