bug#40968: 28.0.50; (apply nil)

[Drew Adams]

> I think there's consensus, then. 

FTR, FWIW: Not a consensus that includes me.

I'm in favor of making an incompatible change,
to align Emacs with Common Lisp's more reasonable
behavior.

As I said:

  Common Lisp is unequivocally in the camp of
  requiring at least two args.

  And if Elisp follows that (which I think it should,
  unless someone can present a good use case for just
  (apply FUNCTION)), then it should raise an error if
  there are not at least two args.

The only good case presented was to say that this
would be an incompatible change.  Yes, it would,
and we should make it.

If you want to, temporarily, issue a compile-time
and runtime warning, instead of raising an error,
OK.  But Emacs should wean code and users off of
the undesirable (IMO) behavior that's been allowed.
The doc should be changed to discourage such use,
and users should be warned that it's deprecated.

Just one, non-consensual, opinion.