bug#50331: 28.0.50; Propose to obsolete cwarn.el

[Eli Zaretskii]

> From: Zhiwei Chen <condy0919@gmail.com>
> Cc: 50331@debbugs.gnu.org,  andlind@gmail.com
> Date: Thu, 02 Sep 2021 16:12:03 +0800
> 
> Why would I like to obsolete cwarn?
> 
> Actually, I'm making an introduction to Emacs builtin modes (in Chinese)
> to see how powerful the vanilla Emacs is. But I found, Emacs is not so
> orthogonal in functionality. e.g., `whitespace-mode' provides
> `whitespace-cleanup' while simple.el has `delete-trailing-whitespace'.
> Is it time to do subtraction for Emacs? There are too many packages
> merged into Emacs, but a few are removed from Emacs (to elpa maybe).

That's true, and one way we have for doing that is moving some stuff
to GNU ELPA.  But that is WIP, and we didn't yet figure out how to
move stuff to ELPA from core without punishing our users.  So we need
to wait for that work to be completed before we can talk about making
Emacs core thinner.

In any case, obsoleting packages is not the right way of doing that,
IMO: there's nothing obsolete in a package that offers some
functionality which doesn't have a 1:1 replacement.

> The main reason for obsoleting cwarn is that its functionality can be
> superseded by flycheck/flymake.

Those packages require a compiler to be installed, which is one
prerequisite cwarn doesn't have.  And I personally don't yet feel
flymake is functional enough and stable enough to be a complete
replacement for specialized packages like cwarn; if nothing else,
flymake takes much more resources than cwarn.

(flycheck is not relevant, since it is not part of Emacs, and probably
never will be.)

> The result of https://grep.app/search?q=cwarn-mode shows that there
> are few users of cwarn.

That's not enough, because if you are one of those few users, removing
the package will deliver a blow, and knowing that you are a member of
a small group doesn't help.

> Of course this result may be wrong, after all https://grep.app/
> only searches the git repo and all data on the Internet. The safe way to
> do this is to raise a poll and let the community decide if cwarn should
> be removed. Since Emacs is such a monster of 40yrs, the expected result
> is that most users never know there is a package named cwarn.

In a recent discussion on Reddit, it turned out many don't know about
dabbrev.el as well, but I hope no one will propose to obsolete or
remove it on those grounds.

So I think we should not obsolete cwarn for now.