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 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
59 template <class T>
sink(std::weak_ptr<T> &&)60 void sink (std::weak_ptr<T> &&) {}
61 #endif
62 
main()63 int main()
64 {
65     {
66         const std::shared_ptr<A> ps(new A);
67         const std::weak_ptr<A> pA(ps);
68         assert(pA.use_count() == 1);
69         assert(B::count == 1);
70         assert(A::count == 1);
71         {
72             std::weak_ptr<A> pB(pA);
73             assert(B::count == 1);
74             assert(A::count == 1);
75             assert(pB.use_count() == 1);
76             assert(pA.use_count() == 1);
77         }
78         assert(pA.use_count() == 1);
79         assert(B::count == 1);
80         assert(A::count == 1);
81     }
82     assert(B::count == 0);
83     assert(A::count == 0);
84     {
85         std::weak_ptr<A> pA;
86         assert(pA.use_count() == 0);
87         assert(B::count == 0);
88         assert(A::count == 0);
89         {
90             std::weak_ptr<A> pB(pA);
91             assert(B::count == 0);
92             assert(A::count == 0);
93             assert(pB.use_count() == 0);
94             assert(pA.use_count() == 0);
95         }
96         assert(pA.use_count() == 0);
97         assert(B::count == 0);
98         assert(A::count == 0);
99     }
100     assert(B::count == 0);
101     assert(A::count == 0);
102 
103 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
104     {
105         std::shared_ptr<A> ps(new A);
106         std::weak_ptr<A> pA = source(ps);
107         assert(pA.use_count() == 1);
108         assert(A::count == 1);
109         sink(std::move(pA)); // kill off the weak pointer
110     }
111     assert(B::count == 0);
112     assert(A::count == 0);
113 #endif
114 }
115