template<class T, class U>
constexpr bool cmp_equal(T t, U u) noexcept;
using UT = make_unsigned_t<T>; using UU = make_unsigned_t<U>; if constexpr (is_signed_v<T> == is_signed_v<U>) return t == u; else if constexpr (is_signed_v<T>) return t < 0 ? false : UT(t) == u; else return u < 0 ? false : t == UU(u);
template<class T, class U>
constexpr bool cmp_not_equal(T t, U u) noexcept;
template<class T, class U>
constexpr bool cmp_less(T t, U u) noexcept;
using UT = make_unsigned_t<T>; using UU = make_unsigned_t<U>; if constexpr (is_signed_v<T> == is_signed_v<U>) return t < u; else if constexpr (is_signed_v<T>) return t < 0 ? true : UT(t) < u; else return u < 0 ? false : t < UU(u);
template<class T, class U>
constexpr bool cmp_greater(T t, U u) noexcept;
template<class T, class U>
constexpr bool cmp_less_equal(T t, U u) noexcept;
template<class T, class U>
constexpr bool cmp_greater_equal(T t, U u) noexcept;
template<class R, class T>
constexpr bool in_range(T t) noexcept;
return cmp_greater_equal(t, numeric_limits<R>::min()) && cmp_less_equal(t, numeric_limits<R>::max());