>From 171dbaefbdc47154b21aa7f7e8c980958f983313 Mon Sep 17 00:00:00 2001
From: "F. Jason Park" <jp@neverwas.me>
Date: Tue, 4 Jul 2023 23:21:25 -0700
Subject: [PATCH 0/4] *** NOT A PATCH ***

*** BLURB HERE ***

F. Jason Park (4):
  [5.6] Respect existing invisibility props in erc-stamp
  [5.6] Simplify erc-button-add-nickname-buttons
  [5.6] Add text props for CTCPs and speakers in ERC
  [5.6] Handle composite faces better in erc-display-message

 etc/ERC-NEWS                         |  15 +++
 lisp/erc/erc-backend.el              |  39 +++----
 lisp/erc/erc-button.el               |  78 +++++++------
 lisp/erc/erc-dcc.el                  |  16 +--
 lisp/erc/erc-fill.el                 |  25 +++--
 lisp/erc/erc-match.el                |  14 +--
 lisp/erc/erc-sasl.el                 |   8 +-
 lisp/erc/erc-stamp.el                |  20 +++-
 lisp/erc/erc-track.el                |  12 +-
 lisp/erc/erc.el                      |  99 +++++++++++++----
 test/lisp/erc/erc-button-tests.el    |   2 +-
 test/lisp/erc/erc-fill-tests.el      |   5 +-
 test/lisp/erc/erc-scenarios-match.el | 160 +++++++++++++++++++++++----
 13 files changed, 347 insertions(+), 146 deletions(-)

Interdiff:
diff --git a/etc/ERC-NEWS b/etc/ERC-NEWS
index 5665b760ea9..40bcd934772 100644
--- a/etc/ERC-NEWS
+++ b/etc/ERC-NEWS
@@ -224,6 +224,21 @@ The 'fill' module is now defined by 'define-erc-module'.  The same
 goes for ERC's imenu integration, which has 'imenu' now appearing in
 the default value of 'erc-modules'.
 
+*** 'erc-display-message' combines faces when 'type' is a list.
+Users may notice that ERC now renders messages passed to the
+convenience function 'erc-display-error-notice' in a combination of
+'erc-error-face' and 'erc-notice-face'.  This is merely a consequence
+of that function being a wrapper around 'erc-display-message', which
+has gotten smarter about how it treats face properties when its 'type'
+parameter is a list.  Originally, ERC's authors intended to display
+both server-originating and ERC-generated errors in this style, but
+due to various complications, that intent was never realized until
+this release, and even now only partially so.  Indeed, to minimize
+churn, the effect has been limited to internal and usage errors.  For
+third-party code, the key take away is that more 'font-lock-face'
+properties encountered in the wild may be combinations of faces rather
+than simple ones.
+
 *** Prompt input is split before 'erc-pre-send-functions' has a say.
 Hook members are now treated to input whose lines have already been
 adjusted to fall within the allowed length limit.  For convenience,
diff --git a/lisp/erc/erc-backend.el b/lisp/erc/erc-backend.el
index f1b51f9234a..bf21ec96225 100644
--- a/lisp/erc/erc-backend.el
+++ b/lisp/erc/erc-backend.el
@@ -148,7 +148,6 @@ erc-whowas-on-nosuchnick
 (declare-function erc-current-time "erc" (&optional specified-time))
 (declare-function erc-default-target "erc" nil)
 (declare-function erc-delete-default-channel "erc" (channel &optional buffer))
-(declare-function erc-display-error-notice "erc" (parsed string))
 (declare-function erc-display-server-message "erc" (_proc parsed))
 (declare-function erc-emacs-time-to-erc-time "erc" (&optional specified-time))
 (declare-function erc-format-message "erc" (msg &rest args))
@@ -2411,47 +2410,47 @@ erc-server-322-message
     (when erc-whowas-on-nosuchnick
       (erc-log (format "cmd: WHOWAS: %s" nick/channel))
       (erc-server-send (format "WHOWAS %s 1" nick/channel)))
-    (erc-display-message parsed '(notice error) 'active
+    (erc-display-message parsed 'error 'active
                          's401 ?n nick/channel)))
 
 (define-erc-response-handler (402)
   "No such server." nil
-  (erc-display-message parsed '(notice error) 'active
+  (erc-display-message parsed 'error 'active
                        's402 ?c (cadr (erc-response.command-args parsed))))
 
 (define-erc-response-handler (403)
   "No such channel." nil
-  (erc-display-message parsed '(notice error) 'active
+  (erc-display-message parsed 'error 'active
                        's403 ?c (cadr (erc-response.command-args parsed))))
 
 (define-erc-response-handler (404)
   "Cannot send to channel." nil
-  (erc-display-message parsed '(notice error) 'active
+  (erc-display-message parsed 'error 'active
                        's404 ?c (cadr (erc-response.command-args parsed))))
 
 
 (define-erc-response-handler (405)
   "Can't join that many channels." nil
-  (erc-display-message parsed '(notice error) 'active
+  (erc-display-message parsed 'error 'active
                        's405 ?c (cadr (erc-response.command-args parsed))))
 
 (define-erc-response-handler (406)
   "No such nick." nil
-  (erc-display-message parsed '(notice error) 'active
+  (erc-display-message parsed 'error 'active
                        's406 ?n (cadr (erc-response.command-args parsed))))
 
 (define-erc-response-handler (412)
   "No text to send." nil
-  (erc-display-message parsed '(notice error) 'active 's412))
+  (erc-display-message parsed 'error 'active 's412))
 
 (define-erc-response-handler (421)
   "Unknown command." nil
-  (erc-display-message parsed '(notice error) 'active 's421
+  (erc-display-message parsed 'error 'active 's421
                        ?c (cadr (erc-response.command-args parsed))))
 
 (define-erc-response-handler (432)
   "Bad nick." nil
-  (erc-display-message parsed '(notice error) 'active 's432
+  (erc-display-message parsed 'error 'active 's432
                        ?n (cadr (erc-response.command-args parsed))))
 
 (define-erc-response-handler (433)
@@ -2469,12 +2468,12 @@ erc-server-322-message
 
 (define-erc-response-handler (442)
   "Not on channel." nil
-  (erc-display-message parsed '(notice error) 'active 's442
+  (erc-display-message parsed 'error 'active 's442
                        ?c (cadr (erc-response.command-args parsed))))
 
 (define-erc-response-handler (461)
   "Not enough parameters for command." nil
-  (erc-display-message parsed '(notice error)  'active 's461
+  (erc-display-message parsed 'error 'active 's461
                        ?c (cadr (erc-response.command-args parsed))
                        ?m (erc-response.contents parsed)))
 
@@ -2482,20 +2481,19 @@ erc-server-322-message
   "You are banned from this server." nil
   (setq erc-server-banned t)
   ;; show the server's message, as a reason might be provided
-  (erc-display-error-notice
-   parsed
+  (erc-display-message parsed 'error 'active
    (erc-response.contents parsed)))
 
 (define-erc-response-handler (474)
   "Banned from channel errors." nil
-  (erc-display-message parsed '(notice error) nil
+  (erc-display-message parsed 'error nil
                        (intern (format "s%s"
                                        (erc-response.command parsed)))
                        ?c (cadr (erc-response.command-args parsed))))
 
 (define-erc-response-handler (475)
   "Channel key needed." nil
-  (erc-display-message parsed '(notice error) nil 's475
+  (erc-display-message parsed 'error nil 's475
                        ?c (cadr (erc-response.command-args parsed)))
   (when erc-prompt-for-channel-key
     (let ((channel (cadr (erc-response.command-args parsed)))
@@ -2516,7 +2514,7 @@ erc-server-322-message
   "You need to be a channel operator to do that." nil
   (let ((channel (cadr (erc-response.command-args parsed)))
         (message (erc-response.contents parsed)))
-    (erc-display-message parsed '(notice error) 'active 's482
+    (erc-display-message parsed 'error 'active 's482
                          ?c channel ?m message)))
 
 (define-erc-response-handler (671)
@@ -2551,11 +2549,8 @@ erc-server-322-message
   ;; 491 - No O-lines for your host
   ;; 501 - Unknown MODE flag
   ;; 502 - Cannot change mode for other users
-  "Generic display of server error messages.
-
-See `erc-display-error-notice'." nil
-  (erc-display-error-notice
-   parsed
+  "Display error message as given from server." nil
+  (erc-display-message parsed 'error 'active
    (intern (format "s%s" (erc-response.command parsed)))))
 
 ;; FIXME: These are yet to be implemented, they're just stubs for now
diff --git a/lisp/erc/erc-button.el b/lisp/erc/erc-button.el
index 0c616a6026d..c30f7c10ca6 100644
--- a/lisp/erc/erc-button.el
+++ b/lisp/erc/erc-button.el
@@ -355,8 +355,6 @@ erc-button--nick
   ( cuser nil :type (or null erc-channel-user)
     ;; The CDR of a value from an `erc-channel-users' table.
     :documentation "A possibly nil `erc-channel-user'.")
-  ( face erc-button-face :type symbol
-    :documentation "Temp `erc-button-face' while buttonizing.")
   ( nickname-face erc-button-nickname-face :type symbol
     :documentation "Temp `erc-button-nickname-face' while buttonizing.")
   ( mouse-face erc-button-mouse-face :type symbol
@@ -431,45 +429,43 @@ erc-button--phantom-users-mode
 
 (defun erc-button-add-nickname-buttons (entry)
   "Search through the buffer for nicknames, and add buttons."
-  (let ((form (nth 2 entry))
-        (fun (nth 3 entry))
-        (erc-button-buttonize-nicks (and erc-button-buttonize-nicks
-                                         erc-button--modify-nick-function))
-        bounds word)
-    (when (and form (setq form (erc-button--extract-form form)))
-      (goto-char (point-min))
-      (while (erc-forward-word)
-        (when (setq bounds (erc-bounds-of-word-at-point))
-          (setq word (buffer-substring-no-properties
-                      (car bounds) (cdr bounds)))
-          (let* ((erc-button-face erc-button-face)
-                 (erc-button-mouse-face erc-button-mouse-face)
-                 (erc-button-nickname-face erc-button-nickname-face)
-                 (down (erc-downcase word))
-                 (cuser (and erc-channel-users
-                             (gethash down erc-channel-users)))
-                 (user (or (and cuser (car cuser))
-                           (and erc-server-users
-                                (gethash down erc-server-users))
-                           (funcall erc-button--fallback-user-function
-                                    down word bounds)))
-                 (data (list word)))
-            (when (or (not (functionp form))
-                      (and-let* ((user)
-                                 (obj (funcall form (make-erc-button--nick
-                                                     :bounds bounds :data data
-                                                     :downcased down :user user
-                                                     :cuser (cdr cuser)))))
-                        (setq bounds (erc-button--nick-bounds obj)
-                              data (erc-button--nick-data obj)
-                              erc-button-mouse-face
-                              (erc-button--nick-mouse-face obj)
-                              erc-button-nickname-face
-                              (erc-button--nick-nickname-face obj)
-                              erc-button-face
-                              (erc-button--nick-face obj))))
-              (erc-button-add-button (car bounds) (cdr bounds)
-                                     fun t data))))))))
+  (when-let ((form (nth 2 entry))
+             ;; Spoof `form' slot of default legacy `nicknames' entry
+             ;; so `erc-button--extract-form' sees a function value.
+             (form (let ((erc-button-buttonize-nicks
+                          (and erc-button-buttonize-nicks
+                               erc-button--modify-nick-function)))
+                     (erc-button--extract-form form)))
+             (seen 0))
+    (goto-char (point-min))
+    (while-let
+        (((erc-forward-word))
+         (bounds (or (and (= 1 (cl-incf seen)) (erc--get-speaker-bounds))
+                     (erc-bounds-of-word-at-point)))
+         (word (buffer-substring-no-properties (car bounds) (cdr bounds)))
+         (down (erc-downcase word)))
+      (let* ((erc-button-mouse-face erc-button-mouse-face)
+             (erc-button-nickname-face erc-button-nickname-face)
+             (cuser (and erc-channel-users (gethash down erc-channel-users)))
+             (user (or (and cuser (car cuser))
+                       (and erc-server-users (gethash down erc-server-users))
+                       (funcall erc-button--fallback-user-function
+                                down word bounds)))
+             (data (list word)))
+        (when (or (not (functionp form))
+                  (and-let* ((user)
+                             (obj (funcall form (make-erc-button--nick
+                                                 :bounds bounds :data data
+                                                 :downcased down :user user
+                                                 :cuser (cdr cuser)))))
+                    (setq erc-button-mouse-face ; might be null
+                          (erc-button--nick-mouse-face obj)
+                          erc-button-nickname-face ; might be null
+                          (erc-button--nick-nickname-face obj)
+                          data (erc-button--nick-data obj)
+                          bounds (erc-button--nick-bounds obj))))
+          (erc-button-add-button (car bounds) (cdr bounds) (nth 3 entry)
+                                 'nickp data))))))
 
 (defun erc-button-add-buttons-1 (regexp entry)
   "Search through the buffer for matches to ENTRY and add buttons."
diff --git a/lisp/erc/erc-dcc.el b/lisp/erc/erc-dcc.el
index cc2dcc9a788..8968295a83c 100644
--- a/lisp/erc/erc-dcc.el
+++ b/lisp/erc/erc-dcc.el
@@ -566,7 +566,7 @@ erc-dcc-do-GET-command
                                           file))
                      (erc-dcc-get-file elt file proc)
                    (erc-display-message
-                    nil '(notice error) proc
+                    nil 'error proc
                     'dcc-get-cmd-aborted
                     ?n nick ?f filename)))
                 (t
@@ -578,7 +578,7 @@ erc-dcc-do-GET-command
             (setq erc-dcc-list (cons (plist-put elt :turbo t)
                                      (delq elt erc-dcc-list)))))
       (erc-display-message
-       nil '(notice error) 'active
+       nil 'error 'active
        'dcc-get-notfound ?n nick ?f filename))))
 
 (defvar-local erc-dcc-byte-count nil)
@@ -648,7 +648,7 @@ erc-dcc-do-SEND-command
          nil 'notice 'active
          'dcc-send-offer ?n nick ?f file)
         (erc-dcc-send-file nick file) t)
-    (erc-display-message nil '(notice error) proc "File not found") t))
+    (erc-display-message nil 'error proc "File not found") t))
 
 ;;; Server message handling (i.e. messages from remote users)
 
@@ -675,7 +675,7 @@ erc-ctcp-query-DCC
         (funcall handler proc query nick login host to)
       ;; FIXME: Send a ctcp error notice to the remote end?
       (erc-display-message
-       nil '(notice error) proc
+       nil 'error proc
        'dcc-ctcp-unknown
        ?q query ?n nick ?u login ?h host))))
 
@@ -771,7 +771,7 @@ erc-dcc-handle-ctcp-chat
      (;; DCC CHAT requests must be sent to you, and you alone.
       (not (erc-current-nick-p to))
       (erc-display-message
-       nil '(notice error) proc
+       nil 'error proc
        'dcc-request-bogus ?r "CHAT" ?n nick ?u login ?h host))
      ((string-match erc-dcc-ctcp-query-chat-regexp query)
       ;; We need to use let* here, since erc-dcc-member might clutter
@@ -805,7 +805,7 @@ erc-dcc-handle-ctcp-chat
                                  proc))))
      (t
       (erc-display-message
-       nil '(notice error) proc
+       nil 'error proc
        'dcc-malformed ?n nick ?u login ?h host ?q query)))))
 
 
@@ -1053,7 +1053,7 @@ erc-dcc-get-filter
        ((and (> (plist-get erc-dcc-entry-data :size) 0)
              (> received-bytes (plist-get erc-dcc-entry-data :size)))
         (erc-display-message
-         nil '(notice error) 'active
+         nil 'error 'active
          'dcc-get-file-too-long
          ?f (file-name-nondirectory (buffer-name)))
         (delete-process proc))
@@ -1085,7 +1085,7 @@ erc-dcc-get-sentinel
       (erc-dcc-append-contents (current-buffer) erc-dcc-file-name))
     (let ((done (= erc-dcc-byte-count (plist-get erc-dcc-entry-data :size))))
       (erc-display-message
-       nil (if done 'notice '(notice error)) erc-server-process
+       nil (if done 'notice 'error) erc-server-process
        (if done 'dcc-get-complete 'dcc-get-failed)
        ?v (plist-get erc-dcc-entry-data :size)
        ?f erc-dcc-file-name
diff --git a/lisp/erc/erc-fill.el b/lisp/erc/erc-fill.el
index 35289910d0a..a65c95f1d85 100644
--- a/lisp/erc/erc-fill.el
+++ b/lisp/erc/erc-fill.el
@@ -124,11 +124,9 @@ erc-fill-line-spacing
   :package-version '(ERC . "5.6") ; FIXME sync on release
   :type '(choice (const nil) number))
 
-(defcustom erc-fill-spaced-commands '(PRIVMSG NOTICE)
+(defvar erc-fill--spaced-commands '(PRIVMSG NOTICE)
   "Types of messages to add space between on graphical displays.
-Only considered when `erc-fill-line-spacing' is non-nil."
-  :package-version '(ERC . "5.6") ; FIXME sync on release
-  :type '(repeat (choice integer symbol)))
+Only considered when `erc-fill-line-spacing' is non-nil.")
 
 (defvar-local erc-fill--function nil
   "Internal copy of `erc-fill-function'.
@@ -153,12 +151,12 @@ erc-fill
                       (p (point-min)))
             (widen)
             (when (or (and-let* ((cmd (get-text-property p 'erc-command)))
-                        (memq cmd erc-fill-spaced-commands))
+                        (memq cmd erc-fill--spaced-commands))
                       (and-let* ((cmd (save-excursion
                                         (forward-line -1)
                                         (get-text-property (point)
                                                            'erc-command))))
-                        (memq cmd erc-fill-spaced-commands)))
+                        (memq cmd erc-fill--spaced-commands)))
               (put-text-property (1- p) p
                                  'line-spacing erc-fill-line-spacing))))))))
 
@@ -433,13 +431,8 @@ erc-fill-wrap
     (let ((len (or (and erc-fill--wrap-length-function
                         (funcall erc-fill--wrap-length-function))
                    (progn
-                     (when-let ((b (next-single-property-change
-                                    (point) 'erc-speaker nil (pos-eol)))
-                                ((/= (pos-eol) b))
-                                ;; String vals `eq' along same stretch
-                                (e (text-property-not-all
-                                    b (pos-eol) 'erc-speaker
-                                    (get-text-property b 'erc-speaker)))
+                     (when-let ((e (erc--get-speaker-bounds))
+                                (b (pop e))
                                 ((or erc-fill--wrap-action-dedent-p
                                      (not (eq (get-text-property b 'erc-ctcp)
                                               'ACTION)))))
diff --git a/lisp/erc/erc-match.el b/lisp/erc/erc-match.el
index 2b7fff87ff0..549de4feeb8 100644
--- a/lisp/erc/erc-match.el
+++ b/lisp/erc/erc-match.el
@@ -657,22 +657,18 @@ erc-go-to-log-matches-buffer
 
 (defvar-local erc-match--hide-fools-offset-bounds nil)
 
-;; FIXME this should merge with instead of overwrite existing
-;; `invisible' values.
 (defun erc-hide-fools (match-type _nickuserhost _message)
- "Hide foolish comments.
-This function should be called from `erc-text-matched-hook'."
+  "Hide comments from designated fools."
   (when (eq match-type 'fool)
     (if erc-match--hide-fools-offset-bounds
         (let ((beg (point-min))
               (end (point-max)))
           (save-restriction
             (widen)
-            (put-text-property (1- beg) (1- end) 'invisible 'erc-match)))
-      ;; The docs say `intangible' is deprecated, but this has been
-      ;; like this for ages.  Should verify unneeded and remove if so.
-      (erc-put-text-properties (point-min) (point-max)
-                               '(invisible intangible)))))
+            (erc--merge-prop (1- beg) (1- end) 'invisible 'erc-match)))
+      ;; Before ERC 5.6, this also used to add an `intangible'
+      ;; property, but the docs say it's now obsolete.
+      (erc--merge-prop (point-min) (point-max) 'invisible 'erc-match))))
 
 (defun erc-beep-on-match (match-type _nickuserhost _message)
   "Beep when text matches.
diff --git a/lisp/erc/erc-networks.el b/lisp/erc/erc-networks.el
index 482d6d901ab..dd481032e7e 100644
--- a/lisp/erc/erc-networks.el
+++ b/lisp/erc/erc-networks.el
@@ -29,6 +29,8 @@
 ;;
 ;; This is the "networks" module.
 ;;
+;; M-x erc-server-select provides an alternative way to connect to servers by
+;; choosing networks.
 ;; You can use (eq (erc-network) 'Network) if you'd like to set variables or do
 ;; certain actions according to which network you're connected to.
 ;; If a network you use is not listed in `erc-networks-alist', you can put
@@ -485,8 +487,6 @@ erc-server-alist
 				       (choice (integer :tag "Port number")
 					       (list :tag "Port range"
 						     integer integer)))))))
-(make-obsolete-variable 'erc-server-alist
-                        "specify `:server' with `erc-tls'." "30.1")
 
 (defcustom erc-networks-alist
   '((4-irc "4-irc.com")
@@ -1544,9 +1544,9 @@ erc-ports-list
 				 result)))))
     (nreverse result)))
 
+;;;###autoload
 (defun erc-server-select ()
   "Interactively select a server to connect to using `erc-server-alist'."
-  (declare (obsolete erc-tls "30.1"))
   (interactive)
   (let* ((completion-ignore-case t)
 	 (net (intern
diff --git a/lisp/erc/erc-sasl.el b/lisp/erc/erc-sasl.el
index c6922b1b26b..73d318fd4fd 100644
--- a/lisp/erc/erc-sasl.el
+++ b/lisp/erc/erc-sasl.el
@@ -377,7 +377,7 @@ erc-sasl--destroy
 
 (define-erc-response-handler (902)
   "Handle an ERR_NICKLOCKED response." nil
-  (erc-display-message parsed '(notice error) 'active 's902
+  (erc-display-message parsed 'error 'active 's902
                        ?n (car (erc-response.command-args parsed))
                        ?s (erc-response.contents parsed))
   (erc-sasl--destroy proc))
@@ -391,19 +391,19 @@ erc-sasl--destroy
 
 (define-erc-response-handler (907)
   "Handle a RPL_SASLALREADY response." nil
-  (erc-display-message parsed '(notice error) 'active 's907
+  (erc-display-message parsed 'error 'active 's907
                        ?s (erc-response.contents parsed)))
 
 (define-erc-response-handler (904 905 906)
   "Handle various SASL-related error responses." nil
-  (erc-display-message parsed '(notice error) 'active
+  (erc-display-message parsed 'error 'active
                        (intern (format "s%s" (erc-response.command parsed)))
                        ?s (erc-response.contents parsed))
   (erc-sasl--destroy proc))
 
 (define-erc-response-handler (908)
   "Handle a RPL_SASLMECHS response." nil
-  (erc-display-message parsed '(notice error) 'active 's908
+  (erc-display-message parsed 'error 'active 's908
                        ?m (alist-get 'mechanism erc-sasl--options)
                        ?s (string-join (cdr (erc-response.command-args parsed))
                                        " "))
diff --git a/lisp/erc/erc-stamp.el b/lisp/erc/erc-stamp.el
index 5035e60a87d..2f52d78d42b 100644
--- a/lisp/erc/erc-stamp.el
+++ b/lisp/erc/erc-stamp.el
@@ -179,6 +179,12 @@ stamp
      (kill-local-variable 'erc-timestamp-last-inserted-left)
      (kill-local-variable 'erc-timestamp-last-inserted-right))))
 
+(defvar erc-stamp--invisible-property nil
+  "Existing `invisible' property value and/or symbol `timestamp'.")
+
+(defvar erc-stamp--skip-when-invisible nil
+  "Escape hatch for omitting stamps when first char is invisible.")
+
 (defun erc-stamp--recover-on-reconnect ()
   (when-let ((priors (or erc--server-reconnecting erc--target-priors)))
     (dolist (var '(erc-timestamp-last-inserted
@@ -209,8 +215,11 @@ erc-add-timestamp
   (progn ; remove this `progn' on next major refactor
     (let* ((ct (erc-stamp--current-time))
            (invisible (get-text-property (point-min) 'invisible))
+           (erc-stamp--invisible-property
+            ;; FIXME on major version bump, make this `erc-' prefixed.
+            (if invisible `(timestamp ,@(ensure-list invisible)) 'timestamp))
            (erc-stamp--current-time ct))
-      (unless invisible
+      (unless (setq invisible (and erc-stamp--skip-when-invisible invisible))
         (funcall erc-insert-timestamp-function
                  (erc-format-timestamp ct erc-timestamp-format)))
       ;; FIXME this will error when advice has been applied.
@@ -380,7 +389,7 @@ erc-insert-timestamp-left
 	 (s (if ignore-p (make-string len ? ) string)))
     (unless ignore-p (setq erc-timestamp-last-inserted string))
     (erc-put-text-property 0 len 'field 'erc-timestamp s)
-    (erc-put-text-property 0 len 'invisible 'timestamp s)
+    (erc-put-text-property 0 len 'invisible erc-stamp--invisible-property s)
     (insert s)))
 
 (defun erc-insert-aligned (string pos)
@@ -477,6 +486,8 @@ erc-insert-timestamp-right
           (put-text-property from (point) p v)))
       (erc-put-text-property from (point) 'field 'erc-timestamp)
       (erc-put-text-property from (point) 'rear-nonsticky t)
+      (erc-put-text-property from (point) 'invisible
+                             erc-stamp--invisible-property)
       (when erc-timestamp-intangible
 	(erc-put-text-property from (1+ (point)) 'cursor-intangible t)))))
 
@@ -520,9 +531,8 @@ erc-format-timestamp
       (let ((ts (format-time-string format time erc-stamp--tz)))
 	(erc-put-text-property 0 (length ts)
 			       'font-lock-face 'erc-timestamp-face ts)
-	(erc-put-text-property 0 (length ts) 'invisible 'timestamp ts)
-	(erc-put-text-property 0 (length ts)
-			       'isearch-open-invisible 'timestamp ts)
+        (erc-put-text-property 0 (length ts) 'invisible
+                               erc-stamp--invisible-property ts)
 	;; N.B. Later use categories instead of this harmless, but
 	;; inelegant, hack. -- BPT
 	(and erc-timestamp-intangible
diff --git a/lisp/erc/erc-track.el b/lisp/erc/erc-track.el
index ef064c6a4ee..bc09c5d87fb 100644
--- a/lisp/erc/erc-track.el
+++ b/lisp/erc/erc-track.el
@@ -164,7 +164,6 @@ erc-track-use-faces
 
 (defcustom erc-track-faces-priority-list
   '(erc-error-face
-    (erc-error-face erc-notice-face)
     (erc-nick-default-face erc-current-nick-face)
     erc-current-nick-face
     erc-keyword-face
@@ -311,6 +310,8 @@ erc-track-switch-direction
 		 (const leastactive)
 		 (const mostactive)))
 
+(defconst erc-track--attn-faces '((erc-error-face erc-notice-face))
+  "Faces whose presence always trigger mode-line inclusion.")
 
 (defun erc-track-remove-from-mode-line ()
   "Remove `erc-track-modified-channels' from the mode-line."
@@ -738,6 +739,9 @@ erc-track-find-face
   (declare (obsolete erc-track-select-mode-line-face "28.1"))
   (erc-track-select-mode-line-face (car faces) (cdr faces)))
 
+;; Note that unless called by `erc-track-modified-channels',
+;; `erc-track-faces-priority-list' will not begin with
+;; `erc-track--attn-faces'.
 (defun erc-track-select-mode-line-face (cur-face new-faces)
   "Return the face to use in the mode line.
 
@@ -804,7 +808,9 @@ erc-track-modified-channels
 	;; (in the car), change its face attribute (in the cddr) if
 	;; necessary.  See `erc-modified-channels-alist' for the
 	;; exact data structure used.
-	(let ((faces (erc-faces-in (buffer-string))))
+        (let ((faces (erc-faces-in (buffer-string)))
+              (erc-track-faces-priority-list
+               `(,@erc-track--attn-faces ,@erc-track-faces-priority-list)))
 	  (unless (and
 		   (or (eq erc-track-priority-faces-only 'all)
 		       (member this-channel erc-track-priority-faces-only))
@@ -875,7 +881,7 @@ erc-track-face-priority
 higher number than any other face in that list."
   (let ((count 0))
     (catch 'done
-      (dolist (item erc-track-faces-priority-list)
+      (dolist (item `(,@erc-track--attn-faces ,@erc-track-faces-priority-list))
 	(if (equal item face)
 	    (throw 'done t)
 	  (setq count (1+ count)))))
diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index a7d3f7d0ed5..98127697815 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -1309,7 +1309,8 @@ erc-notice-face
   "ERC face for notices."
   :group 'erc-faces)
 
-(defface erc-action-face '((t :weight bold))
+(defface erc-action-face '((((supports :weight semi-bold)) :weight semi-bold)
+                           (t :weight bold))
   "ERC face for actions generated by /ME."
   :group 'erc-faces)
 
@@ -4962,17 +4963,14 @@ erc--nickname-in-use-make-request
   (erc-cmd-NICK temp))
 
 (defun erc-nickname-in-use (nick reason)
-  "If NICK is unavailable, tell the user the REASON.
-
-See also `erc-display-error-notice'."
+  "Explain REASON NICK is taken and maybe ask for alternate."
   (if (or (not erc-try-new-nick-p)
           ;; how many default-nicks are left + one more try...
           (eq erc-nick-change-attempt-count
               (if (consp erc-nick)
                   (+ (length erc-nick) 1)
                 1)))
-      (erc-display-error-notice
-       nil
+      (erc-display-message nil 'error 'active
        (format "Nickname %s is %s, try another." nick reason))
     (setq erc-nick-change-attempt-count (+ erc-nick-change-attempt-count 1))
     (let ((newnick (nth 1 erc-default-nicks))
@@ -4995,8 +4993,7 @@ erc-nickname-in-use
                                    (- 9 (length erc-nick-uniquifier))))
 				erc-nick-uniquifier)))
       (erc--nickname-in-use-make-request nick newnick)
-      (erc-display-error-notice
-       nil
+      (erc-display-message nil 'error 'active
        (format "Nickname %s is %s, trying %s"
                nick reason newnick)))))
 
@@ -5052,6 +5049,16 @@ erc-is-message-ctcp-and-not-action-p
   (and (erc-is-message-ctcp-p message)
        (not (string-match "^\C-aACTION.*\C-a$" message))))
 
+(define-inline erc--get-speaker-bounds ()
+  "Return the bounds of `erc-speaker' property when present.
+Assume buffer is narrowed to the confines of an inserted message."
+  (inline-quote
+   (and-let*
+       (((memq (get-text-property (point) 'erc-command) '(PRIVMSG NOTICE)))
+        (beg (or (and (get-text-property (point-min) 'erc-speaker) (point-min))
+                 (next-single-property-change (point-min) 'erc-speaker))))
+     (cons beg (next-single-property-change beg 'erc-speaker)))))
+
 (defvar erc--user-from-nick-function #'erc--examine-nick
   "Function to possibly consider unknown user.
 Must return either nil or a cons of an `erc-server-user' and a
@@ -5069,8 +5076,9 @@ erc-format-privmessage
          (str    (format "%s%s%s %s" mark-s nick mark-e msg))
          (nick-face (if privp 'erc-nick-msg-face 'erc-nick-default-face))
          (nick-prefix-face (get-text-property 0 'font-lock-face nick))
-         (prefix-len (or (text-property-not-all 0 (length nick) 'font-lock-face
-                                                nick-prefix-face nick)
+         (prefix-len (or (and nick-prefix-face (text-property-not-all
+                                                0 (length nick) 'font-lock-face
+                                                nick-prefix-face nick))
                          0))
          (msg-face (if privp 'erc-direct-msg-face 'erc-default-face)))
     ;; add text properties to text before the nick, the nick and after the nick
diff --git a/test/lisp/erc/erc-fill-tests.el b/test/lisp/erc/erc-fill-tests.el
index 15a8087f848..99ec4a9635e 100644
--- a/test/lisp/erc/erc-fill-tests.el
+++ b/test/lisp/erc/erc-fill-tests.el
@@ -153,7 +153,10 @@ erc-fill-tests--compare
         (with-temp-file expect-file
           (insert repr))
       (if (file-exists-p expect-file)
-          ;; Compare set-equal over intervals
+          ;; Compare set-equal over intervals.  This comparison is
+          ;; less useful for messages treated by other modules because
+          ;; it doesn't compare "nested" props belonging to
+          ;; string-valued properties, like timestamps.
           (should (equal-including-properties
                    (read repr)
                    (read (with-temp-buffer
diff --git a/test/lisp/erc/erc-scenarios-match.el b/test/lisp/erc/erc-scenarios-match.el
index 782907bfc30..edc1749cdd2 100644
--- a/test/lisp/erc/erc-scenarios-match.el
+++ b/test/lisp/erc/erc-scenarios-match.el
@@ -26,6 +26,7 @@
 
 (require 'erc-stamp)
 (require 'erc-match)
+(require 'erc-fill)
 
 ;; This defends against a regression in which all matching by the
 ;; `erc-match-message' fails when `erc-add-timestamp' precedes it in
@@ -57,28 +58,20 @@ erc-scenarios-match--stamp-left-current-nick
         (should (eq (get-text-property (1- (point)) 'font-lock-face)
                     'erc-current-nick-face))))))
 
-;; This asserts that when stamps appear before a message,
-;; some non-nil invisibility property spans the entire message.
-(ert-deftest erc-scenarios-match--stamp-left-fools-invisible ()
-  :tags '(:expensive-test)
-  (ert-skip "WIP: fix included in bug#64301")
+;; When hacking on tests that use this fixture, it's best to run it
+;; interactively, and check for wierdness before and after doing
+;; M-: (remove-from-invisibility-spec 'erc-match) RET.
+(defun erc-scenarios-match--invisible-stamp (hiddenp visiblep)
   (erc-scenarios-common-with-cleanup
       ((erc-scenarios-common-dialog "join/legacy")
        (dumb-server (erc-d-run "localhost" t 'foonet))
        (port (process-contact dumb-server :service))
        (erc-server-flood-penalty 0.1)
-       (erc-insert-timestamp-function 'erc-insert-timestamp-left)
        (erc-timestamp-only-if-changed-flag nil)
        (erc-fools '("bob"))
        (erc-text-matched-hook '(erc-hide-fools))
        (erc-autojoin-channels-alist '((FooNet "#chan")))
-       (expect (erc-d-t-make-expecter))
-       (hiddenp (lambda ()
-                  (and (eq (field-at-pos (pos-bol)) 'erc-timestamp)
-                       (get-text-property (pos-bol) 'invisible)
-                       (>= (next-single-property-change (pos-bol)
-                                                        'invisible nil)
-                           (pos-eol))))))
+       (expect (erc-d-t-make-expecter)))
 
     (ert-info ("Connect")
       (with-current-buffer (erc :server "127.0.0.1"
@@ -94,30 +87,155 @@ erc-scenarios-match--stamp-left-fools-invisible
     (ert-info ("Ensure lines featuring \"bob\" are invisible")
       (with-current-buffer (erc-d-t-wait-for 10 (get-buffer "#chan"))
         (should (funcall expect 10 "<bob> tester, welcome!"))
-        (should (funcall hiddenp))
+        (ert-info ("<bob> tester, welcome!") (funcall hiddenp))
 
         ;; Alice's is the only one visible.
         (should (funcall expect 10 "<alice> tester, welcome!"))
-        (should (eq (field-at-pos (pos-bol)) 'erc-timestamp))
-        (should (get-text-property (pos-bol) 'invisible))
-        (should-not (get-text-property (point) 'invisible))
+        (ert-info ("<alice> tester, welcome!") (funcall visiblep))
 
         (should (funcall expect 10 "<bob> alice: But, as it seems"))
-        (should (funcall hiddenp))
+        (ert-info ("<bob> alice: But, as it seems") (funcall hiddenp))
 
         (should (funcall expect 10 "<alice> bob: Well, this is the forest"))
-        (should (funcall hiddenp))
+        (ert-info ("<alice> bob: Well, this is the forest") (funcall hiddenp))
 
         (should (funcall expect 10 "<alice> bob: And will you"))
-        (should (funcall hiddenp))
+        (ert-info ("<alice> bob: And will you") (funcall hiddenp))
 
         (should (funcall expect 10 "<bob> alice: Live, and be prosperous"))
-        (should (funcall hiddenp))
+        (ert-info ("<bob> alice: Live, and be prosperous") (funcall hiddenp))
 
         (should (funcall expect 10 "ERC>"))
         (should-not (get-text-property (pos-bol) 'invisible))
         (should-not (get-text-property (point) 'invisible))))))
 
+;; This asserts that when stamps appear before a message, registered
+;; invisibility properties owned by modules span the entire message.
+(ert-deftest erc-scenarios-match--stamp-left-fools-invisible ()
+  :tags '(:expensive-test)
+  (let ((erc-insert-timestamp-function #'erc-insert-timestamp-left))
+    (erc-scenarios-match--invisible-stamp
+
+     (lambda ()
+       ;; This is a time-stamped message.
+       (should (eq (field-at-pos (pos-bol)) 'erc-timestamp))
+
+       ;; Leading stamp has combined `invisible' property value.
+       (should (equal (get-text-property (pos-bol) 'invisible)
+                      '(timestamp erc-match)))
+
+       ;; Message proper has the `invisible' property `erc-match'.
+       (let ((msg-beg (next-single-property-change (pos-bol) 'invisible)))
+         (should (eq (get-text-property msg-beg 'invisible) 'erc-match))
+         (should (>= (next-single-property-change msg-beg 'invisible nil)
+                     (pos-eol)))))
+
+     (lambda ()
+       ;; This is a time-stamped message.
+       (should (eq (field-at-pos (pos-bol)) 'erc-timestamp))
+       (should (get-text-property (pos-bol) 'invisible))
+
+       ;; The entire message proper is visible.
+       (let ((msg-beg (next-single-property-change (pos-bol) 'invisible)))
+         (should
+          (= (next-single-property-change msg-beg 'invisible nil (pos-eol))
+             (pos-eol))))))))
+
+(defun erc-scenarios-match--find-eol ()
+  (save-excursion
+    (goto-char (next-single-property-change (point) 'erc-command))
+    (pos-eol)))
+
+;; In most cases, `erc-hide-fools' makes line endings invisible.
+(ert-deftest erc-scenarios-match--stamp-right-fools-invisible ()
+  :tags '(:expensive-test)
+  (let ((erc-insert-timestamp-function #'erc-insert-timestamp-right))
+    (erc-scenarios-match--invisible-stamp
+
+     (lambda ()
+       (let ((end (erc-scenarios-match--find-eol)))
+         ;; The end of the message is a newline.
+         (should (= ?\n (char-after end)))
+
+         ;; Every message has a trailing time stamp.
+         (should (eq (field-at-pos (1- end)) 'erc-timestamp))
+
+         ;; Stamps have a combined `invisible' property value.
+         (should (equal (get-text-property (1- end) 'invisible)
+                        '(timestamp erc-match)))
+
+         ;; The final newline is hidden by `match', not `stamps'
+         (should (equal (get-text-property end 'invisible) 'erc-match))
+
+         ;; The message proper has the `invisible' property `erc-match',
+         ;; and it starts after the preceding newline.
+         (should (eq (get-text-property (pos-bol) 'invisible) 'erc-match))
+
+         ;; It ends just before the timestamp.
+         (let ((msg-end (next-single-property-change (pos-bol) 'invisible)))
+           (should (equal (get-text-property msg-end 'invisible)
+                          '(timestamp erc-match)))
+
+           ;; Stamp's `invisible' property extends throughout the stamp
+           ;; and ends before the trailing newline.
+           (should (= (next-single-property-change msg-end 'invisible) end)))))
+
+     (lambda ()
+       (let ((end (erc-scenarios-match--find-eol)))
+         ;; This message has a time stamp like all the others.
+         (should (eq (field-at-pos (1- end)) 'erc-timestamp))
+
+         ;; The entire message proper is visible.
+         (should-not (get-text-property (pos-bol) 'invisible))
+         (let ((inv-beg (next-single-property-change (pos-bol) 'invisible)))
+           (should (eq (get-text-property inv-beg 'invisible)
+                       'timestamp))))))))
+
+;; This asserts that when `erc-fill-wrap-mode' is enabled, ERC hides
+;; the preceding message's line ending.
+(ert-deftest erc-scenarios-match--stamp-right-invisible-fill-wrap ()
+  :tags '(:expensive-test)
+  (let ((erc-insert-timestamp-function #'erc-insert-timestamp-right)
+        (erc-fill-function #'erc-fill-wrap))
+    (erc-scenarios-match--invisible-stamp
+
+     (lambda ()
+       ;; Every message has a trailing time stamp.
+       (should (eq (field-at-pos (1- (pos-eol))) 'erc-timestamp))
+
+       ;; Stamps appear in the right margin.
+       (should (equal (car (get-text-property (1- (pos-eol)) 'display))
+                      '(margin right-margin)))
+
+       ;; Stamps have a combined `invisible' property value.
+       (should (equal (get-text-property (1- (pos-eol)) 'invisible)
+                      '(timestamp erc-match)))
+
+       ;; The message proper has the `invisible' property `erc-match',
+       ;; which starts at the preceding newline...
+       (should (eq (get-text-property (1- (pos-bol)) 'invisible) 'erc-match))
+
+       ;; ... and ends just before the timestamp.
+       (let ((msgend (next-single-property-change (1- (pos-bol)) 'invisible)))
+         (should (equal (get-text-property msgend 'invisible)
+                        '(timestamp erc-match)))
+
+         ;; The newline before `erc-insert-marker' is still visible.
+         (should-not (get-text-property (pos-eol) 'invisible))
+         (should (= (next-single-property-change msgend 'invisible)
+                    (pos-eol)))))
+
+     (lambda ()
+       ;; This message has a time stamp like all the others.
+       (should (eq (field-at-pos (1- (pos-eol))) 'erc-timestamp))
+
+       ;; Unlike hidden messages, the preceding newline is visible.
+       (should-not (get-text-property (1- (pos-bol)) 'invisible))
+
+       ;; The entire message proper is visible.
+       (let ((inv-beg (next-single-property-change (1- (pos-bol)) 'invisible)))
+         (should (eq (get-text-property inv-beg 'invisible) 'timestamp)))))))
+
 (eval-when-compile (require 'erc-join))
 
 ;;; erc-scenarios-match.el ends here
-- 
2.41.0