bug#47161: 28.0.50; [feature/native-comp] Failure to native-compile bytecomp.el etc.

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: Andrea Corallo <akrl@sdf.org>,  47161@debbugs.gnu.org
> Date: Tue, 16 Mar 2021 21:27:11 -0400
> 
> > I also suddenly see another byte-compilation message:
> >
> >     ELC      emacs-lisp/byte-opt.elc
> >   Compiler-macro error for cl--block-wrapper: (error "(setf seq-elt) is 
> > already defined as something else than a generic function")
> >   Eager macro-expansion failure: (error "(setf seq-elt) is already defined 
> > as something else than a generic function")
> >
> > What causes this?
> 
> Can you try and reproduce this while `macroexp--debug-eager` is set to
> a non-nil value so we hopefully get a backtrace?

Sorry, it stopped happening for me, so I cannot reproduce this
anymore.