Add alias erc-buffer-do for erc-buffer-filter

* lisp/erc/erc-goodies.el (erc-scrolltobottom-enable,
erc-scrolltobottom-mode): Prefer `erc-buffer-do' to
`erc-buffer-filter'.
(erc-move-to-prompt-mode, erc-move-to-prompt-enable): Prefer
`erc-buffer-do' to `erc-buffer-filter'.
* lisp/erc/erc-imenu.el (erc-imenu-mode, erc-imenu-enable): Prefer
`erc-buffer-do' to `erc-buffer-filter'.
* lisp/erc/erc-match.el (erc-match-enable, erc-match-mode): Prefer
`erc-buffer-do' to `erc-buffer-filter'.
* lisp/erc/erc-stamp.el (erc-stamp-mode, erc-stamp-enable): Prefer
`erc-buffer-do' to `erc-buffer-filter'.
* lisp/erc/erc.el (erc-buffer-filter): Improve doc string.
(erc-buffer-do): Add alias for new code to prefer when calling
`erc-buffer-filter' for effect.  Do this because continually having to
refer back to the doc strings and implementations of the latter as
well as `erc-buffer-p', `erc-buffer-list', and co. is unproductive.
(erc-buffer-list): Use `always' as fallback predicate.

lisp/erc/erc-goodies.el

@@ -53,8 +53,7 @@ argument to `recenter'."
   "This mode causes the prompt to stay at the end of the window."
   ((add-hook 'erc-mode-hook #'erc-add-scroll-to-bottom)
    (add-hook 'erc-insert-done-hook #'erc-possibly-scroll-to-bottom)
-   (unless erc--updating-modules-p
-     (erc-buffer-filter #'erc-add-scroll-to-bottom)))
+   (unless erc--updating-modules-p (erc-buffer-do #'erc-add-scroll-to-bottom)))
   ((remove-hook 'erc-mode-hook #'erc-add-scroll-to-bottom)
    (remove-hook 'erc-insert-done-hook #'erc-possibly-scroll-to-bottom)
    (dolist (buffer (erc-buffer-list))
@@ -119,8 +118,7 @@ Put this function on `erc-insert-post-hook' and/or `erc-send-post-hook'."
 (define-erc-module move-to-prompt nil
   "This mode causes the point to be moved to the prompt when typing text."
   ((add-hook 'erc-mode-hook #'erc-move-to-prompt-setup)
-   (unless erc--updating-modules-p
-     (erc-buffer-filter #'erc-move-to-prompt-setup)))
+   (unless erc--updating-modules-p (erc-buffer-do #'erc-move-to-prompt-setup)))
   ((remove-hook 'erc-mode-hook #'erc-move-to-prompt-setup)
    (dolist (buffer (erc-buffer-list))
      (with-current-buffer buffer

lisp/erc/erc-imenu.el

@@ -139,7 +139,7 @@ Don't rely on this function, read it first!"
 (define-erc-module imenu nil
   "Simple Imenu integration for ERC."
   ((add-hook 'erc-mode-hook #'erc-imenu-setup)
-   (unless erc--updating-modules-p (erc-buffer-filter #'erc-imenu-setup)))
+   (unless erc--updating-modules-p (erc-buffer-do #'erc-imenu-setup)))
   ((remove-hook 'erc-mode-hook #'erc-imenu-setup)
    (erc-with-all-buffers-of-server nil nil
      (when erc-imenu--create-index-function

lisp/erc/erc-match.el

@@ -55,7 +55,7 @@ highlighted."
   ((add-hook 'erc-insert-modify-hook #'erc-match-message 'append)
    (add-hook 'erc-mode-hook #'erc-match--modify-invisibility-spec)
    (unless erc--updating-modules-p
-     (erc-buffer-filter #'erc-match--modify-invisibility-spec))
+     (erc-buffer-do #'erc-match--modify-invisibility-spec))
    (erc--modify-local-map t "C-c C-k" #'erc-go-to-log-matches-buffer))
   ((remove-hook 'erc-insert-modify-hook #'erc-match-message)
    (remove-hook 'erc-mode-hook #'erc-match--modify-invisibility-spec)

lisp/erc/erc-stamp.el

@@ -168,7 +168,7 @@ from entering them and instead jump over them."
    (add-hook 'erc-mode-hook #'erc-stamp--recover-on-reconnect)
    (add-hook 'erc--pre-clear-functions #'erc-stamp--reset-on-clear)
    (unless erc--updating-modules-p
-     (erc-buffer-filter #'erc-munge-invisibility-spec)))
+     (erc-buffer-do #'erc-munge-invisibility-spec)))
   ((remove-hook 'erc-mode-hook #'erc-munge-invisibility-spec)
    (remove-hook 'erc-insert-modify-hook #'erc-add-timestamp)
    (remove-hook 'erc-send-modify-hook #'erc-add-timestamp)

lisp/erc/erc.el

@@ -1830,8 +1830,9 @@ If PROC is not supplied, all processes are searched."
 
 (defun erc-buffer-filter (predicate &optional proc)
   "Return a list of `erc-mode' buffers matching certain criteria.
-PREDICATE is a function executed with each buffer, if it returns t, that buffer
-is considered a valid match.
+Call PREDICATE without arguments in all ERC buffers or only those
+belonging to a non-nil PROC.  Expect it to return non-nil in
+buffers that should be included in the returned list.
 
 PROC is either an `erc-server-process', identifying a certain
 server connection, or nil which means all open connections."
@@ -1843,15 +1844,21 @@ server connection, or nil which means all open connections."
 		 (erc--buffer-p buf predicate proc)))
              (buffer-list)))))
 
+(defalias 'erc-buffer-do 'erc-buffer-filter
+  "Call FUNCTION in all ERC buffers or only those for PROC.
+Expect users to prefer this alias to `erc-buffer-filter' in cases
+where the latter would only be called for effect and its return
+value thrown away.
+
+\(fn FUNCTION &optional PROC)")
+
 (defun erc-buffer-list (&optional predicate proc)
   "Return a list of ERC buffers.
 PREDICATE is a function which executes with every buffer satisfying
 the predicate.  If PREDICATE is passed as nil, return a list of all ERC
 buffers.  If PROC is given, the buffers local variable `erc-server-process'
 needs to match PROC."
-  (unless predicate
-    (setq predicate (lambda () t)))
-  (erc-buffer-filter predicate proc))
+  (erc-buffer-filter (or predicate #'always) proc))
 
 (define-obsolete-function-alias 'erc-iswitchb #'erc-switch-to-buffer "25.1")
 (defun erc--switch-to-buffer (&optional arg)