1 //===----------------------------------------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
14 // template<class Y> weak_ptr(const weak_ptr<Y>& r);
17 #include <type_traits>
25 B(const B&) {++count;}
26 virtual ~B() {--count;}
37 A(const A&) {++count;}
48 C(const C&) {++count;}
49 virtual ~C() {--count;}
56 static_assert(( std::is_convertible<std::weak_ptr<A>, std::weak_ptr<B> >::value), "");
57 static_assert((!std::is_convertible<std::weak_ptr<B>, std::weak_ptr<A> >::value), "");
58 static_assert((!std::is_convertible<std::weak_ptr<A>, std::weak_ptr<C> >::value), "");
60 const std::weak_ptr<A> pA(std::shared_ptr<A>(new A));
61 assert(pA.use_count() == 0);
62 assert(B::count == 0);
63 assert(A::count == 0);
65 std::weak_ptr<B> pB(pA);
66 assert(B::count == 0);
67 assert(A::count == 0);
68 assert(pB.use_count() == 0);
69 assert(pA.use_count() == 0);
71 assert(pA.use_count() == 0);
72 assert(B::count == 0);
73 assert(A::count == 0);
75 assert(B::count == 0);
76 assert(A::count == 0);
79 assert(pA.use_count() == 0);
80 assert(B::count == 0);
81 assert(A::count == 0);
83 std::weak_ptr<B> pB(pA);
84 assert(B::count == 0);
85 assert(A::count == 0);
86 assert(pB.use_count() == 0);
87 assert(pA.use_count() == 0);
89 assert(pA.use_count() == 0);
90 assert(B::count == 0);
91 assert(A::count == 0);
93 assert(B::count == 0);
94 assert(A::count == 0);