bug#50842: Fwd: bug#50842: 28.0.50; problem with fill-paragraph

[No Wayman]

Apologies. I used the "Reply" button on the bug archive page and 
didn't realize it would just reply to Lars.
I hope I'm forwarding this to the right address so it can be seen 
by all in the thread.

> Ah, that's the missing detail.

Apologies if this is an unwelcome intrusion, but I'm currently 
working on a package
to prevent this type of confusion during bug reproduction:

https://www.github.com/progfolio/yodel


The basic idea is to provide macros which make declaring a 
reproduction case easier.
It runs the test and provides a formatted report which others can 
run and compare results.
The reports can be re-formatted easily after they've been run.
Yodel currently supports github markdown, reddit markdown, Org 
syntax, and can easily be extended to support other formats.

As a case study, I wrote a test for this bug.
The yodel-file macro removes the ambiguity of "Copy this into a 
buffer, do this with point here, etc".
The yodel macro runs the test locally in a temporary, clean Emacs 
environment, and presents the formatted report.
Here's the resultant report in Org syntax:


* YODEL REPORT [2021-09-28 11:12:45]

#+begin_src emacs-lisp :lexical t :results silent
(yodel
  :post*
  (yodel-file
    :point "|"
    :with*
    "From: xxx
To: xxx
Subject: xxx

You wrote:
> | bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla 
> bla bla bla bla bla
>           bla bla bla bla bla bla bla bla bla bla bla bla bla 
>           bla bla bla bla bla
>           bla bla bla bla bla bla bla bla bla bla bla bla bla 
>           bla bla bla bla bla     "
    :then*
    (message-mode)
    (fill-paragraph)
    (print
     (buffer-substring-no-properties
      (point-min)
      (point-max)))))

#+end_src


** STDOUT:

#+begin_src emacs-lisp :lexical t :results silent
"From: xxx
To: xxx
Subject: xxx
--text follows this line--
You wrote:

> bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla 
> bla
bla bla bla > bla bla bla bla bla bla bla bla bla bla bla bla bla 
bla
bla bla bla bla > bla bla bla bla bla bla bla bla bla bla bla bla 
bla
bla bla bla bla bla"
#+end_src

** Environment

- =emacs version=: GNU Emacs 28.0.50 (build 1, 
  x86_64-pc-linux-gnu, X toolkit, cairo version 1.17.4, Xaw3d 
  scroll bars)
 of 2021-09-23
- =system type=: gnu/linux



Just food for thought on how we could better approach reproducing 
bugs.

Thanks,
Nick