So, we add class aliases when rename stuff... What "deprecation" policy should we be using to remove them? Remove the next major release (especially if we've cleaned up usages in core/extensions?)
I note we don't add since or deprecated tags to the calls, so it's harder to track them... Maybe we should start doing that, rather than having to git blame for them all
We should be following the standard deprecation policy, with the caveat that it might not be technically possible to hard deprecate (like class members, constants, etc.).
We should definitely add @since and @deprecated tags to the class alias calls, and ensure that it's mentioned in the release notes.
https://phabricator.wikimedia.org/T195576 already filed for backfilling
Hard deprecation would be nice, but isn't always necessary. If we're not at least using deprecated tags, we're doing ourselves and other people a dis-service