_LIBCPP_CONSTEXPR
__bitset<_N_words, _Size>::__bitset(unsigned long long __v) _NOEXCEPT
#ifndef _LIBCPP_HAS_NO_CONSTEXPR
-#if __SIZE_WIDTH__ == 64
+#if __SIZEOF_SIZE_T__ == 8
: __first_{__v}
-#elif __SIZE_WIDTH__ == 32
+#elif __SIZEOF_SIZE_T__ == 4
: __first_{__v, __v >> __bits_per_word}
#else
#error This constructor has not been ported to this platform