Re: Problem with new cl-lib 0.6 in ELPA

[Steve Purcell]

On 8/01/2017 11:39 AM, Tom Tromey <address@hidden> wrote:

Steve> The new cl-lib version now declares a package dependency on Emacs
Steve> 21, which actually renders it completely uninstallable in Emacs <
Steve> 24, since the only versions of package.el usable in Emacs 23.x
Steve> have no concept of built-in packages like "emacs".

Something is weird here, because "emacs" as a package was in package.el
at the very beginning.  This is also documented in
(info "(elisp) Library Headers")

I'm not aware that there is any version of package.el compatible with 23.4 which supports both multiple archives and the "emacs" pseudo-package.

The problem reported on this thread occurred in the context of a Travis build on 23.4 which used the most recent package.el from the emacs tree known to be compatible with that older Emacs version. The job failure reported that the package emacs-21 was unavailable:

https://travis-ci.org/purcell/emacs.d/jobs/189410416

Here's the package.el version in question: http://repo.or.cz/w/emacs.git/blob_plain/ba08b24186711eaeb3748f3d1f23e2c2d9ed0d09:/lisp/emacs-lisp/package.el

It's an unfortunate situation, because we'd either have to backport a better package.el, or we must continue to avoid adding such backwards-incompatible dependencies to the extent we care about 23.x. (package.el already has at least one other unfortunate compatibility quirk, in that recent versions allow the version number to be omitted in Package-Requires headers, while older versions consider that invalid.)