Also see this link:
https://old.reddit.com/r/emacs/comments/as8cri/diskusageel_a_disk_usage_analyzer_for_emacs/egxk1z0/

Purcell argues that Stefan should not have used `eval-when-compile' for
`cl-lib`:

--8<---------------cut here---------------start------------->8---
(eval-when-compile (require 'cl-lib))
--8<---------------cut here---------------end--------------->8---

because `cl-first' is used in some places.

I'd tend to agree with Purcell.  Thoughts?

-- 
Pierre Neidhardt
https://ambrevar.xyz/