If you can't re-link with the new library, it's no longer ABI compatible and thus it's a major version change. If you can re-link with the new library but some

If you can't re-link with the new library, it's no longer ABI compatible and thus it's a major version change. If you can re-link with the new library but something no longer works, you need to emit lots of very loud warnings when code calls that function.