From c6bd2f6d6959ca72845f127ef526fbbca398aed2 Mon Sep 17 00:00:00 2001
From: jfbu <jfbu@free.fr>
Date: Sun, 13 Jun 2021 18:34:06 +0200
Subject: [PATCH] Fix #9305 LaTeX: backslash in sphinxupquote error with
 Japanese

---
 CHANGES                                  | 2 ++
 sphinx/texinputs/sphinxlatexliterals.sty | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/CHANGES b/CHANGES
index fb19776cbf2..e75e38debcf 100644
--- a/CHANGES
+++ b/CHANGES
@@ -101,6 +101,8 @@ Bugs fixed
 * #9330: changeset domain: :rst:dir:`versionchanged` with contents being a list
   will cause error during pdf build
 * #9313: LaTeX: complex table with merged cells broken since 4.0
+* #9305: LaTeX: backslash may cause Improper discretionary list pdf build error
+  with Japanese engines
 
 Testing
 --------
diff --git a/sphinx/texinputs/sphinxlatexliterals.sty b/sphinx/texinputs/sphinxlatexliterals.sty
index 4d0312fc653..d2ba89ea73f 100644
--- a/sphinx/texinputs/sphinxlatexliterals.sty
+++ b/sphinx/texinputs/sphinxlatexliterals.sty
@@ -765,7 +765,8 @@
       % break at . , ; ? ! /
       \sphinxbreaksviaactive
       % break also at \
-      \let\sphinx@textbackslash\textbackslash
+      \setbox8=\hbox{\textbackslash}%
+      \def\sphinx@textbackslash{\copy8}%
       \let\textbackslash\sphinxtextbackslash
       % by default, no continuation symbol on next line but may be added
       \let\sphinxafterbreak\sphinxafterbreakofinlineliteral