minus.pass.cpp
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//===----------------------------------------------------------------------===//
//
// 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 day;
// constexpr day operator-(const day& x, const days& y) noexcept;
// Returns: x + -y.
//
// constexpr days operator-(const day& x, const day& y) noexcept;
// Returns: days{int(unsigned{x}) - int(unsigned{y}).
#include <chrono>
#include <type_traits>
#include <cassert>
#include "test_macros.h"
template <typename D, typename Ds>
constexpr bool testConstexpr()
{
D d{23};
Ds offset{6};
if (d - offset != D{17}) return false;
if (d - D{17} != offset) return false;
return true;
}
int main(int, char**)
{
using day = std::chrono::day;
using days = std::chrono::days;
ASSERT_NOEXCEPT(std::declval<day>() - std::declval<days>());
ASSERT_NOEXCEPT(std::declval<day>() - std::declval<day>());
ASSERT_SAME_TYPE(day, decltype(std::declval<day>() - std::declval<days>()));
ASSERT_SAME_TYPE(days, decltype(std::declval<day>() - std::declval<day>()));
static_assert(testConstexpr<day, days>(), "");
day dy{12};
for (unsigned i = 0; i <= 10; ++i)
{
day d1 = dy - days{i};
days off = dy - day {i};
assert(static_cast<unsigned>(d1) == 12 - i);
assert(off.count() == static_cast<int>(12 - i)); // days is signed
}
return 0;
}