Skip erc-ignored-user-p when erc-ignore-list is empty

* lisp/erc/erc-backend.el (erc-server-PRIVMSG): Don't bother running
`erc-ignored-user-p' and `erc-ignored-reply-p' when their associated
options are null.  The option `erc-ignore-list' is buffer-local when
set, and `erc-ignored-user-p' looks for it in the server buffer.
Moreover, all functions that set it, like `erc-cmd-IGNORE' and
`erc-cmd-UNIGNORE', do so in the server buffer.  And the response
handler in question only runs in server buffers, so this shouldn't
break anything.  Also, remove stray call to reassign trailing response
contents.
* lisp/erc/erc-common.el (erc-get-server-user): Rearrange so
`erc-with-server-buffer' doesn't have to switch to the server buffer
because `erc-downcase' can run in channels as well.
* lisp/erc/erc.el (erc-ignored-user-p): Add comment.  (Bug#67677)

3 files changed, 9 insertions, 5 deletions

diff --git a/lisp/erc/erc-backend.el b/lisp/erc/erc-backend.el
index 6483192692b..1c29f49a129 100644
--- a/lisp/erc/erc-backend.el
+++ b/lisp/erc/erc-backend.el
@@ -1913,8 +1913,10 @@ add things to `%s' instead."
         (tgt (car (erc-response.command-args parsed)))
         (msg (erc-response.contents parsed)))
     (defvar erc-minibuffer-ignored)
-    (if (or (erc-ignored-user-p sender-spec)
-            (erc-ignored-reply-p msg tgt proc))
+    (defvar erc-ignore-list)
+    (defvar erc-ignore-reply-list)
+    (if (or (and erc-ignore-list (erc-ignored-user-p sender-spec))
+            (and erc-ignore-reply-list (erc-ignored-reply-p msg tgt proc)))
         (when erc-minibuffer-ignored
           (message "Ignored %s from %s to %s" cmd sender-spec tgt))
       (let* ((sndr (erc-parse-user sender-spec))
@@ -1929,7 +1931,6 @@ add things to `%s' instead."
                                      ,@erc--display-context))
              s buffer
              fnick)
-        (setf (erc-response.contents parsed) msg)
         (setq buffer (erc-get-buffer (if privp nick tgt) proc))
         ;; Even worth checking for empty target here? (invalid anyway)
         (unless (or buffer noticep (string-empty-p tgt) (eq ?$ (aref tgt 0))
diff --git a/lisp/erc/erc-common.el b/lisp/erc/erc-common.el
index ce0831709c7..90112ab9126 100644
--- a/lisp/erc/erc-common.el
+++ b/lisp/erc/erc-common.el
@@ -498,8 +498,9 @@ Use the CASEMAPPING ISUPPORT parameter to determine the style."
 (define-inline erc-get-server-user (nick)
   "Find NICK in the current server's `erc-server-users' hash table."
   (inline-letevals (nick)
-    (inline-quote (erc-with-server-buffer
-                    (gethash (erc-downcase ,nick) erc-server-users)))))
+    (inline-quote
+     (gethash (erc-downcase ,nick)
+              (erc-with-server-buffer erc-server-users)))))
 
 (defmacro erc--with-dependent-type-match (type &rest features)
   "Massage Custom :type TYPE with :match function that pre-loads FEATURES."
diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index 2e078651a52..dad7ebab621 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -7718,6 +7718,8 @@ The previous default target of QUERY type gets removed."
         (setq erc-default-recipients d2)
       (error "Current target is not a QUERY"))))
 
+;; FIXME move all ignore-related functionality to its own module,
+;; required and enabled by default (until some major version change).
 (defun erc-ignored-user-p (spec)
   "Return non-nil if SPEC matches something in `erc-ignore-list'.