libcxx/test/std/utilities/variant/variant.variant/variant.assign/move.pass.cpp

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: c++98, c++03, c++11, c++14

// <variant>

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

// variant& operator=(variant&&) noexcept(see below);

#include <cassert>
#include <string>
#include <type_traits>
#include <utility>
#include <variant>

#include "test_macros.h"
#include "variant_test_helpers.hpp"

struct NoCopy {
  NoCopy(NoCopy const &) = delete;
  NoCopy &operator=(NoCopy const &) = default;
};

struct CopyOnly {
  CopyOnly(CopyOnly const &) = default;
  CopyOnly(CopyOnly &&) = delete;
  CopyOnly &operator=(CopyOnly const &) = default;
  CopyOnly &operator=(CopyOnly &&) = delete;
};

struct MoveOnly {
  MoveOnly(MoveOnly const &) = delete;
  MoveOnly(MoveOnly &&) = default;
  MoveOnly &operator=(MoveOnly const &) = delete;
  MoveOnly &operator=(MoveOnly &&) = default;
};

struct MoveOnlyNT {
  MoveOnlyNT(MoveOnlyNT const &) = delete;
  MoveOnlyNT(MoveOnlyNT &&) {}
  MoveOnlyNT &operator=(MoveOnlyNT const &) = delete;
  MoveOnlyNT &operator=(MoveOnlyNT &&) = default;
};

struct MoveOnlyOddNothrow {
  MoveOnlyOddNothrow(MoveOnlyOddNothrow &&) noexcept(false) {}
  MoveOnlyOddNothrow(MoveOnlyOddNothrow const &) = delete;
  MoveOnlyOddNothrow &operator=(MoveOnlyOddNothrow &&) noexcept = default;
  MoveOnlyOddNothrow &operator=(MoveOnlyOddNothrow const &) = delete;
};

struct MoveAssignOnly {
  MoveAssignOnly(MoveAssignOnly &&) = delete;
  MoveAssignOnly &operator=(MoveAssignOnly &&) = default;
};

struct MoveAssign {
  static int move_construct;
  static int move_assign;
  static void reset() { move_construct = move_assign = 0; }
  MoveAssign(int v) : value(v) {}
  MoveAssign(MoveAssign &&o) : value(o.value) {
    ++move_construct;
    o.value = -1;
  }
  MoveAssign &operator=(MoveAssign &&o) {
    value = o.value;
    ++move_assign;
    o.value = -1;
    return *this;
  }
  int value;
};

int MoveAssign::move_construct = 0;
int MoveAssign::move_assign = 0;

void test_move_assignment_noexcept() {
  {
    using V = std::variant<int>;
    static_assert(std::is_nothrow_move_assignable<V>::value, "");
  }
  {
    using V = std::variant<MoveOnly>;
    static_assert(std::is_nothrow_move_assignable<V>::value, "");
  }
  {
    using V = std::variant<int, long>;
    static_assert(std::is_nothrow_move_assignable<V>::value, "");
  }
  {
    using V = std::variant<int, MoveOnly>;
    static_assert(std::is_nothrow_move_assignable<V>::value, "");
  }
  {
    using V = std::variant<MoveOnlyNT>;
    static_assert(!std::is_nothrow_move_assignable<V>::value, "");
  }
  {
    using V = std::variant<MoveOnlyOddNothrow>;
    static_assert(!std::is_nothrow_move_assignable<V>::value, "");
  }
}

void test_move_assignment_sfinae() {
  {
    using V = std::variant<int, long>;
    static_assert(std::is_move_assignable<V>::value, "");
  }
  {
    // variant only provides move assignment when both the move constructor
    // and move assignment operator are well formed.
    using V = std::variant<int, CopyOnly>;
    static_assert(!std::is_move_assignable<V>::value, "");
  }
  {
    using V = std::variant<int, NoCopy>;
    static_assert(!std::is_move_assignable<V>::value, "");
  }
  {
    using V = std::variant<int, MoveOnly>;
    static_assert(std::is_move_assignable<V>::value, "");
  }
  {
    using V = std::variant<int, MoveOnlyNT>;
    static_assert(std::is_move_assignable<V>::value, "");
  }
  {
    // variant only provides move assignment when the types also provide
    // a move constructor.
    using V = std::variant<int, MoveAssignOnly>;
    static_assert(!std::is_move_assignable<V>::value, "");
  }
}

void test_move_assignment_empty_empty() {
#ifndef TEST_HAS_NO_EXCEPTIONS
  using MET = MakeEmptyT;
  {
    using V = std::variant<int, long, MET>;
    V v1(std::in_place_index<0>);
    makeEmpty(v1);
    V v2(std::in_place_index<0>);
    makeEmpty(v2);
    V &vref = (v1 = std::move(v2));
    assert(&vref == &v1);
    assert(v1.valueless_by_exception());
    assert(v1.index() == std::variant_npos);
  }
#endif
}

void test_move_assignment_non_empty_empty() {
#ifndef TEST_HAS_NO_EXCEPTIONS
  using MET = MakeEmptyT;
  {
    using V = std::variant<int, MET>;
    V v1(std::in_place_index<0>, 42);
    V v2(std::in_place_index<0>);
    makeEmpty(v2);
    V &vref = (v1 = std::move(v2));
    assert(&vref == &v1);
    assert(v1.valueless_by_exception());
    assert(v1.index() == std::variant_npos);
  }
  {
    using V = std::variant<int, MET, std::string>;
    V v1(std::in_place_index<2>, "hello");
    V v2(std::in_place_index<0>);
    makeEmpty(v2);
    V &vref = (v1 = std::move(v2));
    assert(&vref == &v1);
    assert(v1.valueless_by_exception());
    assert(v1.index() == std::variant_npos);
  }
#endif
}

void test_move_assignment_empty_non_empty() {
#ifndef TEST_HAS_NO_EXCEPTIONS
  using MET = MakeEmptyT;
  {
    using V = std::variant<int, MET>;
    V v1(std::in_place_index<0>);
    makeEmpty(v1);
    V v2(std::in_place_index<0>, 42);
    V &vref = (v1 = std::move(v2));
    assert(&vref == &v1);
    assert(v1.index() == 0);
    assert(std::get<0>(v1) == 42);
  }
  {
    using V = std::variant<int, MET, std::string>;
    V v1(std::in_place_index<0>);
    makeEmpty(v1);
    V v2(std::in_place_type<std::string>, "hello");
    V &vref = (v1 = std::move(v2));
    assert(&vref == &v1);
    assert(v1.index() == 2);
    assert(std::get<2>(v1) == "hello");
  }
#endif
}

void test_move_assignment_same_index() {
  {
    using V = std::variant<int>;
    V v1(43);
    V v2(42);
    V &vref = (v1 = std::move(v2));
    assert(&vref == &v1);
    assert(v1.index() == 0);
    assert(std::get<0>(v1) == 42);
  }
  {
    using V = std::variant<int, long, unsigned>;
    V v1(43l);
    V v2(42l);
    V &vref = (v1 = std::move(v2));
    assert(&vref == &v1);
    assert(v1.index() == 1);
    assert(std::get<1>(v1) == 42);
  }
  {
    using V = std::variant<int, MoveAssign, unsigned>;
    V v1(std::in_place_type<MoveAssign>, 43);
    V v2(std::in_place_type<MoveAssign>, 42);
    MoveAssign::reset();
    V &vref = (v1 = std::move(v2));
    assert(&vref == &v1);
    assert(v1.index() == 1);
    assert(std::get<1>(v1).value == 42);
    assert(MoveAssign::move_construct == 0);
    assert(MoveAssign::move_assign == 1);
  }
#ifndef TEST_HAS_NO_EXCEPTIONS
  using MET = MakeEmptyT;
  {
    using V = std::variant<int, MET, std::string>;
    V v1(std::in_place_type<MET>);
    MET &mref = std::get<1>(v1);
    V v2(std::in_place_type<MET>);
    try {
      v1 = std::move(v2);
      assert(false);
    } catch (...) {
    }
    assert(v1.index() == 1);
    assert(&std::get<1>(v1) == &mref);
  }
#endif
}

void test_move_assignment_different_index() {
  {
    using V = std::variant<int, long, unsigned>;
    V v1(43);
    V v2(42l);
    V &vref = (v1 = std::move(v2));
    assert(&vref == &v1);
    assert(v1.index() == 1);
    assert(std::get<1>(v1) == 42);
  }
  {
    using V = std::variant<int, MoveAssign, unsigned>;
    V v1(std::in_place_type<unsigned>, 43);
    V v2(std::in_place_type<MoveAssign>, 42);
    MoveAssign::reset();
    V &vref = (v1 = std::move(v2));
    assert(&vref == &v1);
    assert(v1.index() == 1);
    assert(std::get<1>(v1).value == 42);
    assert(MoveAssign::move_construct == 1);
    assert(MoveAssign::move_assign == 0);
  }
#ifndef TEST_HAS_NO_EXCEPTIONS
  using MET = MakeEmptyT;
  {
    using V = std::variant<int, MET, std::string>;
    V v1(std::in_place_type<int>);
    V v2(std::in_place_type<MET>);
    try {
      v1 = std::move(v2);
      assert(false);
    } catch (...) {
    }
    assert(v1.valueless_by_exception());
    assert(v1.index() == std::variant_npos);
  }
  {
    using V = std::variant<int, MET, std::string>;
    V v1(std::in_place_type<MET>);
    V v2(std::in_place_type<std::string>, "hello");
    V &vref = (v1 = std::move(v2));
    assert(&vref == &v1);
    assert(v1.index() == 2);
    assert(std::get<2>(v1) == "hello");
  }
#endif
}

int main() {
  test_move_assignment_empty_empty();
  test_move_assignment_non_empty_empty();
  test_move_assignment_empty_non_empty();
  test_move_assignment_same_index();
  test_move_assignment_different_index();
  test_move_assignment_sfinae();
  test_move_assignment_noexcept();
}