Hi Emacs,

As an ELPA ":core" package, ERC has a life outside of the emacs.git
tree, where it aims to support the two most recent major releases of
Emacs: currently 27 and 28. Part of that means tending to a menagerie of
adapters here on trunk. However, going forward, we'd like to offload the
bulk of this upkeep to the purpose-built library 'compat'.

The patch below details the changes we'd need, but the crux is really
this addition here:

  @@ -26,6 +26,7 @@
   ;; This mostly defines stuff that cannot be worked around easily.
   
   ;;; Code:
  +(require 'compat nil 'noerror)
   
   ;;;###autoload(autoload 'erc-define-minor-mode "erc-compat")
   (define-obsolete-function-alias 'erc-define-minor-mode

We bring this to your attention in hopes of addressing any concerns that
may arise over its (hopefully imminent) inclusion. FWIW, occasional
external dependencies crop up elsewhere within the Emacs tree. But most,
like `gnus-read-ephemeral-emacs-bug-group', appear to be supplemental
and integrations-focused rather than top-level affairs affecting decent
swaths of code (true in our case for Emacs 27).

I've Cc'd Philip, compat's author, who's far better equipped to field
any nontrivial questions.

Thanks,
J.P.


Related discussions:

  https://lists.gnu.org/archive/html/emacs-devel/2021-09/msg01546.html
  https://lists.gnu.org/archive/html/emacs-devel/2021-10/msg00338.html
  https://lists.gnu.org/archive/html/emacs-erc/2022-07/msg00006.html