test/std/utilities/memory/util.smartptr/util.smartptr.weak/util.smartptr.weak.obs/lock.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
//
//===----------------------------------------------------------------------===//

// <memory>

// weak_ptr

// shared_ptr<T> lock() const;

#include <memory>
#include <cassert>

struct A
{
    static int count;

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

int A::count = 0;

int main(int, char**)
{
    {
        std::weak_ptr<A> wp;
        std::shared_ptr<A> sp = wp.lock();
        assert(sp.use_count() == 0);
        assert(sp.get() == 0);
        assert(A::count == 0);
    }
    {
        std::shared_ptr<A> sp0(new A);
        std::weak_ptr<A> wp(sp0);
        std::shared_ptr<A> sp = wp.lock();
        assert(sp.use_count() == 2);
        assert(sp.get() == sp0.get());
        assert(A::count == 1);
    }
    assert(A::count == 0);
    {
        std::shared_ptr<A> sp0(new A);
        std::weak_ptr<A> wp(sp0);
        sp0.reset();
        std::shared_ptr<A> sp = wp.lock();
        assert(sp.use_count() == 0);
        assert(sp.get() == 0);
        assert(A::count == 0);
    }
    assert(A::count == 0);

  return 0;
}