From 00ce1f873ca68d3d8126c77126e1de7f43a24ef6 Mon Sep 17 00:00:00 2001
From: Yukai Chou <muzimuzhi@gmail.com>
Date: Tue, 29 Oct 2024 05:19:23 +0800
Subject: [PATCH] Skip mapping over undeclared `\g__hook_<hook>_code_prop`
 (#1513)

---
 base/changes.txt |  4 ++++
 base/lthooks.dtx | 27 ++++++++++++++++++---------
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/base/changes.txt b/base/changes.txt
index c5708c81a..69d5470e5 100644
--- a/base/changes.txt
+++ b/base/changes.txt
@@ -6,6 +6,10 @@ to completeness or accuracy and it contains some references to files that are
 not part of the distribution.
 ================================================================================
 
+2024-10-29  Yukai Chou <muzimuzhi@gmail.com>
+	* lthooks.dtx (subsection{Setting rules for hooks code}):
+	Skip mapping over undeclared \g__hook_<hook>_code_prop (gh/1513).
+
 2024-10-27  Marcel Krüger  <Marcel.Krueger@latex-project.org>
 	* lttagging.dtx
 	Change tagging sockets with two arguments to drop the first argument
diff --git a/base/lthooks.dtx b/base/lthooks.dtx
index c37e01e6a..abf3a9a49 100644
--- a/base/lthooks.dtx
+++ b/base/lthooks.dtx
@@ -32,7 +32,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{lthooks.dtx}
-             [2024/10/21 v1.1j LaTeX Kernel (hooks)]
+             [2024/10/29 v1.1k LaTeX Kernel (hooks)]
 % \iffalse
 %
 \documentclass{l3doc}
@@ -6174,6 +6174,8 @@
       }
 %    \end{macrocode}
 %
+% \changes{v1.1k}{2024/10/29}
+%         {Skip mapping over undeclared \cs{g_@@_\meta{hook}_code_prop} (gh/1513)}
 %    \begin{macrocode}
     \@@_if_usable:nF {#1}
       { \@@_log_line:x { The~hook~is~not~declared. } }
@@ -6183,7 +6185,9 @@
       { #2 { The~hook~is~empty } }
       {
         \@@_log_line:x { Code~chunks: }
-        \prop_if_empty:cTF { g_@@_#1_code_prop }
+        \bool_lazy_or:nnTF
+          { ! \prop_if_exist_p:c { g_@@_#1_code_prop } }
+          { \prop_if_empty_p:c { g_@@_#1_code_prop } }
           { \@@_log_line_indent:x { --- } }
           {
             \prop_map_inline:cn { g_@@_#1_code_prop }
@@ -6445,19 +6449,24 @@
 %   |#2|${}={}$\meta{label_1}\verb=|=\meta{label_2},
 %   and |#3|${}={}$\meta{hook} (the latter may be the argument |#1| to
 %   \cs{@@_list_rules:nn}, or \texttt{??} if it is a default rule).
+% \changes{v1.1k}{2024/10/29}
+%         {Skip mapping over undeclared \cs{g_@@_\meta{hook}_code_prop} (gh/1513)}
 %    \begin{macrocode}
 \cs_new_protected:Npn \@@_list_rules:nn #1 #2
   {
-    \cs_set_protected:Npn \@@_tmp:w ##1 ##2 ##3 {#2}
-    \prop_map_inline:cn { g_@@_#1_code_prop }
+    \prop_if_exist:cT { g_@@_#1_code_prop }
       {
+        \cs_set_protected:Npn \@@_tmp:w ##1 ##2 ##3 {#2}
         \prop_map_inline:cn { g_@@_#1_code_prop }
           {
-            \@@_if_label_case:nnnnn {##1} {####1}
-              { \prop_map_break: }
-              { \@@_list_one_rule:nnn {##1} {####1} }
-              { \@@_list_one_rule:nnn {####1} {##1} }
-                  {#1}
+            \prop_map_inline:cn { g_@@_#1_code_prop }
+              {
+                \@@_if_label_case:nnnnn {##1} {####1}
+                  { \prop_map_break: }
+                  { \@@_list_one_rule:nnn {##1} {####1} }
+                  { \@@_list_one_rule:nnn {####1} {##1} }
+                      {#1}
+              }
           }
       }
   }