bool save_config() {
    return write_file("config.json");
}

save_config();

[[nodiscard]]
bool save_config() {
    return write_file("config.json");
}

save_config(); // warning

if (!save_config()) {
    std::cerr << "Config was not saved\n";
}

[[nodiscard]]
std::optional<User> find_user(int id);

[[nodiscard]]
bool is_valid_token(std::string_view token);

(void)save_config();

Продолжай читать на Habr

auto item = std::pair{1, std::string("ready")};

auto [id, name] = item;

name = "cpp";

std::cout << item.second; // ready

auto& [id, name] = item;

name = "cpp";

std::cout << item.second; // cpp

for (auto [key, value] : users) {
    value.active = false;
}

for (auto& [key, value] : users) {
    value.active = false;
}

for (const auto& [key, value] : users) {
    std::cout << key << value.name;
}