* lisp/gnus: Use lexical-binding in all the files

* lisp/gnus/gnus-group.el (features): Use `dlet`.
(gnus-tmp-level, gnus-tmp-marked, gnus-tmp-group): Declare vars.
(gnus-group-insert-group-line): Bind dynbound vars via `let` rather
than as formal args.  Bind `number` as dynbound.
(gnus-visual, gnus-score-find-score-files-function)
(gnus-home-score-file, gnus-apply-kill-hook)
(gnus-summary-expunge-below): Declare vars.
(gnus-group-restart, gnus-group-list-plus): Fix `interactive` spec
since the arg is unused.

* lisp/gnus/mail-source.el (mail-source-bind, mail-source-bind-common):
Use `dlet` and suppress the warnings about the non-prefixed dynbound vars.
(mail-source-set-1): Remove unused var `auth-info`.
(mail-source-call-script): Remove unused var `background`.
(mail-source-fetch-pop, mail-source-check-pop): Bind pop3 vars with `dlet`.

* lisp/gnus/gnus-int.el (mail-source-plugged, gnus-inhibit-demon):
Declare vars.
(gnus-server-opened, gnus-status-message)
(gnus-open-server, gnus-close-server, gnus-request-list)
(gnus-finish-retrieve-group-infos, gnus-retrieve-group-data-early)
(gnus-request-list-newsgroups, gnus-request-newgroups)
(gnus-request-regenerate, gnus-request-compact, gnus-request-group)
(gnus-retrieve-groups, gnus-request-post, gnus-request-expunge-group)
(gnus-request-scan, gnus-request-update-info, gnus-request-marks)
(gnus-request-accept-article, gnus-request-create-group)
(gnus-asynchronous-p, gnus-remove-denial):
Bind `gnus-command-method` via `let` rather than as formal args.

* lisp/gnus/gnus-topic.el (gnus-topic-insert-topic-line):
Pass documented vars to eval for `gnus-topic-line-format-spec`.

* lisp/gnus/message.el (message-yank-original): Use `cl-progv` rather
than `eval` to bind the vars from `message-cite-style`.

* lisp/gnus/mml.el (mml-parse-1): Use `apply` instead of `eval`.
(gnus-newsgroup-name, gnus-displaying-mime, gnus-newsgroup-name)
(gnus-article-prepare-hook, gnus-newsgroup-charset)
(gnus-original-article-buffer, gnus-message-buffer)
(message-this-is-news, message-this-is-mail): Declare vars.

* lisp/gnus/deuglify.el (gnus-outlook-rearrange-article): Remove unused
var `cite-marks`.
* lisp/gnus/gnus-art.el (ansi-color-context-region): Declare var.
(gnus-mime-display-attachment-buttons-in-header): Move declaration
before first use.
(gnus-mime-display-alternative): Remove unused var `from`.
* lisp/gnus/gnus-bookmark.el (gnus-bookmark-bmenu-list): Remove unused
var `start` `end`.
* lisp/gnus/gnus-cache.el (gnus-article-decode-hook)
(nnml-generate-active-function): Declare var.
* lisp/gnus/gnus-cite.el (gnus-message-citation-mode): Remove unused
var `keywords`.
* lisp/gnus/gnus-cloud.el (gnus-cloud-encode-data): Remove unused var
`cipher`.
(gnus-cloud-ensure-cloud-group): Remove unused var `method`.
* lisp/gnus/gnus-delay.el (gnus-delay-article): Remove unused var `days`.
* lisp/gnus/gnus-html.el (gnus-html-wash-images): Remove unused vars
`tag`, `string`, and `images`.
(gnus-html-wash-tags): Remove unused vars `string` and `images`.
* lisp/gnus/gnus-msg.el (gnus-msg-mail): Remove unused var `group-name`.
(gnus-group-mail, gnus-group-news, gnus-summary-mail-other-window)
(gnus-summary-news-other-window):
Remove unused vars `group` and `buffer`.
(gnus-configure-posting-styles): Remove unused vars `style` and `attribute`.
* lisp/gnus/gnus-picon.el (gnus-picon-find-face): Remove unused vars
`database`, `directory`, and `instance`.
(gnus-picon-transform-newsgroups): Remove unused var `point`.
* lisp/gnus/gnus-range.el (gnus-range-difference): Remove unused var `safe`.
* lisp/gnus/gnus-score.el (gnus-score-load-file): Remove unused var
`score-fn`.
* lisp/gnus/gnus-sum.el (message-options-set-recipient): Declare var.
* lisp/gnus/gnus-undo.el (gnus-undo): Fix docstring lie.
* lisp/gnus/gnus-util.el (print-string-length)
(iswitchb-make-buflist-hook): Declare vars.
(gnus-emacs-version): Remove unused var `codename`.
(gnus-rename-file): Remove unused vars `old-name` and `new-name`.
* lisp/gnus/gnus-uu.el (gnus-uu-yenc-article): Remove unused var
`start-char`.
(gnus-asynchronous): Declare var.
* lisp/gnus/mm-partial.el (gnus-displaying-mime): Declare var.
(mm-inline-partial): Remove unused var `buffer`.
* lisp/gnus/mm-view.el (w3m-force-redisplay, w3m-safe-url-regexp)
(gnus-displaying-mime, gnus-original-article-buffer)
(gnus-article-prepare-hook): Declare vars.
* lisp/gnus/mml-smime.el (mml-smime-epg-encrypt): Remove unused var
`boundary`.
(mml-smime-epg-verify): Remove unused vars `plain` and `signature-file`.
* lisp/gnus/mml1991.el (pgg-text-mode): Declare var.
* lisp/gnus/mml2015.el (pgg-text-mode): Declare var.
(mml2015-pgg-decrypt): Remove unused var `result`.
(mml2015-epg-key-image-to-string): Remove unused var `error`.
(mml2015-epg-decrypt): Remove unused var `result`.
(mml2015-epg-verify): Remove unused vars `plain` and `signature-file`.
* lisp/gnus/nnbabyl.el (nnml-current-directory): Declare var.
* lisp/gnus/nndiary.el (nndiary-files): Move declaration before first use.
* lisp/gnus/nnfolder.el (nnfolder-request-accept-article):
Remove unused var `buf`.
* lisp/gnus/nnmail.el (nnmail-parse-active): Remove unused var `err`.
* lisp/gnus/nnmairix.el (nnmairix-request-group): Remove unused var `args`.
(nnmairix-request-create-group): Remove unused var `info`.
(nnmairix-request-list): Remove unused var `folder`.
(nnmairix-request-set-mark): Remove unused var `propto`.
(nnmairix-request-set-mark): Remove unused vars `number` and `method`.
(nnmairix-close-group): Remove unused var `method`.
(nnmairix-create-search-group-from-message): Remove unused var `cq`.
(nnmairix-create-server-and-default-group): Remove unused var `create`.
(nnmairix-purge-old-groups): Remove unused var `folder`.
(nnmairix-remove-tick-mark-original-article, nnmairix-get-valid-servers):
Remove unused var `cur`.
(nnmairix-replace-group-and-numbers): Remove unused var `header`.
(nnmairix-goto-original-article): Remove unused var `rval`.
(nnmairix-widget-create-query): Remove unused var `allwidgets`.
* lisp/gnus/nnmbox.el (nnml-current-directory): Declare var.
* lisp/gnus/nnmh.el (nnmh-toplev): Move declaration before first use.
(nnmh-request-list-1): Remove unused var `rdir`.
* lisp/gnus/nnml.el (nnml-generate-nov-file): Remove unused var `file`.
* lisp/gnus/nnrss.el (nnrss-request-article): Remove unused var `post`.
(nnrss-request-article): Remove unused var `fn`.
(nnrss-check-group): Remove unused var `rdf-ns`.
* lisp/gnus/nnweb.el (nnweb-request-article): Remove unused var `active`.
(nnweb-google-parse-1): Remove unused var `Score`.
* lisp/gnus/spam-stat.el (spam-stat-error-holder): Remove var.
(spam-stat-buffer-words-with-scores): Remove unused var `word`.
(spam-stat-score-buffer): Remove unused var `spam-stat-error-holder`.
(spam-stat-split-fancy): Use `err` instead of `spam-stat-error-holder`.
* lisp/gnus/spam-wash.el (spam-wash): Remove unused var `handle`.
* lisp/gnus/spam.el (spam-copy-or-move-routine): Remove unused vars
`article` and `mark`.
(spam-register-routine): Remove unused var `article`.
(spam-log-undo-registration): Remove unused var `found`.
(spam-ifile-register-with-ifile): Remove unused var `parameters`.
(spam-check-stat): Remove unused vars `category` and `return`.
(spam-parse-list): Remove unused var `found`.
(spam-filelist-register-routine): Remove unused var `from`.

lisp/gnus/gnus-art.el

@@ -1,4 +1,4 @@
-;;; gnus-art.el --- article mode commands for Gnus
+;;; gnus-art.el --- article mode commands for Gnus  -*- lexical-binding: t; -*-
 
 ;; Copyright (C) 1996-2021 Free Software Foundation, Inc.
 
@@ -1432,7 +1432,7 @@ See Info node `(gnus)Customizing Articles' and Info node
 		 (message "\
 ** gnus-treat-display-xface is an obsolete variable;\
  use gnus-treat-display-x-face instead")
-		 (eval (car (get 'gnus-treat-display-xface 'saved-value))))
+		 (eval (car (get 'gnus-treat-display-xface 'saved-value)) t))
 		(t
 		 value)))))
 (put 'gnus-treat-display-x-face 'highlight t)
@@ -2162,6 +2162,8 @@ MAP is an alist where the elements are on the form (\"from\" \"to\")."
 	      (put-text-property
 	       (point) (1+ (point)) 'face 'underline)))))))))
 
+(defvar ansi-color-context-region)
+
 (defun article-treat-ansi-sequences ()
   "Translate ANSI SGR control sequences into overlays or extents."
   (interactive)
@@ -2893,7 +2895,7 @@ message header will be added to the bodies of the \"text/html\" parts."
 					  (t "<br>\n"))))
 		   (goto-char (point-min))
 		   (while (re-search-forward "^[\t ]+" nil t)
-		     (dotimes (i (prog1
+		     (dotimes (_ (prog1
 				     (current-column)
 				   (delete-region (match-beginning 0)
 						  (match-end 0))))
@@ -3021,6 +3023,8 @@ message header will be added to the bodies of the \"text/html\" parts."
 	       (setq showed t)))))
     showed))
 
+(defvar gnus-mime-display-attachment-buttons-in-header)
+
 (defun gnus-article-browse-html-article (&optional arg)
   "View \"text/html\" parts of the current article with a WWW browser.
 Inline images embedded in a message using the cid scheme, as they are
@@ -4712,8 +4716,6 @@ If ALL-HEADERS is non-nil, no headers are hidden."
 	    (gnus-run-hooks 'gnus-article-prepare-hook)
 	    t))))))
 
-(defvar gnus-mime-display-attachment-buttons-in-header)
-
 ;;;###autoload
 (defun gnus-article-prepare-display ()
   "Make the current buffer look like a nice article."
@@ -6149,7 +6151,7 @@ If nil, don't show those extra buttons."
   (let* ((preferred (or preferred (mm-preferred-alternative handles)))
 	 (ihandles handles)
 	 (point (point))
-	 handle (inhibit-read-only t) from begend not-pref)
+	 handle (inhibit-read-only t) begend not-pref) ;; from
     (save-window-excursion
       (save-restriction
 	(when ibegend
@@ -6170,7 +6172,8 @@ If nil, don't show those extra buttons."
 		  (not (gnus-unbuttonized-mime-type-p
 			"multipart/alternative")))
 	  (add-text-properties
-	   (setq from (point))
+	   ;; (setq from
+	   (point);; )
 	   (progn
 	     (insert (format "%d.  " id))
 	     (point))
@@ -6191,7 +6194,8 @@ If nil, don't show those extra buttons."
 	  ;; Do the handles
 	  (while (setq handle (pop handles))
 	    (add-text-properties
-	     (setq from (point))
+	     ;; (setq from
+	     (point) ;; )
 	     (progn
 	       (insert (format "(%c) %-18s"
 			       (if (equal handle preferred) ?* ? )
@@ -7986,13 +7990,13 @@ specified by `gnus-button-alist'."
       (article-goto-body)
       (setq beg (point))
       (while (setq entry (pop alist))
-	(setq regexp (eval (car entry)))
+	(setq regexp (eval (car entry) t))
 	(goto-char beg)
 	(while (re-search-forward regexp nil t)
 	  (let ((start (match-beginning (nth 1 entry)))
 		(end (match-end (nth 1 entry)))
 		(from (match-beginning 0)))
-	    (when (and (eval (nth 2 entry))
+	    (when (and (eval (nth 2 entry) t)
 		       (not (gnus-button-in-region-p
 			     start end 'gnus-callback)))
 	      ;; That optional form returned non-nil, so we add the
@@ -8083,14 +8087,14 @@ url is put as the `gnus-button-url' overlay property on the button."
 			     (match-beginning 0))
 			(point-max)))
 	  (goto-char beg)
-	  (while (re-search-forward (eval (nth 1 entry)) end t)
+	  (while (re-search-forward (eval (nth 1 entry) t) end t)
 	    ;; Each match within a header.
 	    (let* ((entry (cdr entry))
 		   (start (match-beginning (nth 1 entry)))
 		   (end (match-end (nth 1 entry)))
 		   (form (nth 2 entry)))
 	      (goto-char (match-end 0))
-	      (when (eval form)
+	      (when (eval form t)
 		(gnus-article-add-button
 		 start end (nth 3 entry)
 		 (buffer-substring (match-beginning (nth 4 entry))
@@ -8099,7 +8103,7 @@ url is put as the `gnus-button-url' overlay property on the button."
 
 ;;; External functions:
 
-(defun gnus-article-add-button (from to fun &optional data text)
+(defun gnus-article-add-button (from to fun &optional data _text)
   "Create a button between FROM and TO with callback FUN and data DATA."
   (add-text-properties
    from to
@@ -8312,7 +8316,7 @@ url is put as the `gnus-button-url' overlay property on the button."
       (setq indx  (match-string 1 indx))
       (Info-index indx)
       (when comma
-	(dotimes (i (with-temp-buffer
+	(dotimes (_ (with-temp-buffer
 		      (insert comma)
 		      ;; Note: the XEmacs version of `how-many' takes
 		      ;; no optional argument.