From ec3e24819c5e2ec2df1f51bd3cb70ac4e598b9d6 Mon Sep 17 00:00:00 2001
From: Allen Li <darkfeline@felesatra.moe>
Date: Wed, 24 Oct 2018 20:48:15 -0600
Subject: [PATCH 2/2] Add setter for xref-marker-ring-length

* etc/NEWS: Document change
* lisp/progmodes/xref.el (xref-marker-ring-length): Add setter
---
 etc/NEWS               |  7 +++++++
 lisp/progmodes/xref.el | 16 ++++++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index c67b13205c..f9a9fa6afc 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -113,6 +113,13 @@ option 'vc-hg-symbolic-revision-styles' to the value '("{rev}")'.
 ---
 ** shadowfile.el has been rewritten to support Tramp file names.
 
+** xref
+
++++
+*** Setter added for 'xref-marker-ring-length'.
+Previously, setting 'xref-marker-ring-length' would only take effect
+if set before `xref.el` was loaded.
+
 
 * New Modes and Packages in Emacs 26.2
 
diff --git a/lisp/progmodes/xref.el b/lisp/progmodes/xref.el
index abb2a93425..eaa4014145 100644
--- a/lisp/progmodes/xref.el
+++ b/lisp/progmodes/xref.el
@@ -317,8 +317,12 @@ xref--search-property
 ;;; Marker stack  (M-. pushes, M-, pops)
 
 (defcustom xref-marker-ring-length 16
-  "Length of the xref marker ring."
-  :type 'integer)
+  "Length of the xref marker ring.
+If this variable is not set through Customize, you must call
+‘xref-set-marker-ring-length’ for changes to take effect."
+  :type 'integer
+  :initialize #'custom-initialize-default
+  :set #'xref-set-marker-ring-length)
 
 (defcustom xref-prompt-for-identifier '(not xref-find-definitions
                                             xref-find-definitions-other-window
@@ -354,6 +358,14 @@ xref-after-return-hook
 (defvar xref--marker-ring (make-ring xref-marker-ring-length)
   "Ring of markers to implement the marker stack.")
 
+(defun xref-set-marker-ring-length (var val)
+  "Set ‘xref-marker-ring-length’.
+VAR is the symbol ‘xref-marker-ring-length’ and VAL is the new
+value."
+  (set-default var val)
+  (if (ring-p xref--marker-ring)
+      (ring-resize xref--marker-ring val)))
+
 (defun xref-push-marker-stack (&optional m)
   "Add point M (defaults to `point-marker') to the marker stack."
   (ring-insert xref--marker-ring (or m (point-marker))))
-- 
2.19.1.568.g152ad8e336-goog