On Tue, Dec 10, 2019 at 4:28 AM Adam Porter <adam@alphapapa.net> wrote:

> There are hundreds of thousands, probably millions, of lines of Elisp in
> third-party packages and user configurations in the world.  Removing the
> return value of `push' would be a breaking change affecting innumerable
> users.

Just for the record, our sources have approx. 1,345,500 non-empty,
non-comment lines of lisp. I found 34 uses of the return value of push
(could be a few more that I didn't find, but not many).

That's one use every ~40,000 lines of code, or approx 0,0025% of them.

If code outside has a similar rating, breaking it wouldn't be really
something that should kept us awake.

But anyway, the point is moot, as non-documenting it just means that the
code is mistaken, and will continue to be so. As Stefan as said, nobody
was talking about modifying push's implementation.