61 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// UNSUPPORTED: c++03, c++11, c++14, c++179 10// <chrono>11// class month;12 13// constexpr month operator-(const month& x, const months& y) noexcept;14// Returns: x + -y.15//16// constexpr months operator-(const month& x, const month& y) noexcept;17// Returns: If x.ok() == true and y.ok() == true, returns a value m in the range18// [months{0}, months{11}] satisfying y + m == x.19// Otherwise the value returned is unspecified.20// [Example: January - February == months{11}. -end example]21 22#include <chrono>23#include <cassert>24#include <type_traits>25#include <utility>26 27#include "test_macros.h"28 29using month = std::chrono::month;30using months = std::chrono::months;31 32constexpr bool test() {33 month m{6};34 for (unsigned i = 1; i <= 12; ++i) {35 month m1 = m - months{i};36 assert(m1.ok());37 int exp = 6 - i;38 if (exp < 1)39 exp += 12;40 assert(static_cast<unsigned>(m1) == static_cast<unsigned>(exp));41 }42 43 // Check the example44 assert(month{1} - month{2} == months{11});45 46 return true;47}48 49int main(int, char**) {50 ASSERT_NOEXCEPT(std::declval<month>() - std::declval<months>());51 ASSERT_NOEXCEPT(std::declval<month>() - std::declval<month>());52 53 ASSERT_SAME_TYPE(month, decltype(std::declval<month>() - std::declval<months>()));54 ASSERT_SAME_TYPE(months, decltype(std::declval<month>() - std::declval<month>()));55 56 test();57 static_assert(test());58 59 return 0;60}61