#include <cstddef>
#include <iostream>

struct SettingFieldNumber
{
    using Type = size_t;
    using ValueType = size_t;

    Type value;
    bool changed = false;

    explicit SettingFieldNumber(Type x = 0);
    SettingFieldNumber(const SettingFieldNumber & o)
        : value(o.value), changed(o.changed)
    {}

    virtual SettingFieldNumber & operator=(Type x);
    SettingFieldNumber & operator=(const SettingFieldNumber & o)
    {
        if (this != &o)
        {
            value = o.value;
            changed = o.changed;
        }
        return *this;
    }

    operator Type() const { return value; } /// NOLINT
};

int main()
{
    std::cout << "SettingFieldNumber:: size: " << sizeof(getenv("foo") ? SettingFieldNumber() : 0) << "\n";
    std::cout << "SettingFieldNumber:: size: " << sizeof(getenv("foo") ? SettingFieldNumber().value : 0) << "\n";
    return 0;
}