//===----------------------------------------------------------------------===//
//
// 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, c++11, c++14
// <optional>

// constexpr optional(const optional<T>& rhs);

#include <cassert>
#include <optional>
#include <type_traits>

#include "test_macros.h"
#include "archetypes.h"

using std::optional;

template <class T, class... InitArgs>
void test(InitArgs&&... args) {
  const optional<T> rhs(std::forward<InitArgs>(args)...);
  bool rhs_engaged = static_cast<bool>(rhs);
  optional<T> lhs  = rhs;
  assert(static_cast<bool>(lhs) == rhs_engaged);
  if (rhs_engaged)
    assert(*lhs == *rhs);
}

template <class T, class... InitArgs>
constexpr bool constexpr_test(InitArgs&&... args) {
  static_assert(std::is_trivially_copy_constructible_v<T>, ""); // requirement
  const optional<T> rhs(std::forward<InitArgs>(args)...);
  optional<T> lhs = rhs;
  return (lhs.has_value() == rhs.has_value()) && (lhs.has_value() ? *lhs == *rhs : true);
}

void test_throwing_ctor() {
#ifndef TEST_HAS_NO_EXCEPTIONS
  struct Z {
    Z() : count(0) {}
    Z(Z const& o) : count(o.count + 1) {
      if (count == 2)
        throw 6;
    }
    int count;
  };
  const Z z;
  const optional<Z> rhs(z);
  try {
    optional<Z> lhs(rhs);
    assert(false);
  } catch (int i) {
    assert(i == 6);
  }
#endif
}

template <class T, class... InitArgs>
void test_ref(InitArgs&&... args) {
  const optional<T> rhs(std::forward<InitArgs>(args)...);
  bool rhs_engaged = static_cast<bool>(rhs);
  optional<T> lhs  = rhs;
  assert(static_cast<bool>(lhs) == rhs_engaged);
  if (rhs_engaged)
    assert(&(*lhs) == &(*rhs));
}

#if TEST_STD_VER >= 26
void test_reference_extension() {
  using T = TestTypes::TestType;
  T::reset();
  {
    T t;
    T::reset_constructors();
    test_ref<T&>();
    test_ref<T&>(t);
    assert(T::alive == 1);
    assert(T::constructed == 0);
    assert(T::assigned == 0);
    assert(T::destroyed == 0);
  }
  assert(T::destroyed == 1);
  assert(T::alive == 0);
  {
    T t;
    const T& ct = t;
    T::reset_constructors();
    test_ref<T const&>();
    test_ref<T const&>(t);
    test_ref<T const&>(ct);
    assert(T::alive == 1);
    assert(T::constructed == 0);
    assert(T::assigned == 0);
    assert(T::destroyed == 0);
  }
  assert(T::alive == 0);
  assert(T::destroyed == 1);

#  if 0 // optional<T&&> is not permitted.
  {
    static_assert(!std::is_copy_constructible<std::optional<T&&>>::value, "");
    static_assert(!std::is_copy_constructible<std::optional<T const&&>>::value, "");
  }
#  endif
}
#endif

int main(int, char**) {
  test<int>();
  test<int>(3);
  static_assert(constexpr_test<int>(), "");
  static_assert(constexpr_test<int>(3), "");

  {
    const optional<const int> o(42);
    optional<const int> o2(o);
    assert(*o2 == 42);
  }
  {
    using T = TestTypes::TestType;
    T::reset();
    const optional<T> rhs;
    assert(T::alive == 0);
    const optional<T> lhs(rhs);
    assert(lhs.has_value() == false);
    assert(T::alive == 0);
  }
  TestTypes::TestType::reset();
  {
    using T = TestTypes::TestType;
    T::reset();
    const optional<T> rhs(42);
    assert(T::alive == 1);
    assert(T::value_constructed == 1);
    assert(T::copy_constructed == 0);
    const optional<T> lhs(rhs);
    assert(lhs.has_value());
    assert(T::copy_constructed == 1);
    assert(T::alive == 2);
  }
  TestTypes::TestType::reset();
  {
    using namespace ConstexprTestTypes;
    test<TestType>();
    test<TestType>(42);
  }
  {
    using namespace TrivialTestTypes;
    test<TestType>();
    test<TestType>(42);
  }
  {
    test_throwing_ctor();
  }
#if TEST_STD_VER >= 26
  {
    test_reference_extension();
  }
#endif
  {
    constexpr std::optional<int> o1{4};
    constexpr std::optional<int> o2 = o1;
    static_assert(*o2 == 4, "");
  }

  // LWG3836 https://wg21.link/LWG3836
  // std::optional<bool> conversion constructor optional(const optional<U>&)
  // should take precedence over optional(U&&) with operator bool
  {
    std::optional<bool> o1(false);
    std::optional<bool> o2(o1);
    assert(!o2.value());
  }

  return 0;
}