int main()
{
#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
+#if __cplusplus >= 201103L
assert(std::char_traits<char16_t>::length(u"") == 0);
assert(std::char_traits<char16_t>::length(u"a") == 1);
assert(std::char_traits<char16_t>::length(u"aa") == 2);
assert(std::char_traits<char16_t>::length(u"aaa") == 3);
assert(std::char_traits<char16_t>::length(u"aaaa") == 4);
+#endif
#endif // _LIBCPP_HAS_NO_UNICODE_CHARS
}