std::weak_ptr<T>::~weak_ptr

#include <iostream>
#include <memory>
#include <variant>
 
class Node
{
 char id;
 std::variant <std::weak_ptr <Node>, std::shared_ptr <Node>> ptr;
public:
 Node(char id) : id{id} {}
 ~Node() { std::cout << " '" << id << "' reclaimed\n"; }
 /*...*/
 void assign(std::weak_ptr <Node> p) { ptr = p; }
 void assign(std::shared_ptr <Node> p) { ptr = p; }
};
 
enum class shared { all, some };
 
void test_cyclic_graph(const shared x)
{
 auto A = std::make_shared <Node>('A');
 auto B = std::make_shared <Node>('B');
 auto C = std::make_shared <Node>('C');
 
 A->assign(B);
 B->assign(C);
 
 if (shared::all == x)
 {
 C->assign(A);
 std::cout << "All links are shared pointers";
 }
 else
 {
 C->assign(std::weak_ptr <Node>(A));
 std::cout << "One link is a weak_ptr";
 }
 /*...*/
 std::cout << "\nLeaving...\n";
}
 
int main()
{
 test_cyclic_graph(shared::some);
 test_cyclic_graph(shared::all); // produces a memory leak
}

One link is a weak_ptr
Leaving...
 'A' reclaimed
 'B' reclaimed
 'C' reclaimed
All links are shared pointers
Leaving...