//===----------------------------------------------------------------------===//
//
// 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++98, c++03, c++11, c++14
// <optional>

// template <class T, class U> constexpr bool operator!=(const optional<T>& x, const U& v);
// template <class T, class U> constexpr bool operator!=(const U& v, const optional<T>& x);

#include <optional>

using std::optional;

struct X {
  int i_;

  constexpr X(int i) : i_(i) {}
};

constexpr bool operator!=(const X& lhs, const X& rhs) {
  return lhs.i_ != rhs.i_;
}

int main(int, char**) {
  {
    typedef X T;
    typedef optional<T> O;

    constexpr T val(2);
    constexpr O o1;      // disengaged
    constexpr O o2{1};   // engaged
    constexpr O o3{val}; // engaged

    static_assert((o1 != T(1)), "");
    static_assert(!(o2 != T(1)), "");
    static_assert((o3 != T(1)), "");
    static_assert(!(o3 != T(2)), "");
    static_assert(!(o3 != val), "");

    static_assert((T(1) != o1), "");
    static_assert(!(T(1) != o2), "");
    static_assert((T(1) != o3), "");
    static_assert(!(T(2) != o3), "");
    static_assert(!(val != o3), "");
  }
  {
    using O = optional<int>;
    constexpr O o1(42);
    static_assert(o1 != 101l, "");
    static_assert(!(42l != o1), "");
  }
  {
    using O = optional<const int>;
    constexpr O o1(42);
    static_assert(o1 != 101, "");
    static_assert(!(42 != o1), "");
  }

  return 0;
}