The file only contains obsolete definitions, so it really belongs in `lisp/obsolete`. Moving it there will also signal a warning for those people who run old `.elc` files using EIEIO and generated with Emacs<25 and who otherwise might not know about the obsolescence of some of the functions they use. * lisp/emacs-lisp/eieio-compat.el: Move to ... * lisp/obsolete/eieio-compat.el: ... here.