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

// <memory>

// shared_ptr

// template<class T, class U> shared_ptr<T> dynamic_pointer_cast(const shared_ptr<U>& r);

#include <memory>
#include <type_traits>
#include <cassert>

struct B
{
    static int count;

    B() {++count;}
    B(const B&) {++count;}
    virtual ~B() {--count;}
};

int B::count = 0;

struct A
    : public B
{
    static int count;

    A() {++count;}
    A(const A&) {++count;}
    ~A() {--count;}
};

int A::count = 0;

int main(int, char**)
{
    {
        const std::shared_ptr<B> pB(new A);
        std::shared_ptr<A> pA = std::dynamic_pointer_cast<A>(pB);
        assert(pA.get() == pB.get());
        assert(!pB.owner_before(pA) && !pA.owner_before(pB));
    }
    {
        const std::shared_ptr<B> pB(new B);
        std::shared_ptr<A> pA = std::dynamic_pointer_cast<A>(pB);
        assert(pA.get() == 0);
        assert(pA.use_count() == 0);
    }

  return 0;
}