Hi ! After a short discussion with Miles Bader, it seems that the usage of run-time functions in the cl package is strongly discouraged in Emacs (but using macros is not a problem).
So, the correct usage is (eval-when-compile (require 'cl)) But not (eval-and-compile (require 'cl)) I've seen someone changed this in the "wrong" way. It would be nice to revert that change, and probably modify the code accordingly. Thanks, -- Matthieu
