//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

// <array>

// template <class T, size_t N> void swap(array<T,N>& x, array<T,N>& y);

#include <array>
#include <cassert>
#include <utility>

#include "test_macros.h"

struct NonSwappable {
  TEST_CONSTEXPR NonSwappable() {}

private:
  NonSwappable(NonSwappable const&);
  NonSwappable& operator=(NonSwappable const&);
};

template <class Tp>
decltype(swap(std::declval<Tp>(), std::declval<Tp>())) can_swap_imp(int);

template <class Tp>
std::false_type can_swap_imp(...);

template <class Tp>
struct can_swap : std::is_same<decltype(can_swap_imp<Tp>(0)), void> {};

TEST_CONSTEXPR_CXX20 bool tests() {
  {
    typedef double T;
    typedef std::array<T, 3> C;
    C c1 = {1, 2, 3.5};
    C c2 = {4, 5, 6.5};
    swap(c1, c2);
    assert(c1.size() == 3);
    assert(c1[0] == 4);
    assert(c1[1] == 5);
    assert(c1[2] == 6.5);
    assert(c2.size() == 3);
    assert(c2[0] == 1);
    assert(c2[1] == 2);
    assert(c2[2] == 3.5);
  }
  {
    typedef double T;
    typedef std::array<T, 0> C;
    C c1 = {};
    C c2 = {};
    swap(c1, c2);
    assert(c1.size() == 0);
    assert(c2.size() == 0);
  }
  {
    typedef NonSwappable T;
    typedef std::array<T, 0> C0;
    static_assert(can_swap<C0&>::value, "");
    C0 l = {};
    C0 r = {};
    swap(l, r);
#if TEST_STD_VER >= 11
    static_assert(noexcept(swap(l, r)), "");
#endif
  }
#if TEST_STD_VER >= 11
  {
    // NonSwappable is still considered swappable in C++03 because there
    // is no access control SFINAE.
    typedef NonSwappable T;
    typedef std::array<T, 42> C1;
    static_assert(!can_swap<C1&>::value, "");
  }
#endif

  return true;
}

int main(int, char**) {
  tests();
#if TEST_STD_VER >= 20
  static_assert(tests(), "");
#endif
  return 0;
}
