char8_t test;
char16_t test;
char32_t test;
char8_t test;
int8_t test;
int16_t test;
int32_t test;
int64_t test;
int_fast8_t test;
int_fast16_t test;
int_fast32_t test;
int_fast64_t test;
int_least8_t test;
int_least16_t test;
int_least32_t test;
int_least64_t test;
intmax_t test;
intptr_t test;
uint8_t test;
uint16_t test;
uint32_t test;
uint64_t test;
uint_fast8_t test;
uint_fast16_t test;
uint_fast32_t test;
uint_fast64_t test;
uint_least8_t test;
uint_least16_t test;
uint_least32_t test;
uint_least64_t test;
uintmax_t test;
uintptr_t test;
max_align_t test;
mbstate_t test;
nullptr_t test;
ptrdiff_t test;
size_t test;
wchar_t test;
wctrans_t test;
wctype_t test;
wint_t test;
struct position_tag;
class _thread;
template<class T>
using decay_t = typename decay<T>::type;
template<typename T>
struct X {
using decayed_t = typename std::decay_t<X<T>>;
};
X<int&>::decayed_t x;