Re: moving more cl seq/mapping support into core

[Richard Stallman <rms@gnu.org>]

    Here's the thing about the global names "issue" that I find
    particularly irksome:

    (let ((tf "./some-temp-file"))
      (with-temp-file tf
	(insert
	 "(defun reduce (arg1)\n  arg1)"
	 "\n(reduce 'bubba)"))
      (byte-compile-file tf)
      (when (get-buffer "*Compile-Log*")
	(display-buffer "*Compile-Log*"))
      (delete-file tf))

This writes a file that defines `reduce' globally.

    | some-temp-file:1:8:Warning: function reduce used to take 2+ arguments, now
    |     takes 1
    | some-temp-file:3:10:Warning: Function `reduce' from cl package called at
    |     runtime

I guess you had already loaded cl.

The purpose of this warning is to encourage people not to write their code
to call cl at run time.

I think it was intended to operate in files that load cl at compile
time and don't require cl at run time.  The occurrence of the message
in this case seems like a bug.