* 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-sum.el

@@ -3186,7 +3186,7 @@ The following commands are available:
                           ;; Copy the global value of the variable.
                           (symbol-value (car local))
                         ;; Use the value from the list.
-                        (eval (cdr local)))))
+                        (eval (cdr local) t))))
           (set (make-local-variable (car local)) global))
       ;; Simple nil-valued local variable.
       (set (make-local-variable local) nil))))
@@ -3850,7 +3850,7 @@ buffer that was in action when the last article was fetched."
     (condition-case ()
 	(put-text-property
 	 (point)
-	 (progn (eval gnus-summary-line-format-spec) (point))
+	 (progn (eval gnus-summary-line-format-spec t) (point))
 	 'gnus-number gnus-tmp-number)
       (error (gnus-message 5 "Error updating the summary line")))
     (when (gnus-visual-p 'summary-highlight 'highlight)
@@ -3971,14 +3971,14 @@ Input should look like this: \"Sun, 14 Oct 2001 13:34:39 +0200\"."
 	     (my-format "%b %d '%y"))
 	(let* ((difference (time-subtract now messy-date))
 	       (templist gnus-user-date-format-alist)
-	       (top (eval (caar templist))))
+	       (top (eval (caar templist) t)))
 	  (while (if (numberp top) (time-less-p top difference) (not top))
 	    (progn
 	      (setq templist (cdr templist))
-	      (setq top (eval (caar templist)))))
+	      (setq top (eval (caar templist) t))))
 	  (if (stringp (cdr (car templist)))
 	      (setq my-format (cdr (car templist)))))
-	(format-time-string (eval my-format) messy-date))
+	(format-time-string (eval my-format t) messy-date))
     (error "  ?   ")))
 
 (defun gnus-summary-set-local-parameters (group)
@@ -3997,8 +3997,8 @@ Input should look like this: \"Sun, 14 Oct 2001 13:34:39 +0200\"."
 	     ;; buffer-local, whereas just parameters like `gcc-self',
 	     ;; `timestamp', etc. should not be bound as variables.
 	     (if (boundp (car elem))
-		 (set (make-local-variable (car elem)) (eval (nth 1 elem)))
-	       (eval (nth 1 elem))))))))
+		 (set (make-local-variable (car elem)) (eval (nth 1 elem) t))
+	       (eval (nth 1 elem) t)))))))
 
 (defun gnus-summary-read-group (group &optional show-all no-article
 				      kill-buffer no-display backward
@@ -5557,7 +5557,7 @@ or a straight list of headers."
             (setq gnus-tmp-thread thread)
 	    (put-text-property
 	     (point)
-	     (progn (eval gnus-summary-line-format-spec) (point))
+	     (progn (eval gnus-summary-line-format-spec t) (point))
 	     'gnus-number number)
 	    (when gnus-visual-p
 	      (forward-line -1)
@@ -6265,7 +6265,7 @@ If WHERE is `summary', the summary mode line format will be used."
 		  ""))
 	       bufname-length max-len
 	       gnus-tmp-header)	;; passed as argument to any user-format-funcs
-	  (setq mode-string (eval mformat))
+	  (setq mode-string (eval mformat t))
 	  (setq bufname-length (if (string-match "%b" mode-string)
 				   (- (length
 				       (buffer-name
@@ -7863,7 +7863,7 @@ If BACKWARD, the previous article is selected instead of the next."
 	  (switch-to-buffer gnus-group-buffer)
 	  (when group
 	    (gnus-group-jump-to-group group))
-	  (eval (cadr (assq key keystrokes)))
+	  (eval (cadr (assq key keystrokes)) t)
 	  (setq group (gnus-group-group-name))
 	  (switch-to-buffer obuf))
 	(setq ended nil))
@@ -10617,6 +10617,8 @@ confirmation before the articles are deleted."
     (gnus-set-mode-line 'summary)
     not-deleted))
 
+(defvar message-options-set-recipient)
+
 (defun gnus-summary-edit-article (&optional arg)
   "Edit the current article.
 This will have permanent effect only in mail groups.
@@ -12366,7 +12368,7 @@ save those articles instead."
 		    ;; Form.
 		    (save-restriction
 		      (widen)
-		      (setq result (eval match)))))
+		      (setq result (eval match t)))))
 	      (setq split-name (cdr method))
 	      (cond ((stringp result)
 		     (push (expand-file-name
@@ -12956,7 +12958,7 @@ treated as multipart/mixed."
 		    (nomove "" nil nil ,keystroke)))
       (let ((func (gnus-summary-make-marking-command-1
 		   mark (car lway) lway name)))
-	(setq func (eval func))
+	(setq func (eval func t))
 	(define-key map (nth 4 lway) func)))))
 
 (defun gnus-summary-make-marking-command-1 (mark way lway name)