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

Answer 1

The reason of this warning is a GNU policy which does not want a package cl to be used in Elisp. But it would be foolish as well to prohibit it completely. So they decided to show a warning.

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