what about just using the first line of ChangeLog? though this gets
updated more often than the wire protocl changes it doesn't require
any extra work on the part of slime contcributors. what's worse?
spurious protocol mismatch errors or having to update slime too often?

you could then #.(file-write-date-of-slime.el) somwhere in swank.lisp, but that brings the same problem: it's will much more often signal then actually reasonable.

but if it's only a big fat warning then imho it's fine...

--
- attila

"- The truth is that I've been too considerate, and so became unintentionally cruel...
- I understand.
- No, you don't understand! We don't speak the same language!"
(Ingmar Bergman - Smultronstället)