//===----------------------------------------------------------------------===//
//
// 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>
// tuple& operator=(tuple<UTypes...>&& u);
// UNSUPPORTED: c++03
#include <tuple>
#include <string>
#include <memory>
#include <utility>
#include <cassert>
#include "test_macros.h"
struct B {
int id_;
explicit B(int i = 0) : id_(i) {}
B(const B&) = default;
B& operator=(const B&) = default;
virtual ~B() {}
};
struct D : B {
explicit D(int i) : B(i) {}
};
struct E {
constexpr E() = default;
TEST_CONSTEXPR_CXX14 E& operator=(int) {
return *this;
}
};
struct NothrowMoveAssignable {
NothrowMoveAssignable& operator=(NothrowMoveAssignable&&) noexcept { return *this; }
};
struct PotentiallyThrowingMoveAssignable {
PotentiallyThrowingMoveAssignable& operator=(PotentiallyThrowingMoveAssignable&&) { return *this; }
};
struct NonAssignable {
NonAssignable& operator=(NonAssignable const&) = delete;
NonAssignable& operator=(NonAssignable&&) = delete;
};
struct MoveAssignable {
MoveAssignable& operator=(MoveAssignable const&) = delete;
MoveAssignable& operator=(MoveAssignable&&) = default;
};
struct CopyAssignable {
CopyAssignable& operator=(CopyAssignable const&) = default;
CopyAssignable& operator=(CopyAssignable&&) = delete;
};
struct TrackMove
{
TrackMove() : value(0), moved_from(false) { }
explicit TrackMove(int v) : value(v), moved_from(false) { }
TrackMove(TrackMove const& other) : value(other.value), moved_from(false) { }
TrackMove(TrackMove&& other) : value(other.value), moved_from(false) {
other.moved_from = true;
}
TrackMove& operator=(TrackMove const& other) {
value = other.value;
moved_from = false;
return *this;
}
TrackMove& operator=(TrackMove&& other) {
value = other.value;
moved_from = false;
other.moved_from = true;
return *this;
}
int value;
bool moved_from;
};
TEST_CONSTEXPR_CXX20
bool test()
{
{
typedef std::tuple<long> T0;
typedef std::tuple<long long> T1;
T0 t0(2);
T1 t1;
t1 = std::move(t0);
assert(std::get<0>(t1) == 2);
}
{
typedef std::tuple<long, char> T0;
typedef std::tuple<long long, int> T1;
T0 t0(2, 'a');
T1 t1;
t1 = std::move(t0);
assert(std::get<0>(t1) == 2);
assert(std::get<1>(t1) == int('a'));
}
{
// Test that tuple evaluates correctly applies an lvalue reference
// before evaluating is_assignable (i.e. 'is_assignable<int&, int&&>')
// instead of evaluating 'is_assignable<int&&, int&&>' which is false.
int x = 42;
int y = 43;
std::tuple<int&&, E> t(std::move(x), E{});
std::tuple<int&&, int> t2(std::move(y), 44);
t = std::move(t2);
assert(std::get<0>(t) == 43);
assert(&std::get<0>(t) == &x);
}
return true;
}
int main(int, char**)
{
test();
#if TEST_STD_VER >= 20
static_assert(test());
#endif
{
typedef std::tuple<long, char, D> T0;
typedef std::tuple<long long, int, B> T1;
T0 t0(2, 'a', D(3));
T1 t1;
t1 = std::move(t0);
assert(std::get<0>(t1) == 2);
assert(std::get<1>(t1) == int('a'));
assert(std::get<2>(t1).id_ == 3);
}
{
D d(3);
D d2(2);
typedef std::tuple<long, char, D&> T0;
typedef std::tuple<long long, int, B&> T1;
T0 t0(2, 'a', d2);
T1 t1(1, 'b', d);
t1 = std::move(t0);
assert(std::get<0>(t1) == 2);
assert(std::get<1>(t1) == int('a'));
assert(std::get<2>(t1).id_ == 2);
}
{
typedef std::tuple<long, char, std::unique_ptr<D>> T0;
typedef std::tuple<long long, int, std::unique_ptr<B>> T1;
T0 t0(2, 'a', std::unique_ptr<D>(new D(3)));
T1 t1;
t1 = std::move(t0);
assert(std::get<0>(t1) == 2);
assert(std::get<1>(t1) == int('a'));
assert(std::get<2>(t1)->id_ == 3);
}
{
using T = std::tuple<int, NonAssignable>;
using U = std::tuple<NonAssignable, int>;
static_assert(!std::is_assignable<T&, U&&>::value, "");
static_assert(!std::is_assignable<U&, T&&>::value, "");
}
{
typedef std::tuple<NothrowMoveAssignable, long> T0;
typedef std::tuple<NothrowMoveAssignable, int> T1;
static_assert(std::is_nothrow_assignable<T0&, T1&&>::value, "");
}
{
typedef std::tuple<PotentiallyThrowingMoveAssignable, long> T0;
typedef std::tuple<PotentiallyThrowingMoveAssignable, int> T1;
static_assert(std::is_assignable<T0&, T1&&>::value, "");
static_assert(!std::is_nothrow_assignable<T0&, T1&&>::value, "");
}
{
// We assign through the reference and don't move out of the incoming ref,
// so this doesn't work (but would if the type were CopyAssignable).
{
using T1 = std::tuple<MoveAssignable&, long>;
using T2 = std::tuple<MoveAssignable&, int>;
static_assert(!std::is_assignable<T1&, T2&&>::value, "");
}
// ... works if it's CopyAssignable
{
using T1 = std::tuple<CopyAssignable&, long>;
using T2 = std::tuple<CopyAssignable&, int>;
static_assert(std::is_assignable<T1&, T2&&>::value, "");
}
// For rvalue-references, we can move-assign if the type is MoveAssignable
// or CopyAssignable (since in the worst case the move will decay into a copy).
{
using T1 = std::tuple<MoveAssignable&&, long>;
using T2 = std::tuple<MoveAssignable&&, int>;
static_assert(std::is_assignable<T1&, T2&&>::value, "");
using T3 = std::tuple<CopyAssignable&&, long>;
using T4 = std::tuple<CopyAssignable&&, int>;
static_assert(std::is_assignable<T3&, T4&&>::value, "");
}
// In all cases, we can't move-assign if the types are not assignable,
// since we assign through the reference.
{
using T1 = std::tuple<NonAssignable&, long>;
using T2 = std::tuple<NonAssignable&, int>;
static_assert(!std::is_assignable<T1&, T2&&>::value, "");
using T3 = std::tuple<NonAssignable&&, long>;
using T4 = std::tuple<NonAssignable&&, int>;
static_assert(!std::is_assignable<T3&, T4&&>::value, "");
}
}
{
// Make sure that we don't incorrectly move out of the source's reference.
using Dest = std::tuple<TrackMove, long>;
using Source = std::tuple<TrackMove&, int>;
TrackMove track{3};
Source src(track, 4);
assert(!track.moved_from);
Dest dst;
dst = std::move(src); // here we should make a copy
assert(!track.moved_from);
assert(std::get<0>(dst).value == 3);
}
{
// But we do move out of the source's reference if it's a rvalue ref
using Dest = std::tuple<TrackMove, long>;
using Source = std::tuple<TrackMove&&, int>;
TrackMove track{3};
Source src(std::move(track), 4);
assert(!track.moved_from); // we just took a reference
Dest dst;
dst = std::move(src);
assert(track.moved_from);
assert(std::get<0>(dst).value == 3);
}
{
// If the source holds a value, then we move out of it too
using Dest = std::tuple<TrackMove, long>;
using Source = std::tuple<TrackMove, int>;
Source src(TrackMove{3}, 4);
Dest dst;
dst = std::move(src);
assert(std::get<0>(src).moved_from);
assert(std::get<0>(dst).value == 3);
}
return 0;
}
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