test/std/containers/sequences/deque/deque.special/swap_noexcept.pass.cpp

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

// <deque>

// void swap(deque& c)
//     noexcept(!allocator_type::propagate_on_container_swap::value ||
//              __is_nothrow_swappable<allocator_type>::value);
//
//  In C++17, the standard says that swap shall have:
//     noexcept(allocator_traits<Allocator>::is_always_equal::value);

// This tests a conforming extension

#include <deque>
#include <utility>
#include <cassert>

#include "test_macros.h"
#include "MoveOnly.h"
#include "test_allocator.h"

template <class T>
struct some_alloc
{
    typedef T value_type;

    some_alloc() {}
    some_alloc(const some_alloc&);
    void deallocate(void*, unsigned) {}

    typedef std::true_type propagate_on_container_swap;
};

template <class T>
struct some_alloc2
{
    typedef T value_type;

    some_alloc2() {}
    some_alloc2(const some_alloc2&);
    void deallocate(void*, unsigned) {}

    typedef std::false_type propagate_on_container_swap;
    typedef std::true_type is_always_equal;
};

int main(int, char**)
{
    {
        typedef std::deque<MoveOnly> C;
        static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
    }
#if defined(_LIBCPP_VERSION)
    {
        typedef std::deque<MoveOnly, test_allocator<MoveOnly>> C;
        static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
    }
    {
        typedef std::deque<MoveOnly, other_allocator<MoveOnly>> C;
        static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
    }
#endif // _LIBCPP_VERSION
    {
        typedef std::deque<MoveOnly, some_alloc<MoveOnly>> C;
#if TEST_STD_VER >= 14
    //  In C++14, if POCS is set, swapping the allocator is required not to throw
        static_assert( noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
#else
        static_assert(!noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
#endif
    }
#if TEST_STD_VER >= 14
    {
        typedef std::deque<MoveOnly, some_alloc2<MoveOnly>> C;
    //  if the allocators are always equal, then the swap can be noexcept
        static_assert( noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
    }
#endif


  return 0;
}