>From 23b193168c03c9d36307986f87f2789cafae9b41 Mon Sep 17 00:00:00 2001
From: "F. Jason Park" <jp@neverwas.me>
Date: Thu, 16 Feb 2023 22:51:42 -0800
Subject: [PATCH 0/3] *** NOT A PATCH ***

*** BLURB HERE ***

F. Jason Park (3):
  [5.6] Don't associate ERC modules with undefined groups
  [5.6] Warn when setting minor-mode vars for ERC modules
  [5.6] Fill doc strings for ERC modules.

 lisp/erc/erc-capab.el      |   1 +
 lisp/erc/erc-common.el     | 143 +++++++++++++++++++++++++++++++++----
 lisp/erc/erc.el            |   3 +-
 test/lisp/erc/erc-tests.el |  84 +++++++++++++++++-----
 4 files changed, 200 insertions(+), 31 deletions(-)

Interdiff:
diff --git a/lisp/erc/erc-common.el b/lisp/erc/erc-common.el
index cc278428d5d..6d09ac25a0a 100644
--- a/lisp/erc/erc-common.el
+++ b/lisp/erc/erc-common.el
@@ -130,13 +130,14 @@ erc--normalize-module-symbol
   (or (cdr (assq symbol erc--module-name-migrations)) symbol))
 
 (defvar erc--inside-mode-toggle-p nil
-  "Non-nil when a mode toggle is updating module membership.
-This serves as a flag to inhibit the mutual recursion that
-otherwise occurs between an ERC-defined minor-mode function, such
+  "Non-nil when a module's mode toggle is updating module membership.
+This serves as a flag to inhibit the mutual recursion that would
+otherwise occur between an ERC-defined minor-mode function, such
 as `erc-services-mode', and the custom-set function for
 `erc-modules'.  For historical reasons, the latter calls
 `erc-update-modules', which, in turn, enables the minor-mode
-functions for all member modules.")
+functions for all member modules.  Also non-nil when a mode's
+widget runs its set function.")
 
 (defun erc--assemble-toggle (localp name ablsym mode val body)
   (let ((arg (make-symbol "arg")))
@@ -155,23 +156,29 @@ erc--assemble-toggle
                        (,ablsym))
                    (setq ,mode ,val)
                    ,@body)))
-           `((unless erc--inside-mode-toggle-p
-               ,(if val
-                    `(cl-pushnew ',(erc--normalize-module-symbol name)
-                                 erc-modules)
-                  `(setq erc-modules
-                         (delq ',(erc--normalize-module-symbol name)
-                               erc-modules))))
+           ;; No need for `default-value', etc. because a buffer-local
+           ;; `erc-modules' only influences the next session and
+           ;; doesn't survive the major-mode reset that soon follows.
+           `((unless
+                 (or erc--inside-mode-toggle-p
+                     ,@(let ((v `(memq ',(erc--normalize-module-symbol name)
+                                       erc-modules)))
+                         `(,(if val v `(not ,v)))))
+               (let ((erc--inside-mode-toggle-p t))
+                 (customize-set-variable
+                  'erc-modules (,(if val 'cons 'delq)
+                                ',(erc--normalize-module-symbol name)
+                                erc-modules))))
              (setq ,mode ,val)
              ,@body)))))
 
 ;; This is a migration helper that determines a module's `:group'
 ;; keyword argument from its name or alias.  A (global) module's minor
-;; mode variable will appear under the group's Custom menu.  Like
+;; mode variable appears under the group's Custom menu.  Like
 ;; `erc--normalize-module-symbol', it must run when the module's
 ;; definition (rather than that of `define-erc-module') is expanded.
-;; For corner cases where this fails and where the catch-all of `erc'
-;; is inappropriate, (global) modules can declare a top-level
+;; For corner cases in which this fails or the catch-all of `erc' is
+;; more inappropriate, (global) modules can declare a top-level
 ;;
 ;;   (put 'foo 'erc-group 'erc-bar)
 ;;
diff --git a/test/lisp/erc/erc-tests.el b/test/lisp/erc/erc-tests.el
index e5db78ef2e1..8e41d428ce9 100644
--- a/test/lisp/erc/erc-tests.el
+++ b/test/lisp/erc/erc-tests.el
@@ -1337,16 +1337,22 @@ define-erc-module--global
                       (defun erc-mname-enable ()
                         "Enable ERC mname mode."
                         (interactive)
-                        (unless erc--inside-mode-toggle-p
-                          (cl-pushnew 'mname erc-modules))
+                        (unless (or erc--inside-mode-toggle-p
+                                    (memq 'mname erc-modules))
+                          (let ((erc--inside-mode-toggle-p t))
+                            (customize-set-variable
+                             'erc-modules (cons 'mname erc-modules))))
                         (setq erc-mname-mode t)
                         (ignore a) (ignore b))
 
                       (defun erc-mname-disable ()
                         "Disable ERC mname mode."
                         (interactive)
-                        (unless erc--inside-mode-toggle-p
-                          (setq erc-modules (delq 'mname erc-modules)))
+                        (unless (or erc--inside-mode-toggle-p
+                                    (not (memq 'mname erc-modules)))
+                          (let ((erc--inside-mode-toggle-p t))
+                            (customize-set-variable
+                             'erc-modules (delq 'mname erc-modules))))
                         (setq erc-mname-mode nil)
                         (ignore c) (ignore d))
 
-- 
2.39.1