[viraptor]

> when library signatures change, and some library function is suddenly gone.

No, no, no. This is not how you fix critical / security issues in a well maintained system. You either backport a single patch that fixes the problem without changing any signatures, or if you support a very old, incompatible software you reimplement the fix yourself. Then the release is not a new library. It's the old one + fix.

This is what the proper package maintenance is about. No functions should ever be "suddenly gone".

Also if you say in your installation requirements "this software requires libfoo >= 1.2.3, < 2.3.4", no sane package maintainer will disagree. Your application may be patched in the packaging process to work with a different supplied version, but most likely it will just get what's needed.

[homeomorphic]

I think this is a key point that many people overlook the importance of when pressuring, say, Debian or Ubuntu maintainers for new package versions inside of a single release.