>From 34e58334d86d10e489d6f77179a310c88f019bc1 Mon Sep 17 00:00:00 2001
From: Ikumi Keita <ikumi@ikumi.que.jp>
Date: Wed, 20 Jan 2021 17:45:31 +0900
Subject: [PATCH] Prevent inadvertent destruction of list variable

* latex.el (LaTeX-common-initialization): Apply `copy-sequence' to the
last argument of `delete-dups'+`append'.
---
 latex.el | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/latex.el b/latex.el
index 6a8b2fd5..b4fd7d38 100644
--- a/latex.el
+++ b/latex.el
@@ -6219,7 +6219,10 @@ function would return non-nil and `(match-string 1)' would return
 
   (setq-local TeX-auto-full-regexp-list
               (delete-dups (append LaTeX-auto-regexp-list
-                                   plain-TeX-auto-regexp-list)))
+                                   ;; Prevent inadvertent destruction
+                                   ;; of `plain-TeX-auto-regexp-list'.
+                                   (copy-sequence
+                                    plain-TeX-auto-regexp-list))))
 
   (LaTeX-set-paragraph-start)
   (setq paragraph-separate
-- 
2.30.0