#include <cstdint>

#include <iomanip>

#include <iostream>

#include <type_traits>

#include <utility>

int main()

{

enum class E1 : char { e };

static_assert(std::is_same_v<char, decltype(std::to_underlying(E1::e))>);

enum struct E2 : long { e };

static_assert(std::is_same_v<long, decltype(std::to_underlying(E2::e))>);

enum E3 : unsigned { e };

static_assert(std::is_same_v<unsigned, decltype(std::to_underlying(e))>);

enum class ColorMask : std::uint32_t {

red = 0xFF, green = (red << 8), blue = (green << 8), alpha = (blue << 8)

};

std::cout << std::hex << std::uppercase << std::setfill('0')

<< std::setw(8) << std::to_underlying(ColorMask::red) << '\n'

<< std::setw(8) << std::to_underlying(ColorMask::green) << '\n'

<< std::setw(8) << std::to_underlying(ColorMask::blue) << '\n'

<< std::setw(8) << std::to_underlying(ColorMask::alpha) << '\n';

// std::underlying_type_t<ColorMask> x = ColorMask::alpha; // Error: no known conversion

[[maybe_unused]]

std::underlying_type_t<ColorMask> y = std::to_underlying(ColorMask::alpha); // OK

}