From cc1d4882211e26f5c48d1f57dc41c873eb04e397 Mon Sep 17 00:00:00 2001
From: Hironori Kitagawa <h_kitagawa2001@yahoo.co.jp>
Date: Sun, 14 May 2023 16:31:23 +0900
Subject: [PATCH] error message when not used in Lua*TeX

---
 src/luatexja-core.sty | 18 ++++++++++++------
 src/luatexja.sty      |  2 --
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/src/luatexja-core.sty b/src/luatexja-core.sty
index b0c5c80..12a7a09 100644
--- a/src/luatexja-core.sty
+++ b/src/luatexja-core.sty
@@ -61,13 +61,24 @@
 \expandafter\ifx\csname RequirePackage\endcsname\relax %<*!LaTeX>
   \expandafter\let\csname ifltj@in@latex\expandafter\endcsname
     \csname iffalse\endcsname
+  \endlinechar=13 %
+  \input infwarerr.sty
+  \endlinechar=-1 %
 \else                           %<*LaTeX>
   \expandafter\let\csname ifltj@in@latex\expandafter\endcsname
     \csname iftrue\endcsname
   \NeedsTeXFormat{LaTeX2e}
   \ProvidesPackage{luatexja-core}[2023-04-06 Core of LuaTeX-ja]
+  \endlinechar=13 %
+  \RequirePackage{infwarerr}
+  \endlinechar=-1 %
 \fi                             %</LaTeX>
 
+%% Check if LuaTeX is used
+\expandafter\ifx\csname directlua\endcsname\relax
+  \@PackageError{luatexja-core}{This package requires Lua(HB)(La)TeX}{}
+\expandafter\endinput\fi\relax
+
 %% Load prerequisite packages.
 \endlinechar=13 %
 \newif\ifltj@everyhook@avail\ltj@everyhook@availfalse
@@ -89,12 +100,7 @@
 \fi                             %</LaTeX>
 \endlinechar=-1 %
 
-%% Check if LuaTeX is used
-\ltx@LocalExpandAfter\ifx\csname directlua\endcsname\relax
-  % Loading is silently aborted, since the notice of the wrong
-  % engine is already shown in luaotfload.
-  \ltj@core@AtEnd
-\expandafter\endinput\fi\relax
+\directlua{require('ltj-unicode-ccfix.lua')}% catcode of ideographs
 
 %% Check LuaTeX version.
 \ifnum\luatexversion<110
diff --git a/src/luatexja.sty b/src/luatexja.sty
index 5d04d1d..bbdff92 100644
--- a/src/luatexja.sty
+++ b/src/luatexja.sty
@@ -50,8 +50,6 @@
   \ProcessOptions\relax
 \fi                             %</LaTeX>
 
-\directlua{require('ltj-unicode-ccfix.lua')}% catcode of ideographs
-
 %% Load all sub-packages.
 \ifltj@in@latex                 %<*LaTeX>
   %% \RequirePackage{expl3} needed if the version of l3kernel is v6111
-- 
2.11.0