Prefer '(evenp A)' to '(= 0 (% A 2))'

* lisp/calc/calc-comb.el (math-prime-test):
* lisp/calc/calc-keypd.el (calc-keypad-press):
* lisp/calc/calc-math.el (math-sqrt):
(math-sqrt-raw):
* lisp/calc/calc-misc.el (math-iipow):
(math-iipow-show):
* lisp/calc/calc-stat.el (calcFunc-vmedian):
* lisp/calendar/cal-tex.el (cal-tex-cursor-filofax-2week):
(cal-tex-cursor-filofax-daily):
* lisp/elec-pair.el (electric-pair-post-self-insert-function):
* lisp/emacs-lisp/checkdoc.el (checkdoc-in-example-string-p):
* lisp/emacs-lisp/eieio.el (defclass):
* lisp/emacs-lisp/ert-x.el (ert-propertized-string):
* lisp/emacs-lisp/ert.el (ert--significant-plist-keys):
(ert--plist-difference-explanation):
* lisp/emacs-lisp/helper.el (Helper-help-scroller):
* lisp/emacs-lisp/pcase.el (pcase-setq):
* lisp/files-x.el (setq-connection-local):
* lisp/gnus/gnus-uu.el (gnus-uu-post-encoded):
* lisp/gnus/message.el (message-make-in-reply-to):
* lisp/gnus/nndiary.el (nndiary-last-occurrence):
(nndiary-next-occurrence):
* lisp/mail/rfc2047.el (rfc2047-decode-region):
* lisp/play/5x5.el (5x5-draw-grid):
* lisp/play/gametree.el (gametree-compute-reduced-score):
(gametree-insert-new-leaf):
(gametree-break-line-here):
* lisp/play/zone.el (zone-fret):
* lisp/vc/ediff-ptch.el (ediff-get-patch-buffer):
* lisp/yank-media.el (yank-media--utf-16-p): Prefer '(evenp A)' to
'(= 0 (% A 2))' and variations thereof.

lisp/calc/calc-comb.el

@@ -826,8 +826,8 @@
 		       '(t))))
 		  ((not (equal n (car math-prime-test-cache)))
 		   (cond ((if (consp n)
-                              (= (% (nth 1 n) 2) 0)
+                              (evenp (nth 1 n))
-                            (= (% n 2) 0))
+                            (evenp n))
                           '(nil 2))
 			 ((if (consp n)
                               (= (% (nth 1 n) 5) 0)

lisp/calc/calc-keypd.el

@@ -411,7 +411,7 @@
     (if invhyp (calc-wrapper))  ; clear Inv and Hyp flags
     (unwind-protect
 	(cond ((or (null cmd)
-		   (= (% row 2) 0))
+		   (evenp row))
 	       (beep))
 	      ((and (> (minibuffer-depth) 0))
 	       (cond (isstring

lisp/calc/calc-math.el

@@ -402,7 +402,7 @@ If this can't be done, return NIL."
 			       (math-div (math-float num-sqrt) den-sqrt))))))
    (and (eq (car-safe a) 'float)
 	(if calc-symbolic-mode
-	    (if (= (% (nth 2 a) 2) 0)
+	    (if (evenp (nth 2 a))
 		(let ((res (cl-isqrt (nth 1 a))))
 		  (if (= (* res res) (nth 1 a))
 		      (math-make-float res (/ (nth 2 a) 2))
@@ -468,7 +468,7 @@ If this can't be done, return NIL."
      (t
       (if (null guess)
           (let ((ldiff (- (math-numdigs (nth 1 a)) 6)))
-            (or (= (% (+ (nth 2 a) ldiff) 2) 0) (setq ldiff (1+ ldiff)))
+            (or (evenp (+ (nth 2 a) ldiff)) (setq ldiff (1+ ldiff)))
             (setq guess (math-make-float (cl-isqrt
                                           (math-scale-int (nth 1 a) (- ldiff)))
                                          (/ (+ (nth 2 a) ldiff) 2)))))

lisp/calc/calc-misc.el

@@ -898,7 +898,7 @@ loaded and the keystroke automatically re-typed."
 (defun math-iipow (a n)   ; [O O S]
   (cond ((= n 0) 1)
 	((= n 1) a)
-	((= (% n 2) 0) (math-iipow (math-mul a a) (/ n 2)))
+	((evenp n) (math-iipow (math-mul a a) (/ n 2)))
 	(t (math-mul a (math-iipow (math-mul a a) (/ n 2))))))
 
 (defun math-iipow-show (a n)   ; [O O S]
@@ -906,7 +906,7 @@ loaded and the keystroke automatically re-typed."
   (let ((val (cond
 	      ((= n 0) 1)
 	      ((= n 1) a)
-	      ((= (% n 2) 0) (math-iipow-show (math-mul a a) (/ n 2)))
+	      ((evenp n) (math-iipow-show (math-mul a a) (/ n 2)))
 	      (t (math-mul a (math-iipow-show (math-mul a a) (/ n 2)))))))
     (math-working "pow" val)
     val))

lisp/calc/calc-stat.el

@@ -390,7 +390,7 @@
 	      (math-reject-arg (car p) 'anglep))
 	  (setq p (cdr p)))
 	(setq flat (sort flat 'math-lessp))
-	(if (= (% len 2) 0)
+	(if (evenp len)
 	    (math-div (math-add (nth (1- hlen) flat) (nth hlen flat)) 2)
 	  (nth hlen flat))))))
 

lisp/calendar/cal-tex.el

@@ -1295,7 +1295,7 @@ Optional EVENT indicates a buffer position to use instead of point."
     (cal-tex-b-document)
     (cal-tex-cmd "\\pagestyle" "empty")
     (dotimes (i n)
-      (if (zerop (mod i 2))
+      (if (evenp i)
           (insert "\\righthead")
         (insert "\\lefthead"))
       (cal-tex-arg
@@ -1318,7 +1318,7 @@ Optional EVENT indicates a buffer position to use instead of point."
                       (calendar-extract-year d))))))
       (insert "%\n")
       (dotimes (_jdummy 7)
-        (if (zerop (mod i 2))
+        (if (evenp i)
             (insert "\\rightday")
           (insert "\\leftday"))
         (cal-tex-arg (cal-tex-LaTeXify-string (calendar-day-name date)))
@@ -1388,7 +1388,7 @@ Optional EVENT indicates a buffer position to use instead of point."
     (cal-tex-cmd "\\pagestyle" "empty")
     (dotimes (i n)
       (dotimes (j 4)
-        (let ((even (zerop (% j 2))))
+        (let ((even (evenp j)))
           (insert (if even
                       "\\righthead"
                     "\\lefthead"))

lisp/elec-pair.el

@@ -558,7 +558,7 @@ The decision is taken by order of preference:
         ;; Backslash-escaped: no pairing, no skipping.
         ((save-excursion
            (goto-char beg)
-           (not (zerop (% (skip-syntax-backward "\\") 2))))
+           (not (evenp (skip-syntax-backward "\\"))))
          (let ((current-prefix-arg (1- num)))
            (electric-pair-post-self-insert-function)))
         ;; Skip self.

lisp/emacs-lisp/checkdoc.el

@@ -2109,7 +2109,7 @@ The text checked is between START and LIMIT."
 	(goto-char start)
 	(while (and (< (point) p) (re-search-forward "\\\\\"" limit t))
 	  (setq c (1+ c)))
-	(and (< 0 c) (= (% c 2) 0))))))
+	(and (< 0 c) (evenp c))))))
 
 (defun checkdoc-in-abbreviation-p (begin)
   "Return non-nil if point is at an abbreviation.

lisp/emacs-lisp/eieio.el

@@ -115,7 +115,7 @@ and reference them using the function `class-option'."
   (cl-check-type superclasses list)
 
   (cond ((and (stringp (car options-and-doc))
-              (/= 1 (% (length options-and-doc) 2)))
+              (evenp (length options-and-doc)))
          (error "Too many arguments to `defclass'"))
         ((and (symbolp (car options-and-doc))
               (oddp (length options-and-doc)))

lisp/emacs-lisp/ert-x.el

@@ -260,7 +260,7 @@ structure with the plists in ARGS."
                (string (let ((begin (point)))
                          (insert x)
                          (set-text-properties begin (point) current-plist)))
-               (list (unless (zerop (mod (length x) 2))
+               (list (unless (evenp (length x))
                        (error "Odd number of args in plist: %S" x))
                      (setq current-plist x))))
     (buffer-string)))

lisp/emacs-lisp/ert.el

@@ -576,7 +576,7 @@ Return nil if they are."
 
 (defun ert--significant-plist-keys (plist)
   "Return the keys of PLIST that have non-null values, in order."
-  (cl-assert (zerop (mod (length plist) 2)) t)
+  (cl-assert (evenp (length plist)) t)
   (cl-loop for (key value . rest) on plist by #'cddr
            unless (or (null value) (memq key accu)) collect key into accu
            finally (cl-return accu)))
@@ -587,8 +587,8 @@ Return nil if they are."
 Returns nil if they are equivalent, i.e., have the same value for
 each key, where absent values are treated as nil.  The order of
 key/value pairs in each list does not matter."
-  (cl-assert (zerop (mod (length a) 2)) t)
+  (cl-assert (evenp (length a)) t)
-  (cl-assert (zerop (mod (length b) 2)) t)
+  (cl-assert (evenp (length b)) t)
   ;; Normalizing the plists would be another way to do this but it
   ;; requires a total ordering on all lisp objects (since any object
   ;; is valid as a text property key).  Perhaps defining such an

lisp/emacs-lisp/helper.el

@@ -80,7 +80,7 @@
 		 (recenter))
                 ((and (or (eq continue 'backspace)
                           (eq continue ?\177))
-                      (zerop (% state 2)))
+                      (evenp state))
 		 (scroll-down))
 		(t (setq continue nil))))))))
 

lisp/emacs-lisp/pcase.el

@@ -370,7 +370,7 @@ undetected, binding variables to arbitrary values, such as nil.
   (cond
    (args
     (let ((arg-length (length args)))
-      (unless (= 0 (mod arg-length 2))
+      (unless (evenp arg-length)
         (signal 'wrong-number-of-arguments
                 (list 'pcase-setq (+ 2 arg-length)))))
     (let ((result))

lisp/files-x.el

@@ -914,7 +914,7 @@ earlier in the `setq-connection-local'.  The return value of the
 
 \(fn [VARIABLE VALUE]...)"
   (declare (debug setq))
-  (unless (zerop (mod (length pairs) 2))
+  (unless (evenp (length pairs))
     (error "PAIRS must have an even number of variable/value members"))
   (let ((set-expr nil)
         (profile-vars nil))

lisp/gnus/gnus-uu.el

@@ -2098,7 +2098,7 @@ If no file has been included, the user will be asked for a file."
 		 (make-string minlen ?-)
 		 file-name i parts
 		 (make-string
-		  (if (= 0 (% whole-len 2)) (1- minlen) minlen) ?-)))
+		  (if (evenp whole-len) (1- minlen) minlen) ?-)))
 
 	(goto-char (point-min))
 	(when (re-search-forward "^Subject: " nil t)

lisp/gnus/message.el

@@ -6035,7 +6035,7 @@ In posting styles use `(\"Expires\" (make-expires-date 30))'."
                         (while (search-forward "\"" nil t)
                           (when (prog2
                                     (backward-char)
-                                    (zerop (% (skip-chars-backward "\\\\") 2))
+                                    (evenp (skip-chars-backward "\\\\"))
                                   (goto-char (match-beginning 0)))
                             (insert "\\"))
                           (forward-char))

lisp/gnus/nndiary.el

@@ -1353,9 +1353,9 @@ all.  This may very well take some time.")
 		       (max (cond ((= month 2)
 				   (if (date-leap-year-p year) 29 28))
 				  ((<= month 7)
-				   (if (zerop (% month 2)) 30 31))
+				   (if (evenp month) 30 31))
 				  (t
-				   (if (zerop (% month 2)) 31 30))))
+				   (if (evenp month) 31 30))))
 		       (doms dom-list)
 		       (dows dow-list)
 		       day days)
@@ -1456,9 +1456,9 @@ all.  This may very well take some time.")
 		       (max (cond ((= month 2)
 				   (if (date-leap-year-p year) 29 28))
 				  ((<= month 7)
-				   (if (zerop (% month 2)) 30 31))
+				   (if (evenp month) 30 31))
 				  (t
-				   (if (zerop (% month 2)) 31 30))))
+				   (if (evenp month) 31 30))))
 		       (doms dom-list)
 		       (dows dow-list)
 		       day days)

lisp/mail/rfc2047.el

@@ -1076,7 +1076,7 @@ other than `\"' and `\\' in quoted strings."
 		(while (search-forward "\"" end t)
 		  (when (prog2
 			    (backward-char)
-			    (zerop (% (skip-chars-backward "\\\\") 2))
+			    (evenp (skip-chars-backward "\\\\"))
 			  (goto-char (match-beginning 0)))
 		    (insert "\\"))
 		  (forward-char))

lisp/play/5x5.el

@@ -312,7 +312,7 @@ Quit current game           \\[5x5-quit-game]"
 		  (forward-char  (+ 1 (/ (1+ 5x5-x-scale) 2)))
 		  (dotimes (x 5x5-grid-size)
 		    (when (5x5-cell solution-grid y x)
-		      (if (= 0 (mod 5x5-x-scale 2))
+		      (if (evenp 5x5-x-scale)
 			  (progn
 			    (insert "()")
 			    (delete-region (point) (+ (point) 2))

lisp/play/gametree.el

@@ -347,7 +347,7 @@ Subnodes which have been manually scored are honored."
         ;; be either a leaf child, or a subheading.
         (let ((running gametree-default-score)
               (minmax
-               (if (= 0 (mod (gametree-current-branch-ply) 2))
+               (if (evenp (gametree-current-branch-ply))
                    'max 'min)))
           (while (and (not (eobp))
                       (= 0 (gametree-current-branch-depth))) ;handle leaves
@@ -395,7 +395,7 @@ depth AT-DEPTH or smaller is found."
                              (gametree-current-branch-ply)))))
       (goto-char (1- (point)))
       (insert "\n")
-      (insert (format (if (= 0 (mod starting-plies 2))
+      (insert (format (if (evenp starting-plies)
                           gametree-full-ply-format
                         gametree-half-ply-format)
                       (/ starting-plies 2))))))
@@ -450,7 +450,7 @@ only work of Black's moves are explicitly numbered, for instance
                                    gametree-full-ply-regexp "\\|"
                                    gametree-half-ply-regexp "\\)")))
           (progn
-            (insert (format (if (= 0 (mod (gametree-looking-at-ply) 2))
+            (insert (format (if (evenp (gametree-looking-at-ply))
                                 gametree-full-ply-format
                               gametree-half-ply-format)
                             (/ (gametree-looking-at-ply) 2)))

lisp/play/zone.el

@@ -454,7 +454,7 @@ run a specific program.  The program must be a member of
     (dotimes (i 20)
       (goto-char pos)
       (delete-char 1)
-      (insert (if (= 0 (% i 2)) hmm c-string))
+      (insert (if (evenp i) hmm c-string))
       (zone-park/sit-for wbeg (setq wait (* wait 0.8))))
     (delete-char -1) (insert c-string)))
 

lisp/vc/ediff-ptch.el

@@ -549,7 +549,7 @@ an optional argument, then use it."
 
     (cond ((ediff-buffer-live-p patch-buf))
 	  ;; even prefix arg: patch in buffer
-	  ((and (integerp arg) (eq 0 (mod arg 2)))
+	  ((and (integerp arg) (evenp arg))
 	   (setq patch-buf (ediff-prompt-for-patch-buffer)))
 	  ;; odd prefix arg: get patch from a file
 	  ((and (integerp arg) (oddp arg))

lisp/yank-media.el

@@ -172,7 +172,7 @@ non-supported selection data types."
     data)))
 
 (defun yank-media--utf-16-p (data)
-  (and (zerop (mod (length data) 2))
+  (and (evenp (length data))
        (let ((stats (vector 0 0)))
          (dotimes (i (length data))
            (when (zerop (elt data i))