//===----------------------------------------------------------------------===//
//
// 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
// <compare>
// template <class ...Ts> struct common_comparison_category
// template <class ...Ts> using common_comparison_category_t
#include <compare>
#include <type_traits>
#include <cassert>
#include "test_macros.h"
const volatile void* volatile sink;
template <class Expect, class ...Args>
void test_cat() {
using Cat = std::common_comparison_category<Args...>;
using CatT = typename Cat::type;
static_assert(std::is_same<CatT, std::common_comparison_category_t<Args...>>::value, "");
static_assert(std::is_same<CatT, Expect>::value, "expected different category");
};
// [class.spaceship]p4: The 'common comparison type' U of a possibly-empty list
// of 'n' types T0, T1, ..., TN, is defined as follows:
int main(int, char**) {
using PO = std::partial_ordering;
using WO = std::weak_ordering;
using SO = std::strong_ordering;
// [cmp.common]p2: The member typedef-name type denotes the common comparison
/// type ([class.spaceship]) of Ts..., the expanded parameter pack, or void if
// any element of Ts is not a comparison category type.
{
test_cat<void, void>();
test_cat<void, int*>();
test_cat<void, SO&>();
test_cat<void, SO const>();
test_cat<void, SO*>();
test_cat<void, SO, void, SO>();
}
// [class.spaceship]p4.1: If at least one Ti is std::partial_ordering, U is
// std::partial_ordering ([cmp.partialord]).
{
test_cat<PO, PO>();
test_cat<PO, SO, PO, SO>();
test_cat<PO, WO, PO, SO>();
}
// [class.spaceship]p4.2: Otherwise, if at least one Ti is std::weak_ordering,
// U is std::weak_ordering
{
test_cat<WO, WO>();
test_cat<WO, SO, WO, SO>();
}
// [class.spaceship]p4.3: Otherwise, U is std::strong_ordering.
{
test_cat<SO, SO>();
test_cat<SO, SO, SO>();
}
// [cmp.common]p2, note 2: This is std::strong_ordering if the expansion is empty.
// [class.spaceship]p4.3, note 2: In particular this is the result when n is 0.
{
test_cat<SO>(); // empty type list
}
return 0;
}