* lisp/gnus/gnus-agent.el (gnus-category-mode): Use define-derived-mode.

(gnus-agent-mode): Use derived-mode-p.
(gnus-agent-rename-group, gnus-agent-delete-group): Don't bind
gnus-command-method and *-command-method to nil, but bind
gnus-command-method to *-command-method instead!
(gnus-agent-fetch-articles): Remove unused var `id'.
(gnus-agent-fetch-headers): Remove unused arg `force'.
(gnus-agent-braid-nov): Remove unused arg `group'.  Adjust callers.
(gnus-agent-save-alist, gnus-agent-save-local): Remove unused `item'.
(gnus-agent-short-article, gnus-agent-long-article)
(gnus-agent-low-score, gnus-agent-high-score): Move declaration before
first use.
(gnus-agent-fetch-group-1): Remove unused vars `arts', `category',
`score-param'.
(gnus-tmp-name, gnus-tmp-groups): Defvar them.
(gnus-get-predicate): Push in front of the cache, rather than end.
(gnus-agent-expire-current-dirs, gnus-agent-expire-stats): Defvar them.
(gnus-agent-expire-group-1): Use push.  Don't abuse dyn-binding.
(gnus-agent-expire-unagentized-dirs): Don't rebind
gnus-agent-expire-current-dirs since the defvar silences the warning.
(gnus-agent-retrieve-headers): Remove unused var `cached-articles'.
(gnus-agent-regenerate-group): Remove unused vars `point' and `dl'.
(gnus-agent-regenerate): Simplify interactive spec and doc.

* lisp/gnus/gnus-eform.el (gnus-edit-form-mode): Use define-derived-mode.

* lisp/gnus/gnus-salt.el (gnus-tree-mode): Use define-derived-mode.
Use save-current-buffer.
(gnus-tree-mode-map): Initialize in the declaration.
(gnus-pick-mouse-pick-region): Remove unused var `fun'.
(scroll-in-place): Defvar it.
(gnus-tmp-*): Defvar them.
(gnus-get-tree-buffer): Use derived-mode-p.
(gnus--let-eval): New macro.
(gnus-tree-highlight-node): Use it to avoid dynamic binding of
non-prefixed variables.
(gnus-tree-open, gnus-tree-close): Remove unused arg `group'.

* lisp/gnus/gnus-sum.el (gnus-summary-highlight): Remove `below' from the list of
vars since it doesn't seem to be available.
(gnus-set-global-variables, gnus-summary-read-group-1)
(gnus-select-newsgroup, gnus-handle-ephemeral-exit)
(gnus-summary-display-article, gnus-summary-select-article)
(gnus-summary-next-article, gnus-offer-save-summaries)
(gnus-summary-generic-mark): Use derived-mode-p.
(gnus-summary-read-group-1, gnus-summary-exit)
(gnus-summary-exit-no-update, gnus-kill-or-deaden-summary):
Adjust calls to gnus-tree-close and gnus-tree-open.

5 files changed, 202 insertions, 155 deletions

diff --git a/lisp/gnus/ChangeLog b/lisp/gnus/ChangeLog
index f9c0c7b287e..d673a18cb1d 100644
--- a/lisp/gnus/ChangeLog
+++ b/lisp/gnus/ChangeLog
@@ -1,3 +1,54 @@
+2013-09-17  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * gnus-salt.el (gnus-tree-mode): Use define-derived-mode.
+        Use save-current-buffer.
+        (gnus-tree-mode-map): Initialize in the declaration.
+        (gnus-pick-mouse-pick-region): Remove unused var `fun'.
+        (scroll-in-place): Defvar it.
+        (gnus-tmp-*): Defvar them.
+        (gnus-get-tree-buffer): Use derived-mode-p.
+        (gnus--let-eval): New macro.
+        (gnus-tree-highlight-node): Use it to avoid dynamic binding of
+        non-prefixed variables.
+        (gnus-tree-open, gnus-tree-close): Remove unused arg `group'.
+
+        * gnus-sum.el (gnus-summary-highlight): Remove `below' from the list of
+        vars since it doesn't seem to be available.
+        (gnus-set-global-variables, gnus-summary-read-group-1)
+        (gnus-select-newsgroup, gnus-handle-ephemeral-exit)
+        (gnus-summary-display-article, gnus-summary-select-article)
+        (gnus-summary-next-article, gnus-offer-save-summaries)
+        (gnus-summary-generic-mark): Use derived-mode-p.
+        (gnus-summary-read-group-1, gnus-summary-exit)
+        (gnus-summary-exit-no-update, gnus-kill-or-deaden-summary):
+        Adjust calls to gnus-tree-close and gnus-tree-open.
+
+        * gnus-eform.el (gnus-edit-form-mode): Use define-derived-mode.
+
+        * gnus-agent.el (gnus-category-mode): Use define-derived-mode.
+        (gnus-agent-mode): Use derived-mode-p.
+        (gnus-agent-rename-group, gnus-agent-delete-group): Don't bind
+        gnus-command-method and *-command-method to nil, but bind
+        gnus-command-method to *-command-method instead!
+        (gnus-agent-fetch-articles): Remove unused var `id'.
+        (gnus-agent-fetch-headers): Remove unused arg `force'.
+        (gnus-agent-braid-nov): Remove unused arg `group'.  Adjust callers.
+        (gnus-agent-save-alist, gnus-agent-save-local): Remove unused `item'.
+        (gnus-agent-short-article, gnus-agent-long-article)
+        (gnus-agent-low-score, gnus-agent-high-score): Move declaration before
+        first use.
+        (gnus-agent-fetch-group-1): Remove unused vars `arts', `category',
+        `score-param'.
+        (gnus-tmp-name, gnus-tmp-groups): Defvar them.
+        (gnus-get-predicate): Push in front of the cache, rather than end.
+        (gnus-agent-expire-current-dirs, gnus-agent-expire-stats): Defvar them.
+        (gnus-agent-expire-group-1): Use push.  Don't abuse dyn-binding.
+        (gnus-agent-expire-unagentized-dirs): Don't rebind
+        gnus-agent-expire-current-dirs since the defvar silences the warning.
+        (gnus-agent-retrieve-headers): Remove unused var `cached-articles'.
+        (gnus-agent-regenerate-group): Remove unused vars `point' and `dl'.
+        (gnus-agent-regenerate): Simplify interactive spec and doc.
+
 2013-09-17  Katsumi Yamaoka  <yamaoka@jpl.org>
 
         * gnus-int.el (gnus-open-server): Silence compiler.
diff --git a/lisp/gnus/gnus-agent.el b/lisp/gnus/gnus-agent.el
index 1d0f346e10f..10ee230a814 100644
--- a/lisp/gnus/gnus-agent.el
+++ b/lisp/gnus/gnus-agent.el
@@ -492,7 +492,7 @@ manipulated as follows:
       (push (cons mode (symbol-value (intern (format "gnus-agent-%s-mode-map"
                                                      buffer))))
             minor-mode-map-alist))
-    (when (eq major-mode 'gnus-group-mode)
+    (when (derived-mode-p 'gnus-group-mode)
       (let ((init-plugged gnus-plugged)
             (gnus-agent-go-online nil))
         ;; g-a-t-p does nothing when gnus-plugged isn't changed.
@@ -881,11 +881,11 @@ Depends upon the caller to determine whether group renaming is
 supported."
   (let* ((old-command-method (gnus-find-method-for-group old-group))
          (old-path           (directory-file-name
-                              (let (gnus-command-method old-command-method)
+                              (let ((gnus-command-method old-command-method))
                                 (gnus-agent-group-pathname old-group))))
          (new-command-method (gnus-find-method-for-group new-group))
          (new-path           (directory-file-name
-                              (let (gnus-command-method new-command-method)
+                              (let ((gnus-command-method new-command-method))
                                 (gnus-agent-group-pathname new-group))))
          (file-name-coding-system nnmail-pathname-coding-system))
     (gnus-rename-file old-path new-path t)
@@ -914,19 +914,18 @@ Depends upon the caller to determine whether group deletion is
 supported."
   (let* ((command-method (gnus-find-method-for-group group))
          (path           (directory-file-name
-                          (let (gnus-command-method command-method)
+                          (let ((gnus-command-method command-method))
                             (gnus-agent-group-pathname group))))
          (file-name-coding-system nnmail-pathname-coding-system))
     (gnus-delete-directory path)
 
     (let* ((real-group (gnus-group-real-name group)))
       (gnus-agent-save-group-info command-method real-group nil)
-
-      (let ((local (gnus-agent-get-local group
-                                         real-group command-method)))
-        (gnus-agent-set-local group
-                              nil nil
-                              real-group command-method)))))
+      ;; FIXME: Does gnus-agent-get-local have any useful side-effect?
+      (gnus-agent-get-local group real-group command-method)
+      (gnus-agent-set-local group
+                            nil nil
+                            real-group command-method))))
 
 ;;;
 ;;; Server mode commands
@@ -1549,7 +1548,7 @@ downloaded into the agent."
                (dir (gnus-agent-group-pathname group))
                (date (time-to-days (current-time)))
                (case-fold-search t)
-               pos crosses id
+               pos crosses
                (file-name-coding-system nnmail-pathname-coding-system))
 
           (setcar selected-sets (nreverse (car selected-sets)))
@@ -1603,11 +1602,6 @@ downloaded into the agent."
                             (goto-char (match-end 0)))
                           (gnus-agent-crosspost crosses (caar pos) date)))
                       (goto-char (point-min))
-                      (if (not (re-search-forward
-                                "^Message-ID: *<\\([^>\n]+\\)>" nil t))
-                          (setq id "No-Message-ID-in-article")
-                        (setq id (buffer-substring
-                                  (match-beginning 1) (match-end 1))))
                       (let ((coding-system-for-write
                              gnus-agent-file-coding-system))
                         (write-region (point-min) (point-max)
@@ -1832,7 +1826,7 @@ variables.  Returns the first non-nil value found."
                  . gnus-agent-enable-expiration)
                 (agent-predicate . gnus-agent-predicate)))))))
 
-(defun gnus-agent-fetch-headers (group &optional force)
+(defun gnus-agent-fetch-headers (group)
   "Fetch interesting headers into the agent.  The group's overview
 file will be updated to include the headers while a list of available
 article numbers will be returned."
@@ -1931,7 +1925,7 @@ article numbers will be returned."
               ;; NOTE: Call g-a-brand-nov even when the file does not
               ;; exist.  As a minimum, it will validate the article
               ;; numbers already in the buffer.
-              (gnus-agent-braid-nov group articles file)
+              (gnus-agent-braid-nov articles file)
               (let ((coding-system-for-write
                      gnus-agent-file-coding-system))
                 (gnus-agent-check-overview-buffer)
@@ -1980,7 +1974,7 @@ article numbers will be returned."
       (set-buffer nntp-server-buffer)
       (insert-buffer-substring gnus-agent-overview-buffer b e))))
 
-(defun gnus-agent-braid-nov (group articles file)
+(defun gnus-agent-braid-nov (articles file)
   "Merge agent overview data with given file.
 Takes unvalidated headers for ARTICLES from
 `gnus-agent-overview-buffer' and validated headers from the given
@@ -2154,7 +2148,7 @@ doesn't exist, to valid the overview buffer."
   (let* ((file-name-coding-system nnmail-pathname-coding-system)
          (prev (cons nil gnus-agent-article-alist))
          (all prev)
-         print-level print-length item article)
+         print-level print-length article)
     (while (setq article (pop articles))
       (while (and (cdr prev)
                   (< (caadr prev) article))
@@ -2288,7 +2282,7 @@ modified) original contents, they are first saved to their own file."
               (file-name-coding-system nnmail-pathname-coding-system))
           (with-temp-file dest
             (let ((gnus-command-method (symbol-value (intern "+method" my-obarray)))
-                  print-level print-length item article
+                  print-level print-length
                   (standard-output (current-buffer)))
               (mapatoms (lambda (symbol)
                           (cond ((not (boundp symbol))
@@ -2411,6 +2405,18 @@ modified) original contents, they are first saved to their own file."
       (gnus-run-hooks 'gnus-agent-fetched-hook)
       (gnus-message 6 "Finished fetching articles into the Gnus agent"))))
 
+(defvar gnus-agent-short-article 500
+  "Articles that have fewer lines than this are short.")
+
+(defvar gnus-agent-long-article 1000
+  "Articles that have more lines than this are long.")
+
+(defvar gnus-agent-low-score 0
+  "Articles that have a score lower than this have a low score.")
+
+(defvar gnus-agent-high-score 0
+  "Articles that have a score higher than this have a high score.")
+
 (defun gnus-agent-fetch-group-1 (group method)
   "Fetch GROUP."
   (let ((gnus-command-method method)
@@ -2427,8 +2433,8 @@ modified) original contents, they are first saved to their own file."
 
         gnus-headers
         gnus-score
-        articles arts
-        category predicate info marks score-param
+        articles
+        predicate info marks
         )
     (unless (gnus-check-group group)
       (error "Can't open server for %s" group))
@@ -2471,9 +2477,6 @@ modified) original contents, they are first saved to their own file."
           ;; timeout reason.  If so, recreate it.
           (gnus-agent-create-buffer)
 
-          ;; Figure out how to select articles in this group
-          (setq category (gnus-group-category group))
-
           (setq predicate
                 (gnus-get-predicate
                  (gnus-agent-find-parameter group 'agent-predicate)))
@@ -2624,23 +2627,14 @@ General format specifiers can also be used.  See Info node
 (defvar gnus-agent-predicate 'false
   "The selection predicate used when no other source is available.")
 
-(defvar gnus-agent-short-article 500
-  "Articles that have fewer lines than this are short.")
-
-(defvar gnus-agent-long-article 1000
-  "Articles that have more lines than this are long.")
-
-(defvar gnus-agent-low-score 0
-  "Articles that have a score lower than this have a low score.")
-
-(defvar gnus-agent-high-score 0
-  "Articles that have a score higher than this have a high score.")
-
 
 ;;; Internal variables.
 
 (defvar gnus-category-buffer "*Agent Category*")
 
+(defvar gnus-tmp-name)
+(defvar gnus-tmp-groups)
+
 (defvar gnus-category-line-format-alist
   `((?c gnus-tmp-name ?s)
     (?g gnus-tmp-groups ?d)))
@@ -2692,7 +2686,7 @@ General format specifiers can also be used.  See Info node
 
     (gnus-run-hooks 'gnus-category-menu-hook)))
 
-(defun gnus-category-mode ()
+(define-derived-mode gnus-category-mode fundamental-mode "Category"
   "Major mode for listing and editing agent categories.
 
 All normal editing commands are switched off.
@@ -2703,20 +2697,14 @@ For more in-depth information on this mode, read the manual
 The following commands are available:
 
 \\{gnus-category-mode-map}"
-  (interactive)
   (when (gnus-visual-p 'category-menu 'menu)
     (gnus-category-make-menu-bar))
-  (kill-all-local-variables)
   (gnus-simplify-mode-line)
-  (setq major-mode 'gnus-category-mode)
-  (setq mode-name "Category")
   (gnus-set-default-directory)
   (setq mode-line-process nil)
-  (use-local-map gnus-category-mode-map)
   (buffer-disable-undo)
   (setq truncate-lines t)
-  (setq buffer-read-only t)
-  (gnus-run-mode-hooks 'gnus-category-mode-hook))
+  (setq buffer-read-only t))
 
 (defalias 'gnus-category-position-point 'gnus-goto-colon)
 
@@ -2992,9 +2980,7 @@ The following commands are available:
   "Return the function implementing PREDICATE."
   (or (cdr (assoc predicate gnus-category-predicate-cache))
       (let ((func (gnus-category-make-function predicate)))
-        (setq gnus-category-predicate-cache
-              (nconc gnus-category-predicate-cache
-                     (list (cons predicate func))))
+        (push (cons predicate func) gnus-category-predicate-cache)
         func)))
 
 (defun gnus-predicate-implies-unread (predicate)
@@ -3066,6 +3052,9 @@ articles."
   (or (gnus-gethash group gnus-category-group-cache)
       (assq 'default gnus-category-alist)))
 
+(defvar gnus-agent-expire-current-dirs)
+(defvar gnus-agent-expire-stats)
+
 (defun gnus-agent-expire-group (group &optional articles force)
   "Expire all old articles in GROUP.
 If you want to force expiring of certain articles, this function can
@@ -3080,7 +3069,7 @@ FORCE is equivalent to setting the expiration predicates to true."
 
   (if (not group)
       (gnus-agent-expire articles group force)
-    (let ( ;; Bind gnus-agent-expire-stats to enable tracking of
+    (let (;; Bind gnus-agent-expire-stats to enable tracking of
           ;; expiration statistics of this single group
           (gnus-agent-expire-stats (list 0 0 0.0)))
       (if (or (not (eq articles t))
@@ -3117,9 +3106,7 @@ FORCE is equivalent to setting the expiration predicates to true."
     (gnus-agent-with-refreshed-group
      group
      (when (boundp 'gnus-agent-expire-current-dirs)
-       (set 'gnus-agent-expire-current-dirs
-            (cons dir
-                  (symbol-value 'gnus-agent-expire-current-dirs))))
+       (push dir gnus-agent-expire-current-dirs))
 
      (if (and (not force)
               (eq 'DISABLE (gnus-agent-find-parameter group
@@ -3263,24 +3250,24 @@ line." (point) nov-file)))
          ;; only problem is that much of it is spread across multiple
          ;; entries.  Sort then MERGE!!
          (gnus-message 7 "gnus-agent-expire: Sorting entries... ")
-         ;; If two entries have the same article-number then sort by
-         ;; ascending keep_flag.
-         (let ((special 0)
-               (marked 1)
-               (unread 2))
-           (setq dlist
-                 (sort dlist
-                       (lambda (a b)
-                         (cond ((< (nth 0 a) (nth 0 b))
-                                t)
-                               ((> (nth 0 a) (nth 0 b))
-                                nil)
-                               (t
-                                (let ((a (or (symbol-value (nth 2 a))
-                                             3))
-                                      (b (or (symbol-value (nth 2 b))
-                                             3)))
-                                  (<= a b))))))))
+         (setq dlist
+               (sort dlist
+                     (lambda (a b)
+                       (cond ((< (nth 0 a) (nth 0 b))
+                              t)
+                             ((> (nth 0 a) (nth 0 b))
+                              nil)
+                             (t
+                              ;; If two entries have the same article-number
+                              ;; then sort by ascending keep_flag.
+                              (let* ((kf-score '((special . 0)
+                                                 (marked . 1)
+                                                 (unread . 2)))
+                                     (a (or (cdr (assq (nth 2 a) kf-score))
+                                            3))
+                                     (b (or (cdr (assq (nth 2 b) kf-score))
+                                            3)))
+                                (<= a b)))))))
          (gnus-message 7 "gnus-agent-expire: Sorting entries... Done")
          (gnus-message 7 "gnus-agent-expire: Merging entries... ")
          (let ((dlist dlist))
@@ -3474,7 +3461,7 @@ expiration tests failed." decoded article-number)
                (gnus-summary-update-info))))
 
          (when (boundp 'gnus-agent-expire-stats)
-           (let ((stats (symbol-value 'gnus-agent-expire-stats)))
+           (let ((stats gnus-agent-expire-stats))
              (incf (nth 2 stats) bytes-freed)
              (incf (nth 1 stats) files-deleted)
              (incf (nth 0 stats) nov-entries-deleted)))
@@ -3534,7 +3521,7 @@ articles in every agentized group? "))
 (defun gnus-agent-expire-done-message ()
   (if (and (> gnus-verbose 4)
            (boundp 'gnus-agent-expire-stats))
-      (let* ((stats (symbol-value 'gnus-agent-expire-stats))
+      (let* ((stats gnus-agent-expire-stats)
              (size (nth 2 stats))
             (units '(B KB MB GB)))
         (while (and (> size 1024.0)
@@ -3553,16 +3540,10 @@ articles in every agentized group? "))
   (when (and gnus-agent-expire-unagentized-dirs
              (boundp 'gnus-agent-expire-current-dirs))
     (let* ((keep (gnus-make-hashtable))
-           ;; Formally bind gnus-agent-expire-current-dirs so that the
-           ;; compiler will not complain about free references.
-           (gnus-agent-expire-current-dirs
-            (symbol-value 'gnus-agent-expire-current-dirs))
-           dir
            (file-name-coding-system nnmail-pathname-coding-system))
 
       (gnus-sethash gnus-agent-directory t keep)
-      (while gnus-agent-expire-current-dirs
-        (setq dir (pop gnus-agent-expire-current-dirs))
+      (dolist (dir gnus-agent-expire-current-dirs)
         (when (and (stringp dir)
                    (file-directory-p dir))
           (while (not (gnus-gethash dir keep))
@@ -3715,7 +3696,7 @@ has been fetched."
     (let ((gnus-decode-encoded-word-function 'identity)
           (gnus-decode-encoded-address-function 'identity)
           (file (gnus-agent-article-name ".overview" group))
-          cached-articles uncached-articles
+          uncached-articles
           (file-name-coding-system nnmail-pathname-coding-system))
       (gnus-make-directory (nnheader-translate-file-chars
                             (file-name-directory file) t))
@@ -3812,7 +3793,7 @@ has been fetched."
             ;; Merge the temp buffer with the known headers (found on
             ;; disk in FILE) into the nntp-server-buffer
             (when uncached-articles
-              (gnus-agent-braid-nov group uncached-articles file))
+              (gnus-agent-braid-nov uncached-articles file))
 
             ;; Save the new set of known headers to FILE
             (set-buffer nntp-server-buffer)
@@ -3907,7 +3888,6 @@ If REREAD is not nil, downloaded articles are marked as unread."
                                     (gnus-find-method-for-group group)))
            (file (gnus-agent-article-name ".overview" group))
            (dir (file-name-directory file))
-           point
            (file-name-coding-system nnmail-pathname-coding-system)
            (downloaded (if (file-exists-p dir)
                            (sort (delq nil (mapcar (lambda (name)
@@ -3916,7 +3896,7 @@ If REREAD is not nil, downloaded articles are marked as unread."
                                                    (directory-files dir nil "^[0-9]+$" t)))
                                  '>)
                          (progn (gnus-make-directory dir) nil)))
-           dl nov-arts
+           nov-arts
            alist header
            regenerated)
 
@@ -4099,16 +4079,16 @@ If REREAD is not nil, downloaded articles are marked as unread."
       regenerated)))
 
 ;;;###autoload
-(defun gnus-agent-regenerate (&optional clean reread)
+(defun gnus-agent-regenerate (&optional _clean reread)
   "Regenerate all agent covered files.
-If CLEAN, obsolete (ignore)."
-  (interactive "P")
+CLEAN is obsolete and ignored."
+  (interactive)
   (let (regenerated)
     (gnus-message 4 "Regenerating Gnus agent files...")
     (dolist (gnus-command-method (gnus-agent-covered-methods))
-        (dolist (group (gnus-groups-from-server gnus-command-method))
-          (setq regenerated (or (gnus-agent-regenerate-group group reread)
-                                regenerated))))
+      (dolist (group (gnus-groups-from-server gnus-command-method))
+        (setq regenerated (or (gnus-agent-regenerate-group group reread)
+                              regenerated))))
     (gnus-message 4 "Regenerating Gnus agent files...done")
 
     regenerated))
diff --git a/lisp/gnus/gnus-eform.el b/lisp/gnus/gnus-eform.el
index 6790803305a..00e27876088 100644
--- a/lisp/gnus/gnus-eform.el
+++ b/lisp/gnus/gnus-eform.el
@@ -67,21 +67,15 @@
        ["Exit" gnus-edit-form-exit t]))
     (gnus-run-hooks 'gnus-edit-form-menu-hook)))
 
-(defun gnus-edit-form-mode ()
+(define-derived-mode gnus-edit-form-mode fundamental-mode "Edit Form"
   "Major mode for editing forms.
 It is a slightly enhanced emacs-lisp-mode.
 
 \\{gnus-edit-form-mode-map}"
-  (interactive)
   (when (gnus-visual-p 'group-menu 'menu)
     (gnus-edit-form-make-menu-bar))
-  (kill-all-local-variables)
-  (setq major-mode 'gnus-edit-form-mode)
-  (setq mode-name "Edit Form")
-  (use-local-map gnus-edit-form-mode-map)
   (make-local-variable 'gnus-edit-form-done-function)
-  (make-local-variable 'gnus-prev-winconf)
-  (gnus-run-mode-hooks 'gnus-edit-form-mode-hook))
+  (make-local-variable 'gnus-prev-winconf))
 
 (defun gnus-edit-form (form documentation exit-func &optional layout)
   "Edit FORM in a new buffer.
diff --git a/lisp/gnus/gnus-salt.el b/lisp/gnus/gnus-salt.el
index 6b8e105e6b8..77fe0d3bb14 100644
--- a/lisp/gnus/gnus-salt.el
+++ b/lisp/gnus/gnus-salt.el
@@ -292,22 +292,25 @@ This must be bound to a button-down mouse event."
                   (mouse-scroll-subr start-window
                                      (1+ (- mouse-row bottom)))))))))))
       (when (consp event)
-        (let ((fun (key-binding (vector (car event)))))
+        (let (;; (fun (key-binding (vector (car event))))
+              )
           ;; Run the binding of the terminating up-event, if possible.
-       ;; In the case of a multiple click, it gives the wrong results,
+          ;; In the case of a multiple click, it gives the wrong results,
           ;; because it would fail to set up a region.
           (when nil
-      ;; (and (= (mod mouse-selection-click-count 3) 0) (fboundp fun))
-       ;; In this case, we can just let the up-event execute normally.
+            ;; (and (= (mod mouse-selection-click-count 3) 0) (fboundp fun))
+            ;; In this case, we can just let the up-event execute normally.
             (let ((end (event-end event)))
               ;; Set the position in the event before we replay it,
               ;; because otherwise it may have a position in the wrong
               ;; buffer.
               (setcar (cdr end) end-of-range)
               ;; Delete the overlay before calling the function,
-             ;; because delete-overlay increases buffer-modified-tick.
+              ;; because delete-overlay increases buffer-modified-tick.
               (push event unread-command-events))))))))
 
+(defvar scroll-in-place)
+
 (defun gnus-pick-next-page ()
   "Go to the next page.  If at the end of the buffer, start reading articles."
   (interactive)
@@ -356,7 +359,7 @@ This must be bound to a button-down mouse event."
     (when (gnus-visual-p 'binary-menu 'menu)
       (gnus-binary-make-menu-bar)))))
 
-(defun gnus-binary-display-article (article &optional all-header)
+(defun gnus-binary-display-article (article &optional _all-header)
   "Run ARTICLE through the binary decode functions."
   (when (gnus-summary-goto-subject article)
     (let ((gnus-view-pseudos (or gnus-view-pseudos 'automatic)))
@@ -423,6 +426,13 @@ Two predefined functions are available:
 
 ;;; Internal variables.
 
+(defvar gnus-tmp-name)
+(defvar gnus-tmp-from)
+(defvar gnus-tmp-number)
+(defvar gnus-tmp-open-bracket)
+(defvar gnus-tmp-close-bracket)
+(defvar gnus-tmp-subject)
+
 (defvar gnus-tree-line-format-alist
   `((?n gnus-tmp-name ?s)
     (?f gnus-tmp-from ?s)
@@ -442,23 +452,23 @@ Two predefined functions are available:
 (defvar gnus-tree-displayed-thread nil)
 (defvar gnus-tree-inhibit nil)
 
-(defvar gnus-tree-mode-map nil)
-(put 'gnus-tree-mode 'mode-class 'special)
+(defvar gnus-tree-mode-map
+  (let ((map (make-keymap)))
+    (suppress-keymap map)
+    (gnus-define-keys
+        map
+      "\r" gnus-tree-select-article
+      gnus-mouse-2 gnus-tree-pick-article
+      "\C-?" gnus-tree-read-summary-keys
+      "h" gnus-tree-show-summary
 
-(unless gnus-tree-mode-map
-  (setq gnus-tree-mode-map (make-keymap))
-  (suppress-keymap gnus-tree-mode-map)
-  (gnus-define-keys
-      gnus-tree-mode-map
-    "\r" gnus-tree-select-article
-    gnus-mouse-2 gnus-tree-pick-article
-    "\C-?" gnus-tree-read-summary-keys
-    "h" gnus-tree-show-summary
+      "\C-c\C-i" gnus-info-find-node)
 
-    "\C-c\C-i" gnus-info-find-node)
+    (substitute-key-definition
+     'undefined 'gnus-tree-read-summary-keys map)
+    map))
 
-  (substitute-key-definition
-   'undefined 'gnus-tree-read-summary-keys gnus-tree-mode-map))
+(put 'gnus-tree-mode 'mode-class 'special)
 
 (defun gnus-tree-make-menu-bar ()
   (unless (boundp 'gnus-tree-menu)
@@ -467,26 +477,20 @@ Two predefined functions are available:
       '("Tree"
         ["Select article" gnus-tree-select-article t]))))
 
-(defun gnus-tree-mode ()
+(define-derived-mode gnus-tree-mode fundamental-mode "Tree"
   "Major mode for displaying thread trees."
-  (interactive)
   (gnus-set-format 'tree-mode)
   (gnus-set-format 'tree t)
   (when (gnus-visual-p 'tree-menu 'menu)
     (gnus-tree-make-menu-bar))
-  (kill-all-local-variables)
   (gnus-simplify-mode-line)
-  (setq mode-name "Tree")
-  (setq major-mode 'gnus-tree-mode)
-  (use-local-map gnus-tree-mode-map)
   (buffer-disable-undo)
   (setq buffer-read-only t)
   (setq truncate-lines t)
-  (save-excursion
+  (save-current-buffer
     (gnus-set-work-buffer)
     (gnus-tree-node-insert (make-mail-header "") nil)
-    (setq gnus-tree-node-length (1- (point))))
-  (gnus-run-mode-hooks 'gnus-tree-mode-hook))
+    (setq gnus-tree-node-length (1- (point)))))
 
 (defun gnus-tree-read-summary-keys (&optional arg)
   "Read a summary buffer key sequence and execute it."
@@ -562,7 +566,7 @@ Two predefined functions are available:
 (defun gnus-get-tree-buffer ()
   "Return the tree buffer properly initialized."
   (with-current-buffer (gnus-get-buffer-create gnus-tree-buffer)
-    (unless (eq major-mode 'gnus-tree-mode)
+    (unless (derived-mode-p 'gnus-tree-mode)
       (gnus-tree-mode))
     (current-buffer)))
 
@@ -571,7 +575,7 @@ Two predefined functions are available:
              (not (one-window-p)))
     (let ((windows 0)
           tot-win-height)
-      (walk-windows (lambda (window) (incf windows)))
+      (walk-windows (lambda (_window) (incf windows)))
       (setq tot-win-height
             (- (frame-height)
                (* window-min-height (1- windows))
@@ -642,23 +646,41 @@ Two predefined functions are available:
     (when (or t (gnus-visual-p 'tree-highlight 'highlight))
       (gnus-tree-highlight-node gnus-tmp-number beg end))))
 
+(defmacro gnus--let-eval (bindings evalsym &rest body)
+  "Build an environment in which to evaluate expressions.
+BINDINGS is a `let'-style list of bindings to use for the environment.
+EVALSYM is then bound in BODY to a function that takes a sexp and evaluates
+it in the environment specified by BINDINGS."
+  (declare (indent 2) (debug ((&rest (sym form)) sym body)))
+  (if (ignore-errors (let ((x 3)) (eq (eval '(- x 1) '((x . 4))) x)))
+      ;; Use lexical vars if possible.
+      `(let* ((env (list ,@(mapcar (lambda (binding)
+                                     `(cons ',(car binding) ,(cadr binding)))
+                                   bindings)))
+             (,evalsym (lambda (exp) (eval exp env))))
+         ,@body)
+    `(let (,@bindings (,evalsym #'eval)) ,@body)))
+
 (defun gnus-tree-highlight-node (article beg end)
   "Highlight current line according to `gnus-summary-highlight'."
   (let ((list gnus-summary-highlight)
         face)
     (with-current-buffer gnus-summary-buffer
-      (let* ((score (or (cdr (assq article gnus-newsgroup-scored))
+      (let ((uncached (memq article gnus-newsgroup-undownloaded)))
+        (gnus--let-eval
+            ((score (or (cdr (assq article gnus-newsgroup-scored))
                         gnus-summary-default-score 0))
              (default gnus-summary-default-score)
              (default-high gnus-summary-default-high-score)
              (default-low gnus-summary-default-low-score)
-             (uncached (memq article gnus-newsgroup-undownloaded))
+             (uncached uncached)
              (downloaded (not uncached))
              (mark (or (gnus-summary-article-mark article) gnus-unread-mark)))
-        ;; Eval the cars of the lists until we find a match.
-        (while (and list
-                    (not (eval (caar list))))
-          (setq list (cdr list)))))
+            evalfun
+          ;; Eval the cars of the lists until we find a match.
+          (while (and list
+                      (not (funcall evalfun (caar list))))
+            (setq list (cdr list))))))
     (unless (eq (setq face (cdar list)) (gnus-get-text-property-excluding-characters-with-faces beg 'face))
       (gnus-put-text-property-excluding-characters-with-faces
        beg end 'face
@@ -814,10 +836,10 @@ Two predefined functions are available:
           (gnus-generate-tree top)
           (setq gnus-tree-displayed-thread top))))))
 
-(defun gnus-tree-open (group)
+(defun gnus-tree-open ()
   (gnus-get-tree-buffer))
 
-(defun gnus-tree-close (group)
+(defun gnus-tree-close ()
   (gnus-kill-buffer gnus-tree-buffer))
 
 (defun gnus-tree-perhaps-minimize ()
diff --git a/lisp/gnus/gnus-sum.el b/lisp/gnus/gnus-sum.el
index 94f4e703180..61cf7ec5b61 100644
--- a/lisp/gnus/gnus-sum.el
+++ b/lisp/gnus/gnus-sum.el
@@ -1140,7 +1140,6 @@ score:        The article's score.
 default:      The default article score.
 default-high: The default score for high scored articles.
 default-low:  The default score for low scored articles.
-below:        The score below which articles are automatically marked as read.
 mark:         The article's mark.
 uncached:     Non-nil if the article is uncached."
   :group 'gnus-summary-visual
@@ -3104,6 +3103,7 @@ buffer; read the info pages for more information (`\\[gnus-info-find-node]').
 The following commands are available:
 
 \\{gnus-summary-mode-map}"
+  ;; FIXME: Use define-derived-mode.
   (interactive)
   (kill-all-local-variables)
   (let ((gnus-summary-local-variables gnus-newsgroup-variables))
@@ -3542,7 +3542,7 @@ If the setup was successful, non-nil is returned."
   "Set the global equivalents of the buffer-local variables.
 They are set to the latest values they had.  These reflect the summary
 buffer that was in action when the last article was fetched."
-  (when (eq major-mode 'gnus-summary-mode)
+  (when (derived-mode-p 'gnus-summary-mode)
     (setq gnus-summary-buffer (current-buffer))
     (let ((name gnus-newsgroup-name)
           (marked gnus-newsgroup-marked)
@@ -3990,7 +3990,7 @@ If SELECT-ARTICLES, only select those articles from GROUP."
       t)
      ;; We couldn't select this group.
      ((null did-select)
-      (when (and (eq major-mode 'gnus-summary-mode)
+      (when (and (derived-mode-p 'gnus-summary-mode)
                  (not (equal (current-buffer) kill-buffer)))
         (kill-buffer (current-buffer))
         (if (not quit-config)
@@ -4009,7 +4009,7 @@ If SELECT-ARTICLES, only select those articles from GROUP."
      ;; The user did a `C-g' while prompting for number of articles,
      ;; so we exit this group.
      ((eq did-select 'quit)
-      (and (eq major-mode 'gnus-summary-mode)
+      (and (derived-mode-p 'gnus-summary-mode)
            (not (equal (current-buffer) kill-buffer))
            (kill-buffer (current-buffer)))
       (when kill-buffer
@@ -4052,7 +4052,7 @@ If SELECT-ARTICLES, only select those articles from GROUP."
       (unless no-display
         (gnus-summary-prepare))
       (when gnus-use-trees
-        (gnus-tree-open group)
+        (gnus-tree-open)
         (setq gnus-summary-highlight-line-function
               'gnus-tree-highlight-article))
       ;; If the summary buffer is empty, but there are some low-scored
@@ -5612,7 +5612,7 @@ If SELECT-ARTICLES, only select those articles from GROUP."
     (or (and entry (not (eq (car entry) t))) ; Either it's active...
         (gnus-activate-group group)     ; Or we can activate it...
         (progn                          ; Or we bug out.
-          (when (equal major-mode 'gnus-summary-mode)
+          (when (derived-mode-p 'gnus-summary-mode)
             (gnus-kill-buffer (current-buffer)))
           (error
            "Couldn't activate group %s: %s"
@@ -5620,7 +5620,7 @@ If SELECT-ARTICLES, only select those articles from GROUP."
            (mm-decode-coding-string (gnus-status-message group) charset))))
 
     (unless (gnus-request-group group t)
-      (when (equal major-mode 'gnus-summary-mode)
+      (when (derived-mode-p 'gnus-summary-mode)
         (gnus-kill-buffer (current-buffer)))
       (error "Couldn't request group %s: %s"
              (mm-decode-coding-string group charset)
@@ -7257,7 +7257,7 @@ If FORCE (the prefix), also save the .newsrc file(s)."
     (when gnus-suppress-duplicates
       (gnus-dup-enter-articles))
     (when gnus-use-trees
-      (gnus-tree-close group))
+      (gnus-tree-close))
     (when gnus-use-cache
       (gnus-cache-write-active))
     ;; Remove entries for this group.
@@ -7360,7 +7360,7 @@ If FORCE (the prefix), also save the .newsrc file(s)."
       (unless gnus-single-article-buffer
         (setq gnus-article-current nil))
       (when gnus-use-trees
-        (gnus-tree-close group))
+        (gnus-tree-close))
       (gnus-async-prefetch-remove-group group)
       (when (get-buffer gnus-article-buffer)
         (bury-buffer gnus-article-buffer))
@@ -7383,9 +7383,9 @@ The state which existed when entering the ephemeral is reset."
     (unless (eq (cdr quit-config) 'group)
       (setq gnus-current-select-method
             (gnus-find-method-for-group gnus-newsgroup-name)))
-    (cond ((eq major-mode 'gnus-summary-mode)
+    (cond ((derived-mode-p 'gnus-summary-mode)
            (gnus-set-global-variables))
-          ((eq major-mode 'gnus-article-mode)
+          ((derived-mode-p 'gnus-article-mode)
            (save-current-buffer
              ;; The `gnus-summary-buffer' variable may point
              ;; to the old summary buffer when using a single
@@ -7400,7 +7400,7 @@ The state which existed when entering the ephemeral is reset."
             (gnus-configure-windows 'pick 'force)
           (gnus-configure-windows (cdr quit-config) 'force))
       (gnus-configure-windows (cdr quit-config) 'force))
-    (when (eq major-mode 'gnus-summary-mode)
+    (when (derived-mode-p 'gnus-summary-mode)
       (if (memq gnus-auto-select-on-ephemeral-exit '(next-noselect
                                                      next-unread-noselect))
           (when (zerop (cond ((eq gnus-auto-select-on-ephemeral-exit
@@ -7470,7 +7470,7 @@ The state which existed when entering the ephemeral is reset."
       (when (and gnus-use-trees
                  (gnus-buffer-exists-p buffer))
         (with-current-buffer buffer
-          (gnus-tree-close gnus-newsgroup-name)))
+          (gnus-tree-close)))
       (gnus-kill-buffer buffer))
      ;; Deaden the buffer.
      ((gnus-buffer-exists-p buffer)
@@ -7699,7 +7699,7 @@ Given a prefix, will force an `article' buffer configuration."
   "Display ARTICLE in article buffer."
   (unless (and (gnus-buffer-live-p gnus-article-buffer)
                (with-current-buffer gnus-article-buffer
-                 (eq major-mode 'gnus-article-mode)))
+                 (derived-mode-p 'gnus-article-mode)))
     (gnus-article-setup-buffer))
   (gnus-set-global-variables)
   (with-current-buffer gnus-article-buffer
@@ -7731,7 +7731,7 @@ non-nil, the article will be re-fetched even if it already present in
 the article buffer.  If PSEUDO is non-nil, pseudo-articles will also
 be displayed."
   ;; Make sure we are in the summary buffer to work around bbdb bug.
-  (unless (eq major-mode 'gnus-summary-mode)
+  (unless (derived-mode-p 'gnus-summary-mode)
     (set-buffer gnus-summary-buffer))
   (let ((article (or article (gnus-summary-article-number)))
         (all-headers (not (not all-headers))) ;Must be t or nil.
@@ -7783,7 +7783,7 @@ If SUBJECT, only articles with SUBJECT are selected.
 If BACKWARD, the previous article is selected instead of the next."
   (interactive "P")
   ;; Make sure we are in the summary buffer.
-  (unless (eq major-mode 'gnus-summary-mode)
+  (unless (derived-mode-p 'gnus-summary-mode)
     (set-buffer gnus-summary-buffer))
   (cond
    ;; Is there such an article?
@@ -12680,7 +12680,7 @@ UNREAD is a sorted list."
                  (string-match "Summary" buffer)
                  (with-current-buffer buffer
                    ;; We check that this is, indeed, a summary buffer.
-                   (and (eq major-mode 'gnus-summary-mode)
+                   (and (derived-mode-p 'gnus-summary-mode)
                         ;; Also make sure this isn't bogus.
                         gnus-newsgroup-prepared
                         ;; Also make sure that this isn't a
@@ -12815,7 +12815,7 @@ returned."
 
 (defun gnus-summary-generic-mark (n mark move unread)
   "Mark N articles with MARK."
-  (unless (eq major-mode 'gnus-summary-mode)
+  (unless (derived-mode-p 'gnus-summary-mode)
     (error "This command can only be used in the summary buffer"))
   (gnus-summary-show-thread)
   (let ((nummove