#include <array>
#include <cassert>
#include <cstddef>
#include <iostream>

struct Trace {
    std::array<int, 5> values{};
    std::size_t used = 0;
    void add(int value) noexcept {
        assert(used < values.size());
        values[used++] = value;
    }
};

class Base {
protected:
    Trace& trace;
    void sample() { trace.add(kind()); }
public:
    explicit Base(Trace& t) : trace(t) { sample(); }
    virtual ~Base() { sample(); }
    virtual int kind() const noexcept { return 1; }
};

class Derived final : public Base {
public:
    explicit Derived(Trace& t) : Base(t) { sample(); }
    ~Derived() override { sample(); }
    int kind() const noexcept override { return 2; }
};

int main() {
    Trace trace;
    {
        Derived object(trace);
        const Base& view = object;
        trace.add(view.kind());
    }
    const std::array<int, 5> expected{{1, 2, 2, 2, 1}};
    assert(trace.used == expected.size());
    assert(trace.values == expected);
    for (std::size_t i = 0; i < trace.used; ++i) {
        if (i != 0) std::cout << ' ';
        std::cout << trace.values[i];
    }
    std::cout << '\n';
}