u32.cpp

#include <type_traits>
#include <limits>
#include <cassert>

enum class uint32_t : unsigned int {};

constexpr uint32_t operator""_u32(unsigned long long x) {
    using underlying = std::underlying_type_t<uint32_t>;
    assert(static_cast<unsigned long long>(std::numeric_limits<underlying>::max()) >= x);
    return uint32_t{static_cast<underlying>(x)};
}

template<typename T, typename... Args>
constexpr bool is_one_of = std::disjunction_v<std::is_same<T, Args>...>;

template<typename T>
concept bool Integral = is_one_of<T, uint32_t>;

template<Integral T>
constexpr T operator+ (T lhs, T rhs) noexcept
{
    using underlying = std::underlying_type_t<uint32_t>;
    return T{static_cast<underlying>(lhs) + static_cast<underlying>(rhs)};
}

int main() {
    auto x = 1_u32;
    auto y = x + 2_u32;
    assert(x + y == 4_u32);
}