//===----------------------------------------------------------------------===//
//
// 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: msvc-19.16
// UNSUPPORTED: clang-7, clang-8

// <cuda/std/variant>

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

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

#include <cuda/std/cassert>
#if defined(_LIBCUDACXX_HAS_STRING)
// #include <cuda/std/string>
#endif // _LIBCUDACXX_HAS_STRING
#include <cuda/std/type_traits>
#include <cuda/std/utility>
#include <cuda/std/variant>

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

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

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

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

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

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

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

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

struct NTMoveAssign
{
  __host__ __device__ constexpr NTMoveAssign(int v)
      : value(v)
  {}
  NTMoveAssign(const NTMoveAssign&)                 = default;
  NTMoveAssign(NTMoveAssign&&)                      = default;
  NTMoveAssign& operator=(const NTMoveAssign& that) = default;
  __host__ __device__ NTMoveAssign& operator=(NTMoveAssign&& that)
  {
    value      = that.value;
    that.value = -1;
    return *this;
  };
  int value;
};

static_assert(!cuda::std::is_trivially_move_assignable<NTMoveAssign>::value, "");
static_assert(cuda::std::is_move_assignable<NTMoveAssign>::value, "");

struct TMoveAssign
{
  __host__ __device__ constexpr TMoveAssign(int v)
      : value(v)
  {}
  TMoveAssign(const TMoveAssign&)            = delete;
  TMoveAssign(TMoveAssign&&)                 = default;
  TMoveAssign& operator=(const TMoveAssign&) = delete;
  TMoveAssign& operator=(TMoveAssign&&)      = default;
  int value;
};

static_assert(cuda::std::is_trivially_move_assignable<TMoveAssign>::value, "");

struct TMoveAssignNTCopyAssign
{
  __host__ __device__ constexpr TMoveAssignNTCopyAssign(int v)
      : value(v)
  {}
  TMoveAssignNTCopyAssign(const TMoveAssignNTCopyAssign&) = default;
  TMoveAssignNTCopyAssign(TMoveAssignNTCopyAssign&&)      = default;
  __host__ __device__ TMoveAssignNTCopyAssign& operator=(const TMoveAssignNTCopyAssign& that)
  {
    value = that.value;
    return *this;
  }
  TMoveAssignNTCopyAssign& operator=(TMoveAssignNTCopyAssign&&) = default;
  int value;
};

static_assert(cuda::std::is_trivially_move_assignable_v<TMoveAssignNTCopyAssign>, "");

struct TrivialCopyNontrivialMove
{
  TrivialCopyNontrivialMove(TrivialCopyNontrivialMove const&) = default;
  __host__ __device__ TrivialCopyNontrivialMove(TrivialCopyNontrivialMove&&) noexcept {}
  TrivialCopyNontrivialMove& operator=(TrivialCopyNontrivialMove const&) = default;
  __host__ __device__ TrivialCopyNontrivialMove& operator=(TrivialCopyNontrivialMove&&) noexcept
  {
    return *this;
  }
};

static_assert(cuda::std::is_trivially_copy_assignable_v<TrivialCopyNontrivialMove>, "");
static_assert(!cuda::std::is_trivially_move_assignable_v<TrivialCopyNontrivialMove>, "");

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

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

  // Make sure we properly propagate triviality (see P0602R4).
  {
    using V = cuda::std::variant<int, long>;
    static_assert(cuda::std::is_trivially_move_assignable<V>::value, "");
  }
  {
    using V = cuda::std::variant<int, NTMoveAssign>;
    static_assert(!cuda::std::is_trivially_move_assignable<V>::value, "");
    static_assert(cuda::std::is_move_assignable<V>::value, "");
  }
  {
    using V = cuda::std::variant<int, TMoveAssign>;
    static_assert(cuda::std::is_trivially_move_assignable<V>::value, "");
  }
  {
    using V = cuda::std::variant<int, TMoveAssignNTCopyAssign>;
    static_assert(cuda::std::is_trivially_move_assignable<V>::value, "");
  }
  {
    using V = cuda::std::variant<int, TrivialCopyNontrivialMove>;
    static_assert(!cuda::std::is_trivially_move_assignable<V>::value, "");
  }
  {
    using V = cuda::std::variant<int, CopyOnly>;
    static_assert(cuda::std::is_trivially_move_assignable<V>::value, "");
  }
}

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

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

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

template <typename T>
struct Result
{
  size_t index;
  T value;
};

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

  // Make sure we properly propagate triviality, which implies constexpr-ness (see P0602R4).
  {
    struct
    {
      __host__ __device__ constexpr Result<int> operator()() const
      {
        using V = cuda::std::variant<int>;
        V v(43);
        V v2(42);
        v = cuda::std::move(v2);
        return {v.index(), cuda::std::get<0>(v)};
      }
    } test;
    constexpr auto result = test();
    static_assert(result.index == 0, "");
    static_assert(result.value == 42, "");
  }
  {
    struct
    {
      __host__ __device__ constexpr Result<long> operator()() const
      {
        using V = cuda::std::variant<int, long, unsigned>;
        V v(43l);
        V v2(42l);
        v = cuda::std::move(v2);
        return {v.index(), cuda::std::get<1>(v)};
      }
    } test;
    constexpr auto result = test();
    static_assert(result.index == 1, "");
    static_assert(result.value == 42l, "");
  }
  {
    struct
    {
      __host__ __device__ constexpr Result<int> operator()() const
      {
        using V = cuda::std::variant<int, TMoveAssign, unsigned>;
        V v(cuda::std::in_place_type<TMoveAssign>, 43);
        V v2(cuda::std::in_place_type<TMoveAssign>, 42);
        v = cuda::std::move(v2);
        return {v.index(), cuda::std::get<1>(v).value};
      }
    } test;
    constexpr auto result = test();
    static_assert(result.index == 1, "");
    static_assert(result.value == 42, "");
  }
}

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

  // Make sure we properly propagate triviality, which implies constexpr-ness (see P0602R4).
  {
    struct
    {
      __host__ __device__ constexpr Result<long> operator()() const
      {
        using V = cuda::std::variant<int, long, unsigned>;
        V v(43);
        V v2(42l);
        v = cuda::std::move(v2);
        return {v.index(), cuda::std::get<1>(v)};
      }
    } test;
    constexpr auto result = test();
    static_assert(result.index == 1, "");
    static_assert(result.value == 42l, "");
  }
  {
    struct
    {
      __host__ __device__ constexpr Result<long> operator()() const
      {
        using V = cuda::std::variant<int, TMoveAssign, unsigned>;
        V v(cuda::std::in_place_type<unsigned>, 43u);
        V v2(cuda::std::in_place_type<TMoveAssign>, 42);
        v = cuda::std::move(v2);
        return {v.index(), cuda::std::get<1>(v).value};
      }
    } test;
    constexpr auto result = test();
    static_assert(result.index == 1, "");
    static_assert(result.value == 42, "");
  }
}

template <size_t NewIdx, class ValueType>
__host__ __device__ constexpr bool
test_constexpr_assign_imp(cuda::std::variant<long, void*, int>&& v, ValueType&& new_value)
{
  cuda::std::variant<long, void*, int> v2(cuda::std::forward<ValueType>(new_value));
  const auto cp = v2;
  v             = cuda::std::move(v2);
  return v.index() == NewIdx && cuda::std::get<NewIdx>(v) == cuda::std::get<NewIdx>(cp);
}

__host__ __device__ void test_constexpr_move_assignment()
{
  // Make sure we properly propagate triviality, which implies constexpr-ness (see P0602R4).
  using V = cuda::std::variant<long, void*, int>;
  static_assert(cuda::std::is_trivially_copyable<V>::value, "");
  static_assert(cuda::std::is_trivially_move_assignable<V>::value, "");
  static_assert(test_constexpr_assign_imp<0>(V(42l), 101l), "");
  static_assert(test_constexpr_assign_imp<0>(V(nullptr), 101l), "");
  static_assert(test_constexpr_assign_imp<1>(V(42l), nullptr), "");
  static_assert(test_constexpr_assign_imp<2>(V(42l), 101), "");
}

int main(int, char**)
{
#ifndef TEST_HAS_NO_EXCEPTIONS
  NV_IF_TARGET(NV_IS_HOST, (test_move_assignment_empty_empty();))
  NV_IF_TARGET(NV_IS_HOST, (test_move_assignment_non_empty_empty();))
  NV_IF_TARGET(NV_IS_HOST, (test_move_assignment_empty_non_empty();))
#endif // !TEST_HAS_NO_EXCEPTIONS

  test_move_assignment_same_index();
  test_move_assignment_different_index();
  test_move_assignment_sfinae();
  test_move_assignment_noexcept();
  test_constexpr_move_assignment();

  return 0;
}
