Mac OS Clang 配置问题

#ifndef _C_LOCALE_H
#define _C_LOCALE_H 1

#pragma GCC system_header

#include <clocale>
#include <cstring>   // get std::strlen
#include <cstdio>    // get std::vsnprintf or std::vsprintf
#include <cstdarg>

#define _GLIBCXX_NUM_CATEGORIES 0

_GLIBCXX_BEGIN_NAMESPACE(std)

  typedef int*          __c_locale;

  // Convert numeric value of type double and long double to string and
  // return length of string.  If vsnprintf is available use it, otherwise
  // fall back to the unsafe vsprintf which, in general, can be dangerous
  // and should be avoided.
  inline int
  __convert_from_v(const __c_locale&, char* __out, 
           const int __size __attribute__((__unused__)),
           const char* __fmt, ...)
  {
    char* __old = std::setlocale(LC_NUMERIC, NULL);
    char* __sav = NULL;
    if (std::strcmp(__old, "C"))
      {
    __sav = new char[std::strlen(__old) + 1];
    std::strcpy(__sav, __old);
    std::setlocale(LC_NUMERIC, "C");
      }

    va_list __args;
    va_start(__args, __fmt);

#ifdef _GLIBCXX_USE_C99
    const int __ret = std::vsnprintf(__out, __size, __fmt, __args);
#else
    const int __ret = std::vsprintf(__out, __fmt, __args);
#endif

    va_end(__args);

    if (__sav)
      {
    std::setlocale(LC_NUMERIC, __sav);
    delete [] __sav;
      }
    return __ret;
  }

_GLIBCXX_END_NAMESPACE

#endif