weak_ptr_Y.pass.cpp [plain text]
#include <memory>
#include <type_traits>
#include <cassert>
struct B
{
static int count;
B() {++count;}
B(const B&) {++count;}
virtual ~B() {--count;}
};
int B::count = 0;
struct A
: public B
{
static int count;
A() {++count;}
A(const A&) {++count;}
~A() {--count;}
};
int A::count = 0;
struct C
{
static int count;
C() {++count;}
C(const C&) {++count;}
virtual ~C() {--count;}
};
int C::count = 0;
int main()
{
static_assert(( std::is_convertible<std::weak_ptr<A>, std::weak_ptr<B> >::value), "");
static_assert((!std::is_convertible<std::weak_ptr<B>, std::weak_ptr<A> >::value), "");
static_assert((!std::is_convertible<std::weak_ptr<A>, std::weak_ptr<C> >::value), "");
{
const std::weak_ptr<A> pA(std::shared_ptr<A>(new A));
assert(pA.use_count() == 0);
assert(B::count == 0);
assert(A::count == 0);
{
std::weak_ptr<B> pB(pA);
assert(B::count == 0);
assert(A::count == 0);
assert(pB.use_count() == 0);
assert(pA.use_count() == 0);
}
assert(pA.use_count() == 0);
assert(B::count == 0);
assert(A::count == 0);
}
assert(B::count == 0);
assert(A::count == 0);
{
std::weak_ptr<A> pA;
assert(pA.use_count() == 0);
assert(B::count == 0);
assert(A::count == 0);
{
std::weak_ptr<B> pB(pA);
assert(B::count == 0);
assert(A::count == 0);
assert(pB.use_count() == 0);
assert(pA.use_count() == 0);
}
assert(pA.use_count() == 0);
assert(B::count == 0);
assert(A::count == 0);
}
assert(B::count == 0);
assert(A::count == 0);
}