import std;

constexpr auto make_checker() {
    return [](int x) consteval {
        return x % 3 == 0 || x % 5 == 0;
    };
}

int main() {
    auto checker = make_checker();

    std::vector numbers{1, 3, 5, 9, 10, 14, 15};

    auto filtered = numbers | std::views::filter([&](int x) {
        if (std::is_constant_evaluated()) {
            std::print("constexpr\n");
        }
        return checker(x);
    });

    std::print("Filtered numbers: ");
    for (int x : filtered) {
        std::print("{} ", x);
    }

    std::println("");
} 

#include <iostream>
using namespace std;

class Base {
public:
    Base() {
        cout << "Base constructor: ";
        call();
    }
    virtual void call() { cout << "Base::call\n"; }
};

class Derived : public Base {
    int x = init();

    int init() {
        cout << "Derived::init\n";
        return 42;
    }

public:
    Derived() {
        cout << "Derived constructor\n";
    }

    void call() override {
        cout << "Derived::call, x = " << x << "\n";
    }
};

int main() {
    Derived d;
    return 0;
}

Derived::init
Derived constructor

Derived::init
Derived constructor

Base constructor: Derived::call, x = 42
Derived constructor

Derived::call, x = <undefined>
Derived::init
Derived constructor