//===----------------------------------------------------------------------===//
//
//                     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
// <optional>

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

#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() {
  {
    typedef optional<X> O;

    constexpr O o1;    // disengaged
    constexpr O o2;    // disengaged
    constexpr O o3{1}; // engaged
    constexpr O o4{2}; // engaged
    constexpr O o5{1}; // engaged

    static_assert((o1 <= o1), "");
    static_assert((o1 <= o2), "");
    static_assert((o1 <= o3), "");
    static_assert((o1 <= o4), "");
    static_assert((o1 <= o5), "");

    static_assert((o2 <= o1), "");
    static_assert((o2 <= o2), "");
    static_assert((o2 <= o3), "");
    static_assert((o2 <= o4), "");
    static_assert((o2 <= o5), "");

    static_assert(!(o3 <= o1), "");
    static_assert(!(o3 <= o2), "");
    static_assert((o3 <= o3), "");
    static_assert((o3 <= o4), "");
    static_assert((o3 <= o5), "");

    static_assert(!(o4 <= o1), "");
    static_assert(!(o4 <= o2), "");
    static_assert(!(o4 <= o3), "");
    static_assert((o4 <= o4), "");
    static_assert(!(o4 <= o5), "");

    static_assert(!(o5 <= o1), "");
    static_assert(!(o5 <= o2), "");
    static_assert((o5 <= o3), "");
    static_assert((o5 <= o4), "");
    static_assert((o5 <= o5), "");
  }
  {
    using O1 = optional<int>;
    using O2 = optional<long>;
    constexpr O1 o1(42);
    static_assert(o1 <= O2(42), "");
    static_assert(!(O2(101) <= o1), "");
  }
  {
    using O1 = optional<int>;
    using O2 = optional<const int>;
    constexpr O1 o1(42);
    static_assert(o1 <= O2(42), "");
    static_assert(!(O2(101) <= o1), "");
  }
}