third_party/llvm-project/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/UTypes.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
//
//===----------------------------------------------------------------------===//

// <tuple>

// template <class... Types> class tuple;

// template <class... UTypes>
//   explicit tuple(UTypes&&... u);

// UNSUPPORTED: c++03

#include <tuple>
#include <cassert>
#include <type_traits>

#include "test_macros.h"
#include "test_convertible.h"
#include "MoveOnly.h"

#if TEST_STD_VER > 11

struct Empty {};
struct A
{
    int id_;
    explicit constexpr A(int i) : id_(i) {}
};

#endif

struct NoDefault { NoDefault() = delete; };

// Make sure the _Up... constructor SFINAEs out when there are fewer
// constructor arguments than tuple elements.
void test_sfinae_missing_elements()
{
    {
        typedef std::tuple<MoveOnly, NoDefault> Tuple;

        static_assert(!std::is_constructible<
            Tuple,
            MoveOnly
        >::value, "");

        static_assert(std::is_constructible<
            Tuple,
            MoveOnly, NoDefault
        >::value, "");
    }
    {
        typedef std::tuple<MoveOnly, MoveOnly, NoDefault> Tuple;

        static_assert(!std::is_constructible<
            Tuple,
            MoveOnly, MoveOnly
        >::value, "");

        static_assert(std::is_constructible<
            Tuple,
            MoveOnly, MoveOnly, NoDefault
        >::value, "");
    }
    {
        // Same idea as above but with a nested tuple type.
        typedef std::tuple<MoveOnly, NoDefault> Tuple;
        typedef std::tuple<MoveOnly, Tuple, MoveOnly, MoveOnly> NestedTuple;

        static_assert(!std::is_constructible<
            NestedTuple,
            MoveOnly, MoveOnly, MoveOnly, MoveOnly
        >::value, "");

        static_assert(std::is_constructible<
            NestedTuple,
            MoveOnly, Tuple, MoveOnly, MoveOnly
        >::value, "");
    }
}

int main(int, char**)
{
    {
        std::tuple<MoveOnly> t(MoveOnly(0));
        assert(std::get<0>(t) == 0);
    }
    {
        std::tuple<MoveOnly, MoveOnly> t(MoveOnly(0), MoveOnly(1));
        assert(std::get<0>(t) == 0);
        assert(std::get<1>(t) == 1);
    }
    {
        std::tuple<MoveOnly, MoveOnly, MoveOnly> t(MoveOnly(0),
                                                   MoveOnly(1),
                                                   MoveOnly(2));
        assert(std::get<0>(t) == 0);
        assert(std::get<1>(t) == 1);
        assert(std::get<2>(t) == 2);
    }
#if TEST_STD_VER > 11
    {
        constexpr std::tuple<Empty> t0{Empty()};
        (void)t0;
    }
    {
        constexpr std::tuple<A, A> t(3, 2);
        static_assert(std::get<0>(t).id_ == 3, "");
    }
#endif

    test_sfinae_missing_elements();

  return 0;
}