86 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9// UNSUPPORTED: c++03, c++11, c++14, c++17, c++2010 11// [utility.underlying], to_underlying12// template <class T>13// constexpr underlying_type_t<T> to_underlying( T value ) noexcept; // C++2314 15#include <utility>16#include <cassert>17#include <cstdint>18#include <limits>19 20#include "test_macros.h"21 22enum class e_default { a = 0, b = 1, c = 2 };23enum class e_ushort : unsigned short { d = 10, e = 25, f = 50 };24enum class e_longlong : long long {25 low = std::numeric_limits<long long>::min(),26 high = std::numeric_limits<long long>::max()27};28enum e_non_class { enum_a = 10, enum_b = 11, enum_c = 12 };29enum e_int : int {30 enum_min = std::numeric_limits<int>::min(),31 enum_max = std::numeric_limits<int>::max()32};33enum class e_bool : std::uint8_t { f = 0, t = 1 };34 35struct WithBitfieldEnums {36 e_default e1 : 3;37 e_ushort e2 : 6;38 e_bool e3 : 1;39};40 41constexpr bool test() {42 ASSERT_NOEXCEPT(std::to_underlying(e_default::a));43 ASSERT_SAME_TYPE(int, decltype(std::to_underlying(e_default::a)));44 ASSERT_SAME_TYPE(unsigned short, decltype(std::to_underlying(e_ushort::d)));45 ASSERT_SAME_TYPE(long long, decltype(std::to_underlying(e_longlong::low)));46 ASSERT_SAME_TYPE(int, decltype(std::to_underlying(enum_min)));47 ASSERT_SAME_TYPE(int, decltype(std::to_underlying(enum_max)));48 49 assert(0 == std::to_underlying(e_default::a));50 assert(1 == std::to_underlying(e_default::b));51 assert(2 == std::to_underlying(e_default::c));52 53 assert(10 == std::to_underlying(e_ushort::d));54 assert(25 == std::to_underlying(e_ushort::e));55 assert(50 == std::to_underlying(e_ushort::f));56 57 // Check no truncating.58 assert(std::numeric_limits<long long>::min() ==59 std::to_underlying(e_longlong::low));60 assert(std::numeric_limits<long long>::max() ==61 std::to_underlying(e_longlong::high));62 63 assert(10 == std::to_underlying(enum_a));64 assert(11 == std::to_underlying(enum_b));65 assert(12 == std::to_underlying(enum_c));66 assert(std::numeric_limits<int>::min() == std::to_underlying(enum_min));67 assert(std::numeric_limits<int>::max() == std::to_underlying(enum_max));68 69 WithBitfieldEnums bf;70 bf.e1 = static_cast<e_default>(3);71 bf.e2 = e_ushort::e;72 bf.e3 = e_bool::t;73 assert(3 == std::to_underlying(bf.e1));74 assert(25 == std::to_underlying(bf.e2));75 assert(1 == std::to_underlying(bf.e3));76 77 return true;78}79 80int main(int, char**) {81 test();82 static_assert(test());83 84 return 0;85}86