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 // weak_ptr(const weak_ptr& r);
15 // weak_ptr(weak_ptr &&r)
16 
17 #include <memory>
18 #include <type_traits>
19 #include <cassert>
20 
21 struct B
22 {
23     static int count;
24 
BB25     B() {++count;}
BB26     B(const B&) {++count;}
~BB27     virtual ~B() {--count;}
28 };
29 
30 int B::count = 0;
31 
32 struct A
33     : public B
34 {
35     static int count;
36 
AA37     A() {++count;}
AA38     A(const A&) {++count;}
~AA39     ~A() {--count;}
40 };
41 
42 int A::count = 0;
43 
44 struct C
45 {
46     static int count;
47 
CC48     C() {++count;}
CC49     C(const C&) {++count;}
~CC50     virtual ~C() {--count;}
51 };
52 
53 int C::count = 0;
54 
55 template <class T>
source(std::shared_ptr<T> p)56 std::weak_ptr<T> source (std::shared_ptr<T> p) { return std::weak_ptr<T>(p); }
57 
58 template <class T>
sink(std::weak_ptr<T> &&)59 void sink (std::weak_ptr<T> &&) {}
60 
main()61 int main()
62 {
63     {
64         const std::shared_ptr<A> ps(new A);
65         const std::weak_ptr<A> pA(ps);
66         assert(pA.use_count() == 1);
67         assert(B::count == 1);
68         assert(A::count == 1);
69         {
70             std::weak_ptr<A> pB(pA);
71             assert(B::count == 1);
72             assert(A::count == 1);
73             assert(pB.use_count() == 1);
74             assert(pA.use_count() == 1);
75         }
76         assert(pA.use_count() == 1);
77         assert(B::count == 1);
78         assert(A::count == 1);
79     }
80     assert(B::count == 0);
81     assert(A::count == 0);
82     {
83         std::weak_ptr<A> pA;
84         assert(pA.use_count() == 0);
85         assert(B::count == 0);
86         assert(A::count == 0);
87         {
88             std::weak_ptr<A> pB(pA);
89             assert(B::count == 0);
90             assert(A::count == 0);
91             assert(pB.use_count() == 0);
92             assert(pA.use_count() == 0);
93         }
94         assert(pA.use_count() == 0);
95         assert(B::count == 0);
96         assert(A::count == 0);
97     }
98     assert(B::count == 0);
99     assert(A::count == 0);
100 
101     {
102         std::shared_ptr<A> ps(new A);
103         std::weak_ptr<A> pA = source(ps);
104         assert(pA.use_count() == 1);
105         assert(A::count == 1);
106         sink(std::move(pA)); // kill off the weak pointer
107     }
108     assert(B::count == 0);
109     assert(A::count == 0);
110 }
111