Function strlen

include/string.h:357–367

#  if __has_builtin(__builtin_strlen)
builtin_function(strlen) size_t strlen(FAR const char *s)
{
  if (__builtin_constant_p(s))
    {
      return __builtin_strlen(s);
    }
  else
    {
      return __orig_strlen(s);
    }
}
#  endif

#  if __has_builtin(__builtin_strncat)