bug#54079: 29.0.50; Method dispatching eratically fails

[Alan Mackenzie]

Hello, Michael and Lars.

On Fri, Mar 04, 2022 at 03:08:05 +0100, Michael Heerdegen wrote:
> Michael Heerdegen <michael_heerdegen@web.de> writes:

> > This short recipe gives me the same error in emacs -Q:

> > (byte-compile-file
> >  "/home/micha/software/emacs/lisp/emacs-lisp/cl-generic.el")
> > (require 'gnus-search)

Thanks for such an easy to use recipe (despite the troubles you had
coming up with it ;-).

> Small addition: it seems that all issues mentioned disappear when I
> avoid any byte compilation in my session.  Compilation of `defstruct's
> seems to be the culprit (hypothesis).

The biggest clue is in that error message

    #<symbol let at 15662>

..  At position 15662 in file cl-generic.el, there is indeed a `let'.
It's the first symbol inside a defun, and that defun is inside an
eval-and-compile.

It seems that the positions are not being removed from the evaluation of
the defun form done by eval-and-compile.  This is the bug.

> Would be good to fix this problem not too late.  I think it will
> irritate or distract other people, too.

It irritates me.  ;-)  I'll fix it.  Maybe this evening, maybe over the
weekend.

> Michael.

-- 
Alan Mackenzie (Nuremberg, Germany).