Rename erc-server-buffer-p

* lisp/erc/erc-log.el (erc-log-all-but-server-buffers): Use
`erc--server-buffer-p' instead of `erc-server-buffer-p'.  This
replacement is presumed to be relatively "safe" because this function
is unused in the code base and only appears in the doc string for the
option `erc-enable-logging'.
* lisp/erc/erc-match.el (erc-match-message): Leave comment proposing
that `erc--server-buffer-p' should be preferred to
`erc-server-buffer-p'.  Use preferred alias for `erc-server-buffer-p'.
* lisp/erc/erc-notify.el (erc-cmd-NOTIFY): Use preferred alias for
`erc-server-buffer-p', and leave FIXME comment.
* lisp/erc/erc-speedbar.el (erc-speedbar-buttons): Use
`erc--server-buffer-p' instead of `erc-server-buffer-p'.  The logic
here seems simple enough to justify a change, however the absence of
related bug reports is perhaps an argument against this.
* lisp/erc/erc-track.el (erc-track-modified-channels): Use preferred
alias for `erc-server-buffer-p' and leave comment noting possible bug.
* lisp/erc/erc.el (erc-once-with-server-event): Use
`erc--server-buffer-p' instead of `erc-server-buffer-p'.  This change
seems justified because the function sets local hooks that would
otherwise be ignored outside of a server buffer.
(erc-server-buffer-p, erc-server-or-unjoined-channel-buffer-p): Make
the former an obsolete alias for the latter.
(erc--server-buffer-p): New function to replace `erc-server-buffer-p'
internally in new code.  Unlike its predecessor, it returns nil in
parted and kicked channels.
(erc-open-server-buffer-p): Use `erc--server-buffer-p' instead of
`erc-server-buffer-p'.  Given the name and the doc string, breaking
the odd misuse of this function in parted buffers seems justified
because this is clearly a bug fix.  Also, all uses in-tree conform to
the intended behavior as documented.  And a cursory grep of all "erc-"
prefixed packages on MELPA reveals zero instances of this function.
Nor is it used in erbot.
(erc-get-buffer): Mention behavior in doc string regarding parted and
kicked-from channels.
(erc-cmd-GQUIT): Fix wrong-number-of-arguments bug in timer function.
(erc-default-target): Mention behavior regarding unjoined channels.
(erc-kill-query-buffers): Don't use `erc-server-buffer-p'.  This
replacement may break third-party code expecting to leave parted
channels behind, but it seems sane when considering only the lone
internal use in `erc-cmd-QUIT'.
; * test/lisp/erc/resources/join/network-id/foonet.eld: Timeouts.
(Bug#66578)

lisp/erc/erc-log.el

@@ -276,11 +276,11 @@ The current buffer is given by BUFFER."
 
 (defun erc-log-all-but-server-buffers (buffer)
   "Return t if logging should be enabled in BUFFER.
-Returns nil if `erc-server-buffer-p' returns t."
+Return nil if BUFFER is a server buffer."
   (save-excursion
     (save-window-excursion
       (set-buffer buffer)
-      (not (erc-server-buffer-p)))))
+      (not (erc--server-buffer-p)))))
 
 (defun erc-save-query-buffers (process)
   "Save all buffers of the given PROCESS."

lisp/erc/erc-match.el

@@ -491,7 +491,9 @@ Use this defun with `erc-insert-modify-hook'."
          (message (buffer-substring message-beg (point-max))))
     (when (and vector
 	       (not (and erc-match-exclude-server-buffer
-			 (erc-server-buffer-p))))
+                         ;; FIXME replace with `erc--server-buffer-p'
+                         ;; or explain why that's unwise.
+                         (erc-server-or-unjoined-channel-buffer-p))))
       (mapc
        (lambda (match-type)
 	 (goto-char (point-min))

lisp/erc/erc-notify.el

@@ -218,7 +218,9 @@ with args, toggle notify status of people."
 	    ;; from your notify list.
 	    (dolist (buf (erc-buffer-list))
 	      (with-current-buffer buf
-		(if (erc-server-buffer-p)
+                ;; FIXME replace with `erc--server-buffer-p' or
+                ;; explain why that's unwise.
+                (if (erc-server-or-unjoined-channel-buffer-p)
 		    (setq erc-last-ison (delete (car args) erc-last-ison))))))
 	(setq erc-notify-list (cons (erc-string-no-properties (car args))
 				    erc-notify-list)))

lisp/erc/erc-speedbar.el

@@ -135,7 +135,7 @@ This will add a speedbar major display mode."
   (erase-buffer)
   (let (serverp chanp queryp)
     (with-current-buffer buffer
-      (setq serverp (erc-server-buffer-p))
+      (setq serverp (erc--server-buffer-p))
       (setq chanp (erc-channel-p (erc-default-target)))
       (setq queryp (erc-query-buffer-p)))
     (cond (serverp

lisp/erc/erc-track.el

@@ -795,7 +795,9 @@ the current buffer is in `erc-mode'."
     (if (and (not (erc-buffer-visible (current-buffer)))
 	     (not (member this-channel erc-track-exclude))
 	     (not (and erc-track-exclude-server-buffer
-		       (erc-server-buffer-p)))
+                       ;; FIXME either use `erc--server-buffer-p' or
+                       ;; explain why that's unwise.
+                       (erc-server-or-unjoined-channel-buffer-p)))
 	     (not (erc-message-type-member
 		   (or (erc-find-parsed-property)
 		       (point-min))

lisp/erc/erc.el

@@ -1417,7 +1417,7 @@ Please be sure to use this function in server-buffers.  In
 channel-buffers it may not work at all, as it uses the LOCAL
 argument of `add-hook' and `remove-hook' to ensure multiserver
 capabilities."
-  (unless (erc-server-buffer-p)
+  (unless (erc--server-buffer-p)
     (error
      "You should only run `erc-once-with-server-event' in a server buffer"))
   (let ((fun (make-symbol "fun"))
@@ -1474,19 +1474,30 @@ the process buffer."
   (and (processp erc-server-process)
        (buffer-live-p (process-buffer erc-server-process))))
 
-(defun erc-server-buffer-p (&optional buffer)
+(define-obsolete-function-alias
+  'erc-server-buffer-p 'erc-server-or-unjoined-channel-buffer-p "30.1")
+(defun erc-server-or-unjoined-channel-buffer-p (&optional buffer)
   "Return non-nil if argument BUFFER is an ERC server buffer.
-
-If BUFFER is nil, the current buffer is used."
+If BUFFER is nil, use the current buffer.  For historical
+reasons, also return non-nil for channel buffers the client has
+parted or from which it's been kicked."
   (with-current-buffer (or buffer (current-buffer))
     (and (eq major-mode 'erc-mode)
          (null (erc-default-target)))))
 
+(defun erc--server-buffer-p (&optional buffer)
+  "Return non-nil if BUFFER is an ERC server buffer.
+Without BUFFER, use the current buffer."
+  (if buffer
+      (with-current-buffer buffer
+        (and (eq major-mode 'erc-mode) (null erc--target)))
+    (and (eq major-mode 'erc-mode) (null erc--target))))
+
 (defun erc-open-server-buffer-p (&optional buffer)
   "Return non-nil if BUFFER is an ERC server buffer with an open IRC process.
 
 If BUFFER is nil, the current buffer is used."
-  (and (erc-server-buffer-p buffer)
+  (and (erc--server-buffer-p buffer)
        (erc-server-process-alive buffer)))
 
 (defun erc-query-buffer-p (&optional buffer)
@@ -1858,7 +1869,10 @@ All strings are compared according to IRC protocol case rules, see
 
 (defun erc-get-buffer (target &optional proc)
   "Return the buffer matching TARGET in the process PROC.
-If PROC is not supplied, all processes are searched."
+Without PROC, search all ERC buffers.  For historical reasons,
+skip buffers for channels the client has \"PART\"ed or from which
+it's been \"KICK\"ed.  Expect users to use a different function
+for finding targets independent of \"JOIN\"edness."
   (let ((downcased-target (erc-downcase target)))
     (catch 'buffer
       (erc-buffer-filter
@@ -4632,10 +4646,7 @@ the message given by REASON."
     ;; kill them
     (run-at-time
      4 nil
-     (lambda ()
-       (dolist (buffer (erc-buffer-list (lambda (buf)
-                                          (not (erc-server-buffer-p buf)))))
-         (kill-buffer buffer)))))
+     #'erc-buffer-do (lambda () (when erc--target (kill-buffer)))))
   t)
 
 (defalias 'erc-cmd-GQ #'erc-cmd-GQUIT)
@@ -7075,7 +7086,9 @@ See also `erc-downcase'."
 ;; continue to use `erc-default-target'.
 
 (defun erc-default-target ()
-  "Return the current default target (as a character string) or nil if none."
+  "Return the current channel or query target, if any.
+For historical reasons, return nil in channel buffers if not
+currently joined."
   (let ((tgt (car erc-default-recipients)))
     (cond
      ((not tgt) nil)
@@ -7637,15 +7650,14 @@ If it doesn't exist, create it."
   (unless (file-attributes dir) (make-directory dir))
   (or (file-accessible-directory-p dir) (error "Cannot access %s" dir)))
 
+;; FIXME make function obsolete or alias to something less confusing.
 (defun erc-kill-query-buffers (process)
-  "Kill all buffers of PROCESS.
-Does nothing if PROCESS is not a process object."
+  "Kill all target buffers of PROCESS, including channel buffers.
+Do nothing if PROCESS is not a process object."
   ;; here, we only want to match the channel buffers, to avoid
   ;; "selecting killed buffers" b0rkage.
   (when (processp process)
-    (erc-with-all-buffers-of-server process
-      (lambda ()
-	(not (erc-server-buffer-p)))
+    (erc-with-all-buffers-of-server process (lambda () erc--target)
       (kill-buffer (current-buffer)))))
 
 (defun erc-nick-at-point ()

test/lisp/erc/resources/join/network-id/foonet.eld

@@ -1,8 +1,8 @@
 ;; -*- mode: lisp-data; -*-
 ((pass 10 "PASS :foonet:changeme"))
-((nick 1 "NICK tester"))
+((nick 10 "NICK tester"))
 
-((user 1 "USER user 0 * :tester")
+((user 10 "USER user 0 * :tester")
  (0 ":irc.foonet.org 001 tester :Welcome to the foonet IRC Network tester")
  (0 ":irc.foonet.org 002 tester :Your host is irc.foonet.org, running version oragono-2.6.0-7481bf0385b95b16")
  (0 ":irc.foonet.org 003 tester :This server was created Mon, 10 May 2021 00:58:22 UTC")