libcxx: Don't apply ABI tags to extern "C" fns

[ArsenArsen]

Summary

GCC rejects ABI tags on non mangled functions, as they would otherwise
be a no-op. This commit replaces such instances with equivalent
_LIBCPP_HIDE_FROM_ABI constants but without ABI tags attached.

.../include/c++/v1/__support/musl/xlocale.h:28:68: error: 'abi_tag'
attribute applied to extern "C" declaration 'long long int
strtoll_l(const char*, char**, int, locale_t)'
   28 | strtoll_l(const char *__nptr, char **__endptr, int __base, locale_t) {
      |                                                                    ^

Bug: https://bugs.gentoo.org/869038

[ArsenArsen]

Elaborated the commit message a bit. Didn't mean to send out the shortened
one. Sorry about that - still getting adjusted to Arcanist.

[thesamesam]

cc @daltenty re https://reviews.llvm.org/D124227#3473633
cc @brad as author of https://reviews.llvm.org/D124227

[ArsenArsen]

Rebase patch.

[ArsenArsen]

Apply formatting patch from CI.

[ldionne]

LGTM w/ green CI and suggestions applied.

libcxx/include/__config

626–628

Can you define this below with _LIBCPP_HIDE_FROM_ABI_VIRTUAL?

628

Please don't modify this macro -- I know it's possible to "reuse" _LIBCPP_HIDE_FROM_ABI_C to define _LIBCPP_HIDE_FROM_ABI, but IMO adding a layer of indirection there makes things harder to understand. And since that is already extremely tricky, I don't think we should :-).

[ArsenArsen]

libcxx/include/__config

628

My reasoning for this was that the _C macro should reflect exactly the usual macro, save for the ABI tag, and so, reflecting that in the code seemed to make sense.

To save bouncing revisions around, I'll update with this changed, and we can just pick one of the revisions later.

This is also why this macro was awkwardly fit between this comment and conditional block, btw ;D

[ArsenArsen]

Apply suggestions.

libcxx/include/__config

 // function would change, which is incorrect. Note that it doesn't make much sense to change
 // the implementation of a virtual function in an ABI-incompatible way in the first place,
 // since that would be an ABI break anyway. Hence, the lack of ABI tag should not be noticeable.
 //
 // TODO: We provide a escape hatch with _LIBCPP_NO_ABI_TAG for folks who want to avoid increasing
 //       the length of symbols with an ABI tag. In practice, we should remove the escape hatch and
 //       use compression mangling instead, see https://github.com/itanium-cxx-abi/cxx-abi/issues/70.
 #  ifndef _LIBCPP_NO_ABI_TAG
 #    define _LIBCPP_HIDE_FROM_ABI                                                                                      \
       _LIBCPP_HIDDEN _LIBCPP_EXCLUDE_FROM_EXPLICIT_INSTANTIATION                                                       \
           __attribute__((__abi_tag__(_LIBCPP_TOSTRING(_LIBCPP_VERSIONED_IDENTIFIER))))
 #  else
 #    define _LIBCPP_HIDE_FROM_ABI _LIBCPP_HIDDEN _LIBCPP_EXCLUDE_FROM_EXPLICIT_INSTANTIATION
 #  endif
-#    define _LIBCPP_HIDE_FROM_ABI_VIRTUAL _LIBCPP_HIDDEN _LIBCPP_EXCLUDE_FROM_EXPLICIT_INSTANTIATION
+#  define _LIBCPP_HIDE_FROM_ABI_VIRTUAL _LIBCPP_HIDDEN _LIBCPP_EXCLUDE_FROM_EXPLICIT_INSTANTIATION
 
+// This macro provides a HIDE_FROM_ABI equivalent that can be applied to extern
+// "C" function, as those lack mangling.
+#  define _LIBCPP_HIDE_FROM_ABI_C _LIBCPP_HIDDEN _LIBCPP_EXCLUDE_FROM_EXPLICIT_INSTANTIATION
+
 #  ifdef _LIBCPP_BUILDING_LIBRARY
 #    if _LIBCPP_ABI_VERSION > 1
 #      define _LIBCPP_HIDE_FROM_ABI_AFTER_V1 _LIBCPP_HIDE_FROM_ABI
 #    else
 #      define _LIBCPP_HIDE_FROM_ABI_AFTER_V1
 #    endif
 #  else
 #    define _LIBCPP_HIDE_FROM_ABI_AFTER_V1 _LIBCPP_HIDE_FROM_ABI

libcxx/include/__support/android/locale_bionic.h

 #if __ANDROID_API__ < 21
 #include <__support/xlocale/__strtonum_fallback.h>
 #elif __ANDROID_API__ < 26
 
 #if defined(__cplusplus)
 extern "C" {
 #endif
 
-inline _LIBCPP_HIDE_FROM_ABI float
-strtof_l(const char* __nptr, char** __endptr, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C float strtof_l(const char* __nptr, char** __endptr, locale_t) {
   return ::strtof(__nptr, __endptr);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI double
-strtod_l(const char* __nptr, char** __endptr, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C double strtod_l(const char* __nptr, char** __endptr, locale_t) {
   return ::strtod(__nptr, __endptr);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI long
-strtol_l(const char* __nptr, char** __endptr, int __base, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C long strtol_l(const char* __nptr, char** __endptr, int __base, locale_t) {
   return ::strtol(__nptr, __endptr, __base);
 }
 
 #if defined(__cplusplus)
 }
 #endif
 
 #endif // __ANDROID_API__ < 26
 
 #endif // __NDK_MAJOR__ <= 16
 #endif // __has_include(<android/ndk-version.h>)
 #endif // defined(__ANDROID__)
 
 #endif // defined(__BIONIC__)
 #endif // _LIBCPP___SUPPORT_ANDROID_LOCALE_BIONIC_H

libcxx/include/__support/musl/xlocale.h

 
 #include <cstdlib>
 #include <cwchar>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-inline _LIBCPP_HIDE_FROM_ABI long long
-strtoll_l(const char *__nptr, char **__endptr, int __base, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C long long strtoll_l(const char* __nptr, char** __endptr, int __base, locale_t) {
   return ::strtoll(__nptr, __endptr, __base);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI unsigned long long
-strtoull_l(const char *__nptr, char **__endptr, int __base, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C unsigned long long
+strtoull_l(const char* __nptr, char** __endptr, int __base, locale_t) {
   return ::strtoull(__nptr, __endptr, __base);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI long long
-wcstoll_l(const wchar_t *__nptr, wchar_t **__endptr, int __base, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C long long wcstoll_l(const wchar_t* __nptr, wchar_t** __endptr, int __base, locale_t) {
   return ::wcstoll(__nptr, __endptr, __base);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI unsigned long long
-wcstoull_l(const wchar_t *__nptr, wchar_t **__endptr, int __base, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C long long wcstoull_l(const wchar_t* __nptr, wchar_t** __endptr, int __base, locale_t) {
   return ::wcstoull(__nptr, __endptr, __base);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI long double
-wcstold_l(const wchar_t *__nptr, wchar_t **__endptr, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C long double wcstold_l(const wchar_t* __nptr, wchar_t** __endptr, locale_t) {
   return ::wcstold(__nptr, __endptr);
 }
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif // _LIBCPP___SUPPORT_MUSL_XLOCALE_H

libcxx/include/__support/openbsd/xlocale.h

 #include <cstdlib>
 #include <ctype.h>
 #include <cwctype>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-
-inline _LIBCPP_HIDE_FROM_ABI long
-strtol_l(const char *__nptr, char **__endptr, int __base, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C long strtol_l(const char* __nptr, char** __endptr, int __base, locale_t) {
   return ::strtol(__nptr, __endptr, __base);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI unsigned long
-strtoul_l(const char *__nptr, char **__endptr, int __base, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C unsigned long strtoul_l(const char* __nptr, char** __endptr, int __base, locale_t) {
   return ::strtoul(__nptr, __endptr, __base);
 }
 
-
 #ifdef __cplusplus
 }
 #endif
 
 #endif

libcxx/include/__support/xlocale/__nop_locale_mgmt.h

 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 // Patch over lack of extended locale support
 typedef void *locale_t;
 
-inline _LIBCPP_HIDE_FROM_ABI locale_t
-duplocale(locale_t) {
-  return NULL;
-}
-
-inline _LIBCPP_HIDE_FROM_ABI void
-freelocale(locale_t) {
-}
-
-inline _LIBCPP_HIDE_FROM_ABI locale_t
-newlocale(int, const char *, locale_t) {
-  return NULL;
-}
-
-inline _LIBCPP_HIDE_FROM_ABI locale_t
-uselocale(locale_t) {
-  return NULL;
-}
+inline _LIBCPP_HIDE_FROM_ABI_C locale_t duplocale(locale_t) { return NULL; }
+
+inline _LIBCPP_HIDE_FROM_ABI_C void freelocale(locale_t) {}
+
+inline _LIBCPP_HIDE_FROM_ABI_C locale_t newlocale(int, const char*, locale_t) { return NULL; }
+
+inline _LIBCPP_HIDE_FROM_ABI_C locale_t uselocale(locale_t) { return NULL; }
 
 #define LC_COLLATE_MASK  (1 << LC_COLLATE)
 #define LC_CTYPE_MASK    (1 << LC_CTYPE)
 #define LC_MESSAGES_MASK (1 << LC_MESSAGES)
 #define LC_MONETARY_MASK (1 << LC_MONETARY)
 #define LC_NUMERIC_MASK  (1 << LC_NUMERIC)
 #define LC_TIME_MASK     (1 << LC_TIME)
 #define LC_ALL_MASK (LC_COLLATE_MASK|\

libcxx/include/__support/xlocale/__posix_l_fallback.h

 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 #  include <wctype.h>
 #endif
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-inline _LIBCPP_HIDE_FROM_ABI int isalnum_l(int __c, locale_t) {
-  return ::isalnum(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int isalnum_l(int __c, locale_t) { return ::isalnum(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int isalpha_l(int __c, locale_t) {
-  return ::isalpha(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int isalpha_l(int __c, locale_t) { return ::isalpha(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int isblank_l(int __c, locale_t) {
-  return ::isblank(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int isblank_l(int __c, locale_t) { return ::isblank(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int iscntrl_l(int __c, locale_t) {
-  return ::iscntrl(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int iscntrl_l(int __c, locale_t) { return ::iscntrl(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int isdigit_l(int __c, locale_t) {
-  return ::isdigit(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int isdigit_l(int __c, locale_t) { return ::isdigit(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int isgraph_l(int __c, locale_t) {
-  return ::isgraph(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int isgraph_l(int __c, locale_t) { return ::isgraph(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int islower_l(int __c, locale_t) {
-  return ::islower(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int islower_l(int __c, locale_t) { return ::islower(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int isprint_l(int __c, locale_t) {
-  return ::isprint(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int isprint_l(int __c, locale_t) { return ::isprint(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int ispunct_l(int __c, locale_t) {
-  return ::ispunct(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int ispunct_l(int __c, locale_t) { return ::ispunct(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int isspace_l(int __c, locale_t) {
-  return ::isspace(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int isspace_l(int __c, locale_t) { return ::isspace(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int isupper_l(int __c, locale_t) {
-  return ::isupper(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int isupper_l(int __c, locale_t) { return ::isupper(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int isxdigit_l(int __c, locale_t) {
-  return ::isxdigit(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int isxdigit_l(int __c, locale_t) { return ::isxdigit(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int toupper_l(int __c, locale_t) {
-  return ::toupper(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int toupper_l(int __c, locale_t) { return ::toupper(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int tolower_l(int __c, locale_t) {
-  return ::tolower(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int tolower_l(int __c, locale_t) { return ::tolower(__c); }
 
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-inline _LIBCPP_HIDE_FROM_ABI int iswalnum_l(wint_t __c, locale_t) {
-  return ::iswalnum(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int iswalnum_l(wint_t __c, locale_t) { return ::iswalnum(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int iswalpha_l(wint_t __c, locale_t) {
-  return ::iswalpha(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int iswalpha_l(wint_t __c, locale_t) { return ::iswalpha(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int iswblank_l(wint_t __c, locale_t) {
-  return ::iswblank(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int iswblank_l(wint_t __c, locale_t) { return ::iswblank(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int iswcntrl_l(wint_t __c, locale_t) {
-  return ::iswcntrl(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int iswcntrl_l(wint_t __c, locale_t) { return ::iswcntrl(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int iswdigit_l(wint_t __c, locale_t) {
-  return ::iswdigit(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int iswdigit_l(wint_t __c, locale_t) { return ::iswdigit(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int iswgraph_l(wint_t __c, locale_t) {
-  return ::iswgraph(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int iswgraph_l(wint_t __c, locale_t) { return ::iswgraph(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int iswlower_l(wint_t __c, locale_t) {
-  return ::iswlower(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int iswlower_l(wint_t __c, locale_t) { return ::iswlower(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int iswprint_l(wint_t __c, locale_t) {
-  return ::iswprint(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int iswprint_l(wint_t __c, locale_t) { return ::iswprint(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int iswpunct_l(wint_t __c, locale_t) {
-  return ::iswpunct(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int iswpunct_l(wint_t __c, locale_t) { return ::iswpunct(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int iswspace_l(wint_t __c, locale_t) {
-  return ::iswspace(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int iswspace_l(wint_t __c, locale_t) { return ::iswspace(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int iswupper_l(wint_t __c, locale_t) {
-  return ::iswupper(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int iswupper_l(wint_t __c, locale_t) { return ::iswupper(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI int iswxdigit_l(wint_t __c, locale_t) {
-  return ::iswxdigit(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C int iswxdigit_l(wint_t __c, locale_t) { return ::iswxdigit(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI wint_t towupper_l(wint_t __c, locale_t) {
-  return ::towupper(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C wint_t towupper_l(wint_t __c, locale_t) { return ::towupper(__c); }
 
-inline _LIBCPP_HIDE_FROM_ABI wint_t towlower_l(wint_t __c, locale_t) {
-  return ::towlower(__c);
-}
+inline _LIBCPP_HIDE_FROM_ABI_C wint_t towlower_l(wint_t __c, locale_t) { return ::towlower(__c); }
 #endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
 
-inline _LIBCPP_HIDE_FROM_ABI int
-strcoll_l(const char *__s1, const char *__s2, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C int strcoll_l(const char* __s1, const char* __s2, locale_t) {
   return ::strcoll(__s1, __s2);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI size_t
-strxfrm_l(char *__dest, const char *__src, size_t __n, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C size_t strxfrm_l(char* __dest, const char* __src, size_t __n, locale_t) {
   return ::strxfrm(__dest, __src, __n);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI size_t
-strftime_l(char *__s, size_t __max, const char *__format, const struct tm *__tm,
-           locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C size_t
+strftime_l(char* __s, size_t __max, const char* __format, const struct tm* __tm, locale_t) {
   return ::strftime(__s, __max, __format, __tm);
 }
 
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-inline _LIBCPP_HIDE_FROM_ABI int
-wcscoll_l(const wchar_t *__ws1, const wchar_t *__ws2, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C int wcscoll_l(const wchar_t* __ws1, const wchar_t* __ws2, locale_t) {
   return ::wcscoll(__ws1, __ws2);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI size_t
-wcsxfrm_l(wchar_t *__dest, const wchar_t *__src, size_t __n, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C size_t wcsxfrm_l(wchar_t* __dest, const wchar_t* __src, size_t __n, locale_t) {
   return ::wcsxfrm(__dest, __src, __n);
 }
 #endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif // _LIBCPP___SUPPORT_XLOCALE_POSIX_L_FALLBACK_H

libcxx/include/__support/xlocale/__strtonum_fallback.h

 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 #  include <wchar.h>
 #endif
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-inline _LIBCPP_HIDE_FROM_ABI float
-strtof_l(const char *__nptr, char **__endptr, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C float strtof_l(const char* __nptr, char** __endptr, locale_t) {
   return ::strtof(__nptr, __endptr);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI double
-strtod_l(const char *__nptr, char **__endptr, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C double strtod_l(const char* __nptr, char** __endptr, locale_t) {
   return ::strtod(__nptr, __endptr);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI long double
-strtold_l(const char *__nptr, char **__endptr, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C long double strtold_l(const char* __nptr, char** __endptr, locale_t) {
   return ::strtold(__nptr, __endptr);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI long long
-strtoll_l(const char *__nptr, char **__endptr, int __base, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C long long strtoll_l(const char* __nptr, char** __endptr, int __base, locale_t) {
   return ::strtoll(__nptr, __endptr, __base);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI unsigned long long
-strtoull_l(const char *__nptr, char **__endptr, int __base, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C unsigned long long
+strtoull_l(const char* __nptr, char** __endptr, int __base, locale_t) {
   return ::strtoull(__nptr, __endptr, __base);
 }
 
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-inline _LIBCPP_HIDE_FROM_ABI long long
-wcstoll_l(const wchar_t *__nptr, wchar_t **__endptr, int __base, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C long long wcstoll_l(const wchar_t* __nptr, wchar_t** __endptr, int __base, locale_t) {
   return ::wcstoll(__nptr, __endptr, __base);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI unsigned long long
-wcstoull_l(const wchar_t *__nptr, wchar_t **__endptr, int __base, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C unsigned long long
+wcstoull_l(const wchar_t* __nptr, wchar_t** __endptr, int __base, locale_t) {
   return ::wcstoull(__nptr, __endptr, __base);
 }
 
-inline _LIBCPP_HIDE_FROM_ABI long double
-wcstold_l(const wchar_t *__nptr, wchar_t **__endptr, locale_t) {
+inline _LIBCPP_HIDE_FROM_ABI_C long double wcstold_l(const wchar_t* __nptr, wchar_t** __endptr, locale_t) {
   return ::wcstold(__nptr, __endptr);
 }
 #endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif // _LIBCPP___SUPPORT_XLOCALE_STRTONUM_FALLBACK_H