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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
// <variant>
// template <class... Types> class variant;
// template <class... Types> requires (three_way_comparable<Types> && ...)
// constexpr std::common_comparison_category_t<
// std::compare_three_way_result_t<Types>...>
// operator<=>(const variant<Types...>& t, const variant<Types...>& u);
#include <cassert>
#include <limits>
#include <type_traits>
#include <utility>
#include <variant>
#include "test_macros.h"
#include "test_comparisons.h"
#ifndef TEST_HAS_NO_EXCEPTIONS
// MakeEmptyT throws in operator=(&&), so we can move to it to create valueless-by-exception variants.
struct MakeEmptyT {
MakeEmptyT() = default;
MakeEmptyT(MakeEmptyT&&) { throw 42; }
MakeEmptyT& operator=(MakeEmptyT&&) { throw 42; }
};
inline bool operator==(const MakeEmptyT&, const MakeEmptyT&) {
assert(false);
return false;
}
inline std::weak_ordering operator<=>(const MakeEmptyT&, const MakeEmptyT&) {
assert(false);
return std::weak_ordering::equivalent;
}
template <class Variant>
void makeEmpty(Variant& v) {
Variant v2(std::in_place_type<MakeEmptyT>);
try {
v = std::move(v2);
assert(false);
} catch (...) {
assert(v.valueless_by_exception());
}
}
void test_empty() {
{
using V = std::variant<int, MakeEmptyT>;
V v1;
V v2;
makeEmpty(v2);
assert(testOrder(v1, v2, std::weak_ordering::greater));
}
{
using V = std::variant<int, MakeEmptyT>;
V v1;
makeEmpty(v1);
V v2;
assert(testOrder(v1, v2, std::weak_ordering::less));
}
{
using V = std::variant<int, MakeEmptyT>;
V v1;
makeEmpty(v1);
V v2;
makeEmpty(v2);
assert(testOrder(v1, v2, std::weak_ordering::equivalent));
}
}
#endif // TEST_HAS_NO_EXCEPTIONS
template <class T1, class T2, class Order>
constexpr bool test_with_types() {
using V = std::variant<T1, T2>;
AssertOrderReturn<Order, V>();
{ // same index, same value
constexpr V v1(std::in_place_index<0>, T1{1});
constexpr V v2(std::in_place_index<0>, T1{1});
assert(testOrder(v1, v2, Order::equivalent));
}
{ // same index, value < other_value
constexpr V v1(std::in_place_index<0>, T1{0});
constexpr V v2(std::in_place_index<0>, T1{1});
assert(testOrder(v1, v2, Order::less));
}
{ // same index, value > other_value
constexpr V v1(std::in_place_index<0>, T1{1});
constexpr V v2(std::in_place_index<0>, T1{0});
assert(testOrder(v1, v2, Order::greater));
}
{ // LHS.index() < RHS.index()
constexpr V v1(std::in_place_index<0>, T1{0});
constexpr V v2(std::in_place_index<1>, T2{0});
assert(testOrder(v1, v2, Order::less));
}
{ // LHS.index() > RHS.index()
constexpr V v1(std::in_place_index<1>, T2{0});
constexpr V v2(std::in_place_index<0>, T1{0});
assert(testOrder(v1, v2, Order::greater));
}
return true;
}
constexpr bool test_three_way() {
assert((test_with_types<int, double, std::partial_ordering>()));
assert((test_with_types<int, long, std::strong_ordering>()));
{
using V = std::variant<int, double>;
constexpr double nan = std::numeric_limits<double>::quiet_NaN();
{
constexpr V v1(std::in_place_type<int>, 1);
constexpr V v2(std::in_place_type<double>, nan);
assert(testOrder(v1, v2, std::partial_ordering::less));
}
{
constexpr V v1(std::in_place_type<double>, nan);
constexpr V v2(std::in_place_type<int>, 2);
assert(testOrder(v1, v2, std::partial_ordering::greater));
}
{
constexpr V v1(std::in_place_type<double>, nan);
constexpr V v2(std::in_place_type<double>, nan);
assert(testOrder(v1, v2, std::partial_ordering::unordered));
}
}
return true;
}
// SFINAE tests
template <class T, class U = T>
concept has_three_way_op = requires (T& t, U& u) { t <=> u; };
// std::three_way_comparable is a more stringent requirement that demands
// operator== and a few other things.
using std::three_way_comparable;
struct HasSimpleOrdering {
constexpr bool operator==(const HasSimpleOrdering&) const;
constexpr bool operator<(const HasSimpleOrdering&) const;
};
struct HasOnlySpaceship {
constexpr bool operator==(const HasOnlySpaceship&) const = delete;
constexpr std::weak_ordering operator<=>(const HasOnlySpaceship&) const;
};
struct HasFullOrdering {
constexpr bool operator==(const HasFullOrdering&) const;
constexpr std::weak_ordering operator<=>(const HasFullOrdering&) const;
};
// operator<=> must resolve the return types of all its union types'
// operator<=>s to determine its own return type, so it is detectable by SFINAE
static_assert(!has_three_way_op<HasSimpleOrdering>);
static_assert(!has_three_way_op<std::variant<int, HasSimpleOrdering>>);
static_assert(!three_way_comparable<HasSimpleOrdering>);
static_assert(!three_way_comparable<std::variant<int, HasSimpleOrdering>>);
static_assert(has_three_way_op<HasOnlySpaceship>);
static_assert(!has_three_way_op<std::variant<int, HasOnlySpaceship>>);
static_assert(!three_way_comparable<HasOnlySpaceship>);
static_assert(!three_way_comparable<std::variant<int, HasOnlySpaceship>>);
static_assert( has_three_way_op<HasFullOrdering>);
static_assert( has_three_way_op<std::variant<int, HasFullOrdering>>);
static_assert( three_way_comparable<HasFullOrdering>);
static_assert( three_way_comparable<std::variant<int, HasFullOrdering>>);
int main(int, char**) {
test_three_way();
static_assert(test_three_way());
#ifndef TEST_HAS_NO_EXCEPTIONS
test_empty();
#endif // TEST_HAS_NO_EXCEPTIONS
return 0;
}
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