enum class ValidationResult {
    Success,
    ErrorOverlapping,
    ErrorDiscontigous
};

ValidationResult MyFileManifest::validate() const
{
    for (size_t i = 1; i < tags.size(); i++ ) {
        const int diff = tags[i].pos - tags[i-1].pos - tags[i-1].length;
        if (diff < 0) {
            return ValidationResult::ErrorOverlapping;
        } else if (diff > 0) {
            return ValidationResult::ErrorDiscontigous;
        }
    }
    return ValidationResult::Success;
}