Any mode requiring `cider-common` produces error Symbol's variable is void: xref-etags-location

[sktoiva]

Expected behavior

Opening a .clj file succeeds without errors.

Actual behavior

Opening a .clj file that enables any mode that requires cider-common produces error Symbol's variable is void: xref-etags-location

Steps to reproduce the problem

Using emacs version greater than 25.1 should reproduce the problem by producing a warning. Using emacs version greater than 28 should produce an error.

Enabling for example clj-refactor-mode produces the error.

Further notes

cider-common.el requires etags here: https://github.com/clojure-emacs/cider/blob/master/cider-common.el#L31

That's required only for function find-tag-marker-ring (https://github.com/clojure-emacs/cider/blob/master/cider-common.el#L154).

That's obsolete since emacs 25.1 , but emacs 28 removed it completely.

The correct way should be, to my knowledge, to first (require 'xref) and then use xref-push-marker-stack instead of find-tag-marker-ring.

Here's a similar issue in haskell-mode: haskell/haskell-mode#459

Environment & Version information

CIDER version information

1.2.0snapshot

Emacs version

GNU Emacs 28.0.50 (build 1, x86_64-apple-darwin20.6.0, NS appkit-2022.60 Version 11.5.2 (Build 20G95)) of 2021-08-27

Operating system

macOS Big Sur 11.6