More clearly define local module behavior in ERC

* doc/misc/erc.texi (Modules): Label all local modules as being such.
Move `querypoll' to the auxiliary section.  Rework entire "Local
Modules" portion.
* lisp/erc/erc-goodies.el (erc-keep-place-indicator-mode)
(erc-command-indicator-mode): Mention what buffer types they operate in.
* lisp/erc/erc-nicks.el (erc-nicks-mode): Mention the mode is enabled in
all buffers.
* lisp/erc/erc-notify.el (erc-querypoll-mode): Mention which buffers it
operates in.
* lisp/erc/erc-sasl.el (erc-sasl-mode): Disable completely in target
buffers so its mode variable is nil.
* lisp/erc/erc-services.el (erc-services-regain-mode): Disable in target
buffers.
* lisp/erc/erc.el (erc-open): When activating local modules, skip those
that have just been enabled by a fellow module.  Do this even though
their setup code is meant to be idempotent.
* test/lisp/erc/erc-scenarios-base-local-modules.el
(erc-scenarios-base-local-modules--toggle-helpers): Revise to assert
current behavior.  (Bug#57955)

6 files changed, 24 insertions, 18 deletions

diff --git a/lisp/erc/erc-goodies.el b/lisp/erc/erc-goodies.el
index cfd0d3415ea..24a3205e0cd 100644
--- a/lisp/erc/erc-goodies.el
+++ b/lisp/erc/erc-goodies.el
@@ -372,7 +372,9 @@ than the indicator's position."
   "Buffer-local `keep-place' with fringe arrow and/or highlighted face.
 Play nice with global module `keep-place' but don't depend on it.
 Expect that users may want different combinations of `keep-place'
-and `keep-place-indicator' in different buffers."
+and `keep-place-indicator' in different buffers.
+
+This module is local to individual buffers."
   ((cond (erc-keep-place-mode)
          ((memq 'keep-place erc-modules)
           (erc-keep-place-mode +1))
@@ -589,7 +591,9 @@ message's speaker."
 Skip those appearing in `erc-noncommands-list'.
 
 Users can run \\[erc-command-indicator-toggle-hidden] to hide and
-reveal echoed command lines after they've been inserted."
+reveal echoed command lines after they've been inserted.
+
+This module is local to individual buffers."
   ((add-hook 'erc--input-review-functions
              #'erc--command-indicator-permit-insertion 80 t)
    (erc-command-indicator-toggle-hidden -1))
diff --git a/lisp/erc/erc-nicks.el b/lisp/erc/erc-nicks.el
index b0629f7754c..a3e9b1f7b46 100644
--- a/lisp/erc/erc-nicks.el
+++ b/lisp/erc/erc-nicks.el
@@ -541,7 +541,9 @@ Abandon search after examining LIMIT faces."
   nick-object)
 
 (define-erc-module nicks nil
-  "Uniquely colorize nicknames in target buffers."
+  "Uniquely colorize nicknames in target buffers.
+
+This module is local per connection."
   ((if erc--target
        (progn
          (erc-with-server-buffer
diff --git a/lisp/erc/erc-notify.el b/lisp/erc/erc-notify.el
index 82754cb1989..1e04c90177e 100644
--- a/lisp/erc/erc-notify.el
+++ b/lisp/erc/erc-notify.el
@@ -299,7 +299,8 @@ like `nickbar', to provide UI feedback when changes occur.
 Once ERC implements the `monitor' extension, this module will serve as
 an optional fallback for keeping query-participant rolls up to date on
 servers that lack support or are stingy with their allotments.  Until
-such time, this module should be considered experimental.
+such time, this module should be considered experimental and only really
+useful for bots and other non-interactive Lisp programs.
 
 This is a local ERC module, so selectively polling only a subset of
 query targets is possible but cumbersome.  To do so, ensure
@@ -307,7 +308,8 @@ query targets is possible but cumbersome.  To do so, ensure
 as appropriate in desired query buffers.  To stop polling for the
 current connection, toggle off the command \\[erc-querypoll-mode] from a
 server buffer, or run \\`M-x C-u erc-querypoll-disable RET' from a
-target buffer."
+target buffer.  Note that this module's minor mode must remain active in
+at least the server buffer."
   ((if erc--target
        (if (erc-query-buffer-p)
            (progn ; accommodate those who eschew `erc-modules'
diff --git a/lisp/erc/erc-sasl.el b/lisp/erc/erc-sasl.el
index a16f554f2d1..5228fc5e5aa 100644
--- a/lisp/erc/erc-sasl.el
+++ b/lisp/erc/erc-sasl.el
@@ -34,13 +34,6 @@
 ;;
 ;; - Implement a proxy mechanism that chooses the strongest available
 ;;   mechanism for you.  Requires CAP 3.2 (see bug#49860).
-;;
-;; - Integrate with whatever solution ERC eventually settles on to
-;;   handle user options for different network contexts.  At the
-;;   moment, this does its own thing for stashing and restoring
-;;   session options, but ERC should make abstractions available for
-;;   all local modules to use, possibly based on connection-local
-;;   variables.
 
 ;;; Code:
 (require 'erc)
@@ -315,9 +308,10 @@ If necessary, pass PROMPT to `read-passwd'."
 
 (define-erc-module sasl nil
   "Non-IRCv3 SASL support for ERC.
-This doesn't solicit or validate a suite of supported mechanisms."
-  ;; See bug#49860 for a CAP 3.2-aware WIP implementation.
-  ((unless erc--target
+This local module only enables its minor mode in server buffers, and it
+doesn't currently solicit or validate supported mechanisms."
+  ((if erc--target
+       (erc-sasl-mode -1)
      (setq erc-sasl--state (make-erc-sasl--state))
      ;; If the previous attempt failed during registration, this may be
      ;; non-nil and contain erroneous values, but how can we detect that?
diff --git a/lisp/erc/erc-services.el b/lisp/erc/erc-services.el
index 429424117eb..25da873076e 100644
--- a/lisp/erc/erc-services.el
+++ b/lisp/erc/erc-services.el
@@ -613,8 +613,10 @@ In practical terms, this means that this module, which is still
 somewhat experimental, is likely only useful in conjunction with
 SASL authentication or CertFP rather than the traditional approach
 provided by the `services' module it shares a library with (see Info
-node `(erc) SASL' for more)."
-  nil nil localp)
+node `(erc) SASL' for more).
+
+This local module's minor mode is only active in server buffers."
+  ((when erc--target (erc-services-regain-mode -1))) nil localp)
 
 (cl-defmethod erc--nickname-in-use-make-request
   ((want string) temp &context (erc-server-connected null)
diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index afa8e0a7b72..0d72b46360e 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -2662,7 +2662,9 @@ side effect of setting the current buffer to the one it returns.  Use
     (erc--initialize-markers old-point continued-session)
     (erc-determine-parameters server port nick full-name user passwd)
     (save-excursion (run-mode-hooks)
-                    (dolist (mod (car delayed-modules)) (funcall mod +1))
+                    (dolist (mod (car delayed-modules))
+                      (unless (and (boundp mod) (symbol-value mod))
+                        (funcall mod +1)))
                     (dolist (var (cdr delayed-modules)) (set var nil)))
 
     ;; Saving log file on exit