Strange requirement...

[David Kastrup <dak@gnu.org>]

Hi,

in
(info "(elisp) Common Keywords.")

we have

`:package-version '(PACKAGE . VERSION)'
     This option specifies that the item was first introduced in
     PACKAGE version VERSION, or that its default value was changed in
     that version.  This keyword takes priority over :version.  The
     value of PACKAGE is a symbol and VERSION is a string.  The PACKAGE
     and VERSION must appear in the alist
     `customize-package-emacs-version-alist'.  Since PACKAGE must be
     unique and the user might see it in an error message, a good choice
     is the official name of the package, such as MH-E or Gnus.


   Packages that use the `:package-version' keyword must also update
the `customize-package-emacs-version-alist' variable.

 -- Variable: customize-package-emacs-version-alist
     This alist provides a mapping for the versions of Emacs that are
     associated with versions of a package listed in the
     `:package-version' keyword.  Its elements look like this:

          (PACKAGE (PVERSION . EVERSION)...)

     For each PACKAGE, which is a symbol, there are one or more
     elements that contain a package version PVERSION with an
     associated Emacs version EVERSION.  These versions are strings.
     For example, the MH-E package updates this alist with the
     following:

          (add-to-list 'customize-package-emacs-version-alist
                       '(MH-E ("6.0" . "22.1") ("6.1" . "22.1") ("7.0" . "22.1")
                              ("7.1" . "22.1") ("7.2" . "22.1") ("7.3" . "22.1")
                              ("7.4" . "22.1") ("8.0" . "22.1")))

     The value of PACKAGE needs to be unique and it needs to match the
     PACKAGE value appearing in the `:package-version' keyword.  Since
     the user might see the value in a error message, a good choice is
     the official name of the package, such as MH-E or Gnus.

[...]

This gives, however, no clue about how to deal with declaring versions
of an external package that is _not_ distributed as part of Emacs
(notably AUCTeX).

I think the reasonable behavior would be to just use :package-version
like described, but not add anything to
customize-package-emacs-version-alist, since there is nothing useful
to add there.

Would that lead to reasonable behavior?  If yes, I think we should
document it.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum