text: //===----------------------------------------------------------------------===//
  //
  //                     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.
  //
  //===----------------------------------------------------------------------===//
  
  // XFAIL: libcpp-no-exceptions
  // <optional>
  
  // void swap(optional&)
  //     noexcept(is_nothrow_move_constructible<T>::value &&
  //              noexcept(swap(declval<T&>(), declval<T&>())));
  
  #include <experimental/optional>
  #include <type_traits>
  #include <cassert>
  
  #if _LIBCPP_STD_VER > 11
  
  using std::experimental::optional;
  
  class X
  {
      int i_;
  public:
      static unsigned dtor_called;
      X(int i) : i_(i) {}
      X(X&& x) = default;
      X& operator=(X&&) = default;
      ~X() {++dtor_called;}
  
      friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
  };
  
  unsigned X::dtor_called = 0;
  
  class Y
  {
      int i_;
  public:
      static unsigned dtor_called;
      Y(int i) : i_(i) {}
      Y(Y&&) = default;
      ~Y() {++dtor_called;}
  
      friend constexpr bool operator==(const Y& x, const Y& y) {return x.i_ == y.i_;}
      friend void swap(Y& x, Y& y) {std::swap(x.i_, y.i_);}
  };
  
  unsigned Y::dtor_called = 0;
  
  class Z
  {
      int i_;
  public:
      Z(int i) : i_(i) {}
      Z(Z&&) {throw 7;}
  
      friend constexpr bool operator==(const Z& x, const Z& y) {return x.i_ == y.i_;}
      friend void swap(Z& x, Z& y) {throw 6;}
  };
  
  
  #endif  // _LIBCPP_STD_VER > 11
  
  int main()
  {
  #if _LIBCPP_STD_VER > 11
      {
          optional<int> opt1;
          optional<int> opt2;
          static_assert(noexcept(opt1.swap(opt2)) == true, "");
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == false);
          opt1.swap(opt2);
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == false);
      }
      {
          optional<int> opt1(1);
          optional<int> opt2;
          static_assert(noexcept(opt1.swap(opt2)) == true, "");
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 1);
          assert(static_cast<bool>(opt2) == false);
          opt1.swap(opt2);
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 1);
      }
      {
          optional<int> opt1;
          optional<int> opt2(2);
          static_assert(noexcept(opt1.swap(opt2)) == true, "");
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 2);
          opt1.swap(opt2);
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 2);
          assert(static_cast<bool>(opt2) == false);
      }
      {
          optional<int> opt1(1);
          optional<int> opt2(2);
          static_assert(noexcept(opt1.swap(opt2)) == true, "");
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 1);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 2);
          opt1.swap(opt2);
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 2);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 1);
      }
      {
          optional<X> opt1;
          optional<X> opt2;
          static_assert(noexcept(opt1.swap(opt2)) == true, "");
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == false);
          opt1.swap(opt2);
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == false);
          assert(X::dtor_called == 0);
      }
      {
          optional<X> opt1(1);
          optional<X> opt2;
          static_assert(noexcept(opt1.swap(opt2)) == true, "");
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 1);
          assert(static_cast<bool>(opt2) == false);
          X::dtor_called = 0;
          opt1.swap(opt2);
          assert(X::dtor_called == 1);
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 1);
      }
      {
          optional<X> opt1;
          optional<X> opt2(2);
          static_assert(noexcept(opt1.swap(opt2)) == true, "");
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 2);
          X::dtor_called = 0;
          opt1.swap(opt2);
          assert(X::dtor_called == 1);
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 2);
          assert(static_cast<bool>(opt2) == false);
      }
      {
          optional<X> opt1(1);
          optional<X> opt2(2);
          static_assert(noexcept(opt1.swap(opt2)) == true, "");
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 1);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 2);
          X::dtor_called = 0;
          opt1.swap(opt2);
          assert(X::dtor_called == 1);  // from inside std::swap
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 2);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 1);
      }
      {
          optional<Y> opt1;
          optional<Y> opt2;
          static_assert(noexcept(opt1.swap(opt2)) == false, "");
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == false);
          opt1.swap(opt2);
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == false);
          assert(Y::dtor_called == 0);
      }
      {
          optional<Y> opt1(1);
          optional<Y> opt2;
          static_assert(noexcept(opt1.swap(opt2)) == false, "");
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 1);
          assert(static_cast<bool>(opt2) == false);
          Y::dtor_called = 0;
          opt1.swap(opt2);
          assert(Y::dtor_called == 1);
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 1);
      }
      {
          optional<Y> opt1;
          optional<Y> opt2(2);
          static_assert(noexcept(opt1.swap(opt2)) == false, "");
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 2);
          Y::dtor_called = 0;
          opt1.swap(opt2);
          assert(Y::dtor_called == 1);
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 2);
          assert(static_cast<bool>(opt2) == false);
      }
      {
          optional<Y> opt1(1);
          optional<Y> opt2(2);
          static_assert(noexcept(opt1.swap(opt2)) == false, "");
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 1);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 2);
          Y::dtor_called = 0;
          opt1.swap(opt2);
          assert(Y::dtor_called == 0);
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 2);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 1);
      }
      {
          optional<Z> opt1;
          optional<Z> opt2;
          static_assert(noexcept(opt1.swap(opt2)) == false, "");
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == false);
          opt1.swap(opt2);
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == false);
      }
      {
          optional<Z> opt1;
          opt1.emplace(1);
          optional<Z> opt2;
          static_assert(noexcept(opt1.swap(opt2)) == false, "");
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 1);
          assert(static_cast<bool>(opt2) == false);
          try
          {
              opt1.swap(opt2);
              assert(false);
          }
          catch (int i)
          {
              assert(i == 7);
          }
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 1);
          assert(static_cast<bool>(opt2) == false);
      }
      {
          optional<Z> opt1;
          optional<Z> opt2;
          opt2.emplace(2);
          static_assert(noexcept(opt1.swap(opt2)) == false, "");
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 2);
          try
          {
              opt1.swap(opt2);
              assert(false);
          }
          catch (int i)
          {
              assert(i == 7);
          }
          assert(static_cast<bool>(opt1) == false);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 2);
      }
      {
          optional<Z> opt1;
          opt1.emplace(1);
          optional<Z> opt2;
          opt2.emplace(2);
          static_assert(noexcept(opt1.swap(opt2)) == false, "");
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 1);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 2);
          try
          {
              opt1.swap(opt2);
              assert(false);
          }
          catch (int i)
          {
              assert(i == 6);
          }
          assert(static_cast<bool>(opt1) == true);
          assert(*opt1 == 1);
          assert(static_cast<bool>(opt2) == true);
          assert(*opt2 == 2);
      }
  #endif  // _LIBCPP_STD_VER > 11
  }
  