lisp - In Emacs, what does this error mean? "Warning: cl package required at runtime"

Question

I am byte-compiling a module. It gives me this warning:

 Warning: cl package required at runtime

Why is this a warning? I am well aware that I am using the cl package. In fact there is a (require 'cl) statement in the module.

Is there something wrong with using the cl stuff?

If so, is there a list of published workarounds? The main things I use are mapcan and delete-duplicates.

question from:https://stackoverflow.com/questions/5019724/in-emacs-what-does-this-error-mean-warning-cl-package-required-at-runtime

Answer 1

Just in case someone reads this on his quest for proper use of cl: The methods described here are now deprecated.

As least as of emacs 24, instead of cl you should use cl-lib or, if the macros suffice, cl-macs. These are new versions of cl that work with a clean namespace. E.g. instead of defun* you have cl-defun.

The old cl-package now is only for backward-compatibility and shouldn't be used in new code.