>From f9f118d46a065e9a1482300d6879a7d0163921f2 Mon Sep 17 00:00:00 2001
From: "Basil L. Contovounesios" <contovob@tcd.ie>
Date: Wed, 18 Apr 2018 17:45:35 +0100
Subject: [PATCH 2/2] Minor simple.el simplifications (bug#31211)

* lisp/simple.el (kill-append, push-mark, pop-mark):
Simplify conditionals and surrounding code.
---
 lisp/simple.el | 48 +++++++++++++++++++++++-------------------------
 1 file changed, 23 insertions(+), 25 deletions(-)

diff --git a/lisp/simple.el b/lisp/simple.el
index f7f8da87ad..0d9abf342b 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -4418,18 +4418,18 @@ kill-append
 If `interprogram-cut-function' is set, pass the resulting kill to it."
   (let* ((cur (car kill-ring)))
     (kill-new (if before-p (concat string cur) (concat cur string))
-	      (or (= (length cur) 0)
-		  (equal nil (get-text-property 0 'yank-handler cur))))
-    (when (and kill-append-merge-undo (not buffer-read-only))
-      (let ((prev buffer-undo-list)
-            (next (cdr buffer-undo-list)))
-        ;; find the next undo boundary
-        (while (car next)
-          (pop next)
-          (pop prev))
-        ;; remove this undo boundary
-        (when prev
-          (setcdr prev (cdr next)))))))
+              (or (string= cur "")
+                  (null (get-text-property 0 'yank-handler cur)))))
+  (when (and kill-append-merge-undo (not buffer-read-only))
+    (let ((prev buffer-undo-list)
+          (next (cdr buffer-undo-list)))
+      ;; Find the next undo boundary.
+      (while (car next)
+        (pop next)
+        (pop prev))
+      ;; Remove this undo boundary.
+      (when prev
+        (setcdr prev (cdr next))))))
 
 (defcustom yank-pop-change-selection nil
   "Whether rotating the kill ring changes the window system selection.
@@ -5703,20 +5703,18 @@ push-mark
 purposes.  See the documentation of `set-mark' for more information.
 
 In Transient Mark mode, activate mark if optional third arg ACTIVATE non-nil."
-  (unless (null (mark t))
-    (setq mark-ring (cons (copy-marker (mark-marker)) mark-ring))
+  (when (mark t)
+    (push (copy-marker (mark-marker)) mark-ring)
     (let ((tail (nthcdr (1- mark-ring-max) mark-ring)))
       (when (cdr tail)
         (set-marker (cadr tail) nil)
         (setcdr tail ()))))
   (set-marker (mark-marker) (or location (point)) (current-buffer))
-  ;; Now push the mark on the global mark ring.
-  (if (and global-mark-ring
-	   (eq (marker-buffer (car global-mark-ring)) (current-buffer)))
-      ;; The last global mark pushed was in this same buffer.
-      ;; Don't push another one.
-      nil
-    (setq global-mark-ring (cons (copy-marker (mark-marker)) global-mark-ring))
+  ;; Don't push the mark on the global mark ring if the last global
+  ;; mark pushed was in this same buffer.
+  (unless (and global-mark-ring
+               (eq (marker-buffer (car global-mark-ring)) (current-buffer)))
+    (push (copy-marker (mark-marker)) global-mark-ring)
     (let ((tail (nthcdr (1- global-mark-ring-max) global-mark-ring)))
       (when (cdr tail)
         (set-marker (cadr tail) nil)
@@ -5732,10 +5730,10 @@ pop-mark
 Does not set point.  Does nothing if mark ring is empty."
   (when mark-ring
     (setq mark-ring (nconc mark-ring (list (copy-marker (mark-marker)))))
-    (set-marker (mark-marker) (+ 0 (car mark-ring)) (current-buffer))
-    (move-marker (car mark-ring) nil)
-    (if (null (mark t)) (ding))
-    (setq mark-ring (cdr mark-ring)))
+    (set-marker (mark-marker) (marker-position (car mark-ring)))
+    (set-marker (car mark-ring) nil)
+    (unless (mark t) (ding))
+    (pop mark-ring))
   (deactivate-mark))
 
 (define-obsolete-function-alias
-- 
2.17.0