That's not a fragile base, that's just a fragile class. You can break APIs for all kinds of users, including derived classes. Some APIs are aimed towards deriv

That's not a fragile base, that's just a fragile class. You can break APIs for all kinds of users, including derived classes. Some APIs are aimed towards derived classes, like protected members and virtual functions, but that doesn't make the issue fundamentally different. It's just breaking APIs. Point is, in C++ you have to opt-in to make these API surfaces, they are not the default.