bug#29664: 26.0.90; Auto Hscroll Mode + Visual Line Mode + Truncate don't work well together

[Kaushal Modi <kaushal.modi@gmail.com>]

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On Mon, Dec 11, 2017 at 3:57 PM Eli Zaretskii <eliz@gnu.org> wrote:

>
> Why are you turning on both visual-line-mode and truncate-lines?
> These are mutually exclusive: the former is for wrapping long
> continued lines, the latter is for not continuing lines at all.
>
> What am I missing?
>

Yes, I understand that. But they were both enabled by mistake.

- The visual line mode was enabled by default in org-mode-hook
- And I happened to have "# eval: (toggle-truncate-lines 1)" in the Local
Variables footer in one of the Org files.

There were no signs of problem until C-a and C-e started misbehaving that
way.

Should emacs do the "right thing" and auto-disable the other if one got
enabled, or throw a warning?

This problem with C-a and C-e does not happen if skip this part in the test
setup:

 (setq auto-hscroll-mode 'current-line)

- C-a works perfectly
- C-e does not jump instantly to the EOL, but progressively goes to the EOL
on hitting C-e, and eventually gets there (interesting behavior).

So at least with the default value of auto-hscroll-mode, a user is not
stuck wondering why C-a/C-e stopped working, even if they enabled
visual-line-mode and toggle-truncate-lines simultaneously by mistake.

PS: I noticed that the email client or the debbugs server auto-inserted
newlines in my test function.. I intend that insert form to insert a string
without any inbetween newlines.. like this:

(insert (concat "\n\ndlkasdjf lkdkmnf kd aksdjkldj laksdjflkasdf "
                "aldksflakdjf alksdjldf lksdfjldkj lkjdfad "
                "falksdflj asldkfjlasdf fjlaksdjflkj asdf "
                "lasdkfalkds alsdfkj sdf lsdkfj sldkfjlksdjf "
                "asldkfjlksdjfowieur nxc"))
-- 

Kaushal Modi

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