Re: A ton of marker entry in buffer-und-list

[Eli Zaretskii]

> From: Yuan Fu <casouri@gmail.com>
> Date: Thu, 25 Feb 2021 23:32:33 -0500
> 
> I’ve been playing around with undo recently. I used primitive-undo to undo 
> some entries in the buffer-undo-list, and a ton of (#marker . -1) was added 
> to the buffer-undo-list:
> 
> (nil
>  ("a" . 27)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
>  (#<marker at 27 in a> . -1)
> 
> … hundreds of this.
> 
> Any idea of what is happening? What is this marker?

Doesn't the ELisp manual provide an answer to that question?  It does
describe the structure and the meaning of such an element in
undo-list.