#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE == 1
 #undef _POSIX_C_SOURCE
 #define _POSIX_C_SOURCE 199009
#endif

#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE == 2
 #undef _POSIX_C_SOURCE
 #define _POSIX_C_SOURCE 199209
#endif

#ifdef _XOPEN_SOURCE
 #if _XOPEN_SOURCE - 0 >= 700
  #define __XSI_VISIBLE 700
  #undef _POSIX_C_SOURCE
  #define _POSIX_C_SOURCE 200809
 #elif _XOPEN_SOURCE - 0 >= 600
  #define __XSI_VISIBLE 600
  #undef _POSIX_C_SOURCE
  #define _POSIX_C_SOURCE 200112
 #elif _XOPEN_SOURCE - 0 >= 500
  #define __XSI_VISIBLE 500
  #undef _POSIX_C_SOURCE
  #define _POSIX_C_SOURCE 199506
 #endif
#endif

#if defined(_POSIX_SOURCE) && !defined(_POSIX_C_SOURCE)
 #define _POSIX_C_SOURCE 198808
#endif

#ifdef _POSIX_C_SOURCE
 #if _POSIX_C_SOURCE >= 200809
  #define __POSIX_VISIBLE 200809
  #define __ISO_C_VISIBLE 1999
 #elif _POSIX_C_SOURCE >= 200112
  #define __POSIX_VISIBLE 200112
  #define __ISO_C_VISIBLE 1999
 #elif _POSIX_C_SOURCE >= 199506
  #define __POSIX_VISIBLE 199506
  #define __ISO_C_VISIBLE 1990
 #elif _POSIX_C_SOURCE >= 199309
  #define __POSIX_VISIBLE 199309
  #define __ISO_C_VISIBLE 1990
 #elif _POSIX_C_SOURCE >= 199209
  #define __POSIX_VISIBLE 199209
  #define __ISO_C_VISIBLE 1990
 #elif _POSIX_C_SOURCE >= 199009
  #define __POSIX_VISIBLE 199009
  #define __ISO_C_VISIBLE 1990
 #else
  #define __POSIX_VISIBLE 198808
  #define __ISO_C_VISIBLE 0
 #endif
#else
 #if defined(_ANSI_SOURCE)
  #define __POSIX_VISIBLE 0
  #define __XSI_VISIBLE 0
  #define __BSD_VISIBLE 0
  #define __ISO_C_VISIBLE 1990
 #elif defined(_C99_SOURCE)
  #define __POSIX_VISIBLE 0
  #define __XSI_VISIBLE 0
  #define __BSD_VISIBLE 0
  #define __ISO_C_VISIBLE 1999
 #elif defined(_C11_SOURCE)
  #define __POSIX_VISIBLE 0
  #define __XSI_VISIBLE 0
  #define __BSD_VISIBLE 0
  #define __ISO_C_VISIBLE 2011
 #else
  #define __POSIX_VISIBLE 200809
  #define __XSI_VISIBLE 700
  #define __BSD_VISIBLE 1
  #define __ISO_C_VISIBLE 2011
 #endif
#endif