[zozbot234]

> This doesn't allow any change in behavior when subclassing.

Generally correct, but that's why you should only be "subclassing" abstract interfaces in the first place. Subclassing concrete object methods is a footgun, precisely because you have no way of enforcing which of these "properties" any code will actually be relying on, either at any given point in time or in the future. (Including code that's itself part of the base objects hierarchy and calling possibly-overridden methods, which means subclassing also breaks encapsulation!)

Concrete inheritance is very hard to make sense of semantically in the fully general case; if it's viable at all it is as a kind of mere specialization, and that's what the LSP is trying to get at.

[ByteJockey]

I don't disagree at all. I tend to advocate for very shallow hierarchies in the 5-10% of code that I think benefits from an object oriented style.

But the point of the comment is the formal/common divide rather than the specific example.