#include <type_traits>
#include <utility>
#include <memory>
#include <iostream>

#include <cstdlib>
#include <cassert>

namespace
{

template< typename lambda >
auto
make_scope_guard(lambda && _lambda)
{
    struct lambda_caller
    {

        using pointer = std::decay_t< lambda >;

        void
        operator () (pointer l) const noexcept
        {
            std::forward< lambda >(l)();
        }

    };
    return std::unique_ptr< std::decay_t< lambda >, lambda_caller >(std::forward< lambda >(_lambda));
}

}

int
main()
{
    std::cout << 1 << std::endl;
    {
        std::cout << 2 << std::endl;
        [[gnu::unused]] auto && guard_ = make_scope_guard([&] { std::cout << __PRETTY_FUNCTION__ << std::endl; });
        std::cout << 3 << std::endl;
    }
    std::cout << 5 << std::endl;
    return EXIT_SUCCESS;
}