1//===----------------------------------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is dual licensed under the MIT and the University of Illinois Open
6// Source Licenses. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10// <memory>
11
12// weak_ptr
13
14// template<class Y> weak_ptr(const weak_ptr<Y>& r);
15// template<class Y> weak_ptr(weak_ptr<Y> &&r);
16
17#include <memory>
18#include <type_traits>
19#include <cassert>
20
21struct B
22{
23    static int count;
24
25    B() {++count;}
26    B(const B&) {++count;}
27    virtual ~B() {--count;}
28};
29
30int B::count = 0;
31
32struct A
33    : public B
34{
35    static int count;
36
37    A() {++count;}
38    A(const A&) {++count;}
39    ~A() {--count;}
40};
41
42int A::count = 0;
43
44struct C
45{
46    static int count;
47
48    C() {++count;}
49    C(const C&) {++count;}
50    virtual ~C() {--count;}
51};
52
53int C::count = 0;
54
55template <class T>
56std::weak_ptr<T> source (std::shared_ptr<T> p) { return std::weak_ptr<T>(p); }
57
58int main()
59{
60    static_assert(( std::is_convertible<std::weak_ptr<A>, std::weak_ptr<B> >::value), "");
61    static_assert((!std::is_convertible<std::weak_ptr<B>, std::weak_ptr<A> >::value), "");
62    static_assert((!std::is_convertible<std::weak_ptr<A>, std::weak_ptr<C> >::value), "");
63    {
64        const std::weak_ptr<A> pA(std::shared_ptr<A>(new A));
65        assert(pA.use_count() == 0);
66        assert(B::count == 0);
67        assert(A::count == 0);
68        {
69            std::weak_ptr<B> pB(pA);
70            assert(B::count == 0);
71            assert(A::count == 0);
72            assert(pB.use_count() == 0);
73            assert(pA.use_count() == 0);
74        }
75        assert(pA.use_count() == 0);
76        assert(B::count == 0);
77        assert(A::count == 0);
78    }
79    assert(B::count == 0);
80    assert(A::count == 0);
81    {
82        std::weak_ptr<A> pA;
83        assert(pA.use_count() == 0);
84        assert(B::count == 0);
85        assert(A::count == 0);
86        {
87            std::weak_ptr<B> pB(pA);
88            assert(B::count == 0);
89            assert(A::count == 0);
90            assert(pB.use_count() == 0);
91            assert(pA.use_count() == 0);
92        }
93        assert(pA.use_count() == 0);
94        assert(B::count == 0);
95        assert(A::count == 0);
96    }
97    assert(B::count == 0);
98    assert(A::count == 0);
99
100    {
101        std::shared_ptr<A> ps(new A);
102        std::weak_ptr<A> pA = source(ps);
103        std::weak_ptr<B> pB(std::move(pA));
104        assert(pB.use_count() == 1);
105    }
106    assert(B::count == 0);
107    assert(A::count == 0);
108}
109