Method pop

tests/relacy/relacy/example/stack/stack.cpp:29–50

    }

    int pop()
    {
        node* n = head_.load(rl::memory_order_relaxed);
        for (;;)
        {
            if (0 == n)
                break;
            node* next = n->next_.load(rl::memory_order_relaxed);
            if (head_.compare_exchange_weak(n, next, rl::memory_order_acquire))
                break;
        }
        if (n)
        {
            int data = n->data_($);
            delete n;
            return data;
        }
        else
        {
            return 0;
        }
    }

private:
    struct node