test/std/time/time.cal/time.cal.ym/time.cal.ym.members/plus_minus_equal_month.pass.cpp

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17

// <chrono>
// class year_month;

// constexpr year_month& operator+=(const months& d) noexcept;
// constexpr year_month& operator-=(const months& d) noexcept;

#include <chrono>
#include <type_traits>
#include <cassert>

#include "test_macros.h"

using month      = std::chrono::month;
using months     = std::chrono::months;
using year       = std::chrono::year;
using year_month = std::chrono::year_month;

constexpr bool test() {
  for (unsigned i = 0; i <= 10; ++i) {
    year y{1234};
    year_month ym(y, month{i});
    assert(static_cast<unsigned>((ym += months{2}).month()) == i + 2);
    assert(ym.year() == y);
    assert(static_cast<unsigned>((ym).month()) == i + 2);
    assert(ym.year() == y);
    assert(static_cast<unsigned>((ym -= months{1}).month()) == i + 1);
    assert(ym.year() == y);
    assert(static_cast<unsigned>((ym).month()) == i + 1);
    assert(ym.year() == y);
  }

  { // Test year wrapping
    year_month ym{year{2020}, month{4}};

    ym += months{12};
    assert((ym == year_month{year{2021}, month{4}}));

    ym -= months{12};
    assert((ym == year_month{year{2020}, month{4}}));
  }

  return true;
}

int main(int, char**) {
  ASSERT_NOEXCEPT(std::declval<year_month&>() += std::declval<months>());
  ASSERT_SAME_TYPE(year_month&, decltype(std::declval<year_month&>() += std::declval<months>()));

  ASSERT_NOEXCEPT(std::declval<year_month&>() -= std::declval<months>());
  ASSERT_SAME_TYPE(year_month&, decltype(std::declval<year_month&>() -= std::declval<months>()));

  test();
  static_assert(test());

  return 0;
}