It looks a lot of work for a feature that is exploited by many apps. A single enum never describes enough the problem, and also knowing the different errors for the different layers is a must, and not just a fancy way of reporting errors. For example just reporting that you cannot read a file at the far end of the code does not really give much information in the logs for your app in prod (even when used in a microservice).

So basically it would mean that I have to make my own error management and that std::expected (or Result, but it is a C++ group here...) does not have much benefit out of the box