src/third_party/llvm-project/libcxx/test/std/containers/sequences/forwardlist/forwardlist.modifiers/emplace_front.pass.cpp

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

// <forward_list>

// template <class... Args> reference emplace_front(Args&&... args);
// return type is 'reference' in C++17; 'void' before

#include <forward_list>
#include <cassert>

#include "test_macros.h"

#include "../../../Emplaceable.h"
#include "min_allocator.h"

int main()
{
    {
        typedef Emplaceable T;
        typedef std::forward_list<T> C;
        C c;
#if TEST_STD_VER > 14
        T& r1 = c.emplace_front();
        assert(c.front() == Emplaceable());
        assert(&r1 == &c.front());
        assert(distance(c.begin(), c.end()) == 1);
        T& r2 = c.emplace_front(1, 2.5);
        assert(c.front() == Emplaceable(1, 2.5));
        assert(&r2 == &c.front());
#else
        c.emplace_front();
        assert(c.front() == Emplaceable());
        assert(distance(c.begin(), c.end()) == 1);
        c.emplace_front(1, 2.5);
        assert(c.front() == Emplaceable(1, 2.5));
#endif
        assert(*next(c.begin()) == Emplaceable());
        assert(distance(c.begin(), c.end()) == 2);
    }
    {
        typedef Emplaceable T;
        typedef std::forward_list<T, min_allocator<T>> C;
        C c;
#if TEST_STD_VER > 14
        T& r1 = c.emplace_front();
        assert(c.front() == Emplaceable());
        assert(&r1 == &c.front());
        assert(distance(c.begin(), c.end()) == 1);
        T& r2 = c.emplace_front(1, 2.5);
        assert(c.front() == Emplaceable(1, 2.5));
        assert(&r2 == &c.front());
#else
        c.emplace_front();
        assert(c.front() == Emplaceable());
        assert(distance(c.begin(), c.end()) == 1);
        c.emplace_front(1, 2.5);
        assert(c.front() == Emplaceable(1, 2.5));
#endif
        assert(*next(c.begin()) == Emplaceable());
        assert(distance(c.begin(), c.end()) == 2);
    }
}