//===----------------------------------------------------------------------===//
//
// 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
// <utility>
// template <class T1, class T2> struct pair
// template<class U, class V> pair& operator=(pair<U, V>&& p);
#include <utility>
#include <memory>
#include <cassert>
#include "test_macros.h"
#include "archetypes.h"
struct Derived : ConstexprTestTypes::MoveOnly {
Derived() = default;
TEST_CONSTEXPR_CXX20 Derived(ConstexprTestTypes::MoveOnly&&) {}
};
struct CountAssign {
int copied = 0;
int moved = 0;
TEST_CONSTEXPR_CXX20 CountAssign() = default;
TEST_CONSTEXPR_CXX20 CountAssign(const int) {}
TEST_CONSTEXPR_CXX20 CountAssign& operator=(CountAssign const&) {
++copied;
return *this;
}
TEST_CONSTEXPR_CXX20 CountAssign& operator=(CountAssign&&) {
++moved;
return *this;
}
};
struct CopyAssignableInt {
CopyAssignableInt& operator=(int&) { return *this; }
};
struct NotAssignable {
NotAssignable& operator=(NotAssignable const&) = delete;
NotAssignable& operator=(NotAssignable&&) = delete;
};
struct MoveAssignable {
MoveAssignable& operator=(MoveAssignable const&) = delete;
MoveAssignable& operator=(MoveAssignable&&) = default;
};
struct CopyAssignable {
CopyAssignable& operator=(CopyAssignable const&) = default;
CopyAssignable& operator=(CopyAssignable&&) = delete;
};
TEST_CONSTEXPR_CXX20 bool test() {
{
typedef std::pair<Derived, short> P1;
typedef std::pair<ConstexprTestTypes::MoveOnly, long> P2;
P1 p1(Derived(), static_cast<short>(4));
P2 p2;
p2 = std::move(p1);
assert(p2.second == 4);
}
{
using P = std::pair<int, CountAssign>;
using T = std::pair<long, CountAssign>;
T t(42, -42);
P p(101, 101);
p = std::move(t);
assert(p.first == 42);
assert(p.second.moved == 1);
assert(p.second.copied == 0);
assert(t.second.moved == 0);
assert(t.second.copied == 0);
}
{ // test const requirement
using T = std::pair<CopyAssignableInt, CopyAssignableInt>;
using P = std::pair<int, int>;
static_assert(!std::is_assignable<T&, P&&>::value, "");
static_assert(!std::is_assignable<P&, T&&>::value, "");
}
{
// Make sure we can't move-assign from a pair containing a reference
// if that type isn't copy-constructible (since otherwise we'd be
// stealing the object through the reference).
using P1 = std::pair<MoveAssignable, long>;
using P2 = std::pair<MoveAssignable&, int>;
static_assert(!std::is_assignable<P1&, P2&&>::value, "");
// ... but this should work since we're going to steal out of the
// incoming rvalue reference.
using P3 = std::pair<MoveAssignable, long>;
using P4 = std::pair<MoveAssignable&&, int>;
static_assert(std::is_assignable<P3&, P4&&>::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 P1 = std::pair<MoveAssignable&, long>;
using P2 = std::pair<MoveAssignable&, int>;
static_assert(!std::is_assignable<P1&, P2&&>::value, "");
}
// ... works if it's CopyAssignable
{
using P1 = std::pair<CopyAssignable&, long>;
using P2 = std::pair<CopyAssignable&, int>;
static_assert(std::is_assignable<P1&, P2&&>::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 P1 = std::pair<MoveAssignable&&, long>;
using P2 = std::pair<MoveAssignable&&, int>;
static_assert(std::is_assignable<P1&, P2&&>::value, "");
using P3 = std::pair<CopyAssignable&&, long>;
using P4 = std::pair<CopyAssignable&&, int>;
static_assert(std::is_assignable<P3&, P4&&>::value, "");
}
// In all cases, we can't move-assign if the types are not assignable,
// since we assign through the reference.
{
using P1 = std::pair<NotAssignable&, long>;
using P2 = std::pair<NotAssignable&, int>;
static_assert(!std::is_assignable<P1&, P2&&>::value, "");
using P3 = std::pair<NotAssignable&&, long>;
using P4 = std::pair<NotAssignable&&, int>;
static_assert(!std::is_assignable<P3&, P4&&>::value, "");
}
}
return true;
}
int main(int, char**) {
test();
#if TEST_STD_VER >= 20
static_assert(test());
#endif
return 0;
}