Re: defvar'ing constants

[Richard M. Stallman]

    One case I know was consciously make to work is (defvar :foo :foo) so that
    packages using :foo could be kept backward compatible with Emacs-19
    where :foo is a normal variable because keywords don't exist.
    Whether we should still cater to such thing is another question.

I had forgotten about that, because Emacs 19 was so long ago.

I think it is ok to forget about this, but _if_ the change bothers
people, we could change defvar to once again allow that case and that
case only.