#include <array>
#include <cassert>
#include <cstddef>
#include <iostream>
#include <memory_resource>
#include <string>
#include <vector>

std::string build_name() {
    alignas(std::max_align_t) std::array<std::byte, 1024> buffer{};
    std::pmr::monotonic_buffer_resource arena(buffer.data(), buffer.size());
    std::string result;
    {
        std::pmr::vector<std::pmr::string> names{&arena};
        names.reserve(2);
        names.emplace_back("alpha");
        names.emplace_back("beta");
        assert(names[0] == "alpha" && names[1] == "beta");
        assert(names[0].get_allocator().resource() == &arena);
        result.assign(names[0].data(), names[0].size());
        result += ':';
        result.append(names[1].data(), names[1].size());
    }
    arena.release();
    return result;
}

int main() {
    std::string name = build_name();
    assert(name == "alpha:beta");
    std::cout << name << '\n';
}