Un-deprecate oset and oset-default

For discussion see the following threads:
https://lists.gnu.org/archive/html/emacs-devel/2020-05/msg00630.html
https://lists.gnu.org/archive/html/emacs-devel/2020-05/msg00674.html
https://lists.gnu.org/archive/html/emacs-devel/2020-06/msg00099.html

* lisp/emacs-lisp/eieio.el (oset, oset-default): Un-deprecate.
* lisp/emacs-lisp/eieio-core.el (eieio-oref): Declare gv-setter here
instead of in lisp/emacs-lisp/eieio.el.  Suggested by
Stefan Monnier <monnier@iro.umontreal.ca>.
(eieio-oref-default): Add gv-setter declaration.
* etc/NEWS: Announce these changes.
* doc/misc/eieio.texi (Accessing Slots): Document oref and
oref-default as generalized variables.  Consistently document
getters before setters.
* test/lisp/emacs-lisp/eieio-tests/eieio-tests.el: Use
lexical-binding.
(eieio-test-13-init-methods): Simplify.
(eieio-test-33-instance-tracker): Declare IT-list as special.

1 files changed, 3 insertions, 2 deletions

diff --git a/test/lisp/emacs-lisp/eieio-tests/eieio-tests.el b/test/lisp/emacs-lisp/eieio-tests/eieio-tests.el
index 34c20b2003f..21adc91e555 100644
--- a/test/lisp/emacs-lisp/eieio-tests/eieio-tests.el
+++ b/test/lisp/emacs-lisp/eieio-tests/eieio-tests.el
@@ -1,4 +1,4 @@
-;;; eieio-tests.el -- eieio tests routines
+;;; eieio-tests.el -- eieio test routines -*- lexical-binding: t -*-
 
 ;; Copyright (C) 1999-2003, 2005-2010, 2012-2020 Free Software
 ;; Foundation, Inc.
@@ -356,7 +356,7 @@ METHOD is the method that was attempting to be called."
     (oset a test-tag 1))
 
   (let ((ca (class-a)))
-    (should-not (/=  (oref ca test-tag) 2))))
+    (should (= (oref ca test-tag) 2))))
 
 
 ;;; Perform slot testing
@@ -852,6 +852,7 @@ Subclasses to override slot attributes.")
   "Instance Tracker test object.")
 
 (ert-deftest eieio-test-33-instance-tracker ()
+  (defvar IT-list)
   (let (IT-list IT1)
     (should (setq IT1 (IT)))
     ;; The instance tracker must find this