[tialaramex]

> In today's Rust, since the Error type of a Result is an explicit part of a function's signature, such a change is very noisy to the library's maintainer: it entails either modifying the signature of the public function to return a different error type, or modifying the Error type itself, which is also public.

For what it's worth, if you expect this might happen, you should give the enum the [[non_exhaustive]] attribute. This attribute says I, the implementer, know how many of these there are, and in my code I can exhaustively enumerate them e.g. in a pattern match, however, you the 3rd party programmer using this crate, must assume you can't know how many there are, and therefore must write a default match to handle others, even if there seem to be no others when you write it.

Once you do this, you don't cause a compatibility break by adding a new item.