bug#64535: 30.0.50; Spurious newlines in `prin1` output

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: 64535-done@debbugs.gnu.org
> Date: Thu, 13 Jul 2023 19:11:48 -0400
> 
> >> Can we get rid of this quirk now, please?
> >
> > I'm okay with getting rid of it, with two conditions:
> >
> >   . removing newline insertion in the scenario of bug#2866 leaves
> >     Emacs sufficiently performant, even in the unoptimized build, and
> >   . we will still insert a newline if long-line-threshold is nil
> 
> That means we'd keep the code and make it even larger.

The second item, maybe.  What about the first -- is bug#2866 solved by
long-line handling in Emacs 29?

> > IOW, I don't want us to bring back regressions as result of
> > this cleanup.
> 
> That wouldn't be a cleanup, then.  IOW you're asking me to make the
> quirk even bigger.  I'd rather keep the quirk as-is, in that case.

Sorry, I don't understand: what was the reason for you to start this
discussion?  IOW, why is it good to get rid of the code which inserts
those newlines?  I don't suppose you wanted to bring back the bug
which was the reason for adding that code, did you?

I can suggest another solution: remove that code, but make sure
long-line-threshold is reset to its default value locally in the
buffer where prin1 is producing its output?  Would that be more
acceptable?