From d0506a912e7424ab9a7c8293784c680d0964963c Mon Sep 17 00:00:00 2001
From: Jean-Marc Lasgouttes <lasgouttes@lyx.org>
Date: Tue, 25 Jul 2017 11:51:49 +0200
Subject: [PATCH] Check whether a class is known before loading it

Fixes bug #10719.

(cherry picked from commit 15a87dd3a86235848983022ecb7927675a62d4e3)
---
 src/tex2lyx/Preamble.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/tex2lyx/Preamble.cpp b/src/tex2lyx/Preamble.cpp
index 6dcbd5097c..15b41e65cb 100644
--- a/src/tex2lyx/Preamble.cpp
+++ b/src/tex2lyx/Preamble.cpp
@@ -1937,7 +1937,7 @@ void Preamble::parse(Parser & p, string const & forceclass,
 	if (!forceclass.empty())
 		h_textclass = forceclass;
 	tc.setName(h_textclass);
-	if (!tc.load()) {
+	if (!LayoutFileList::get().haveClass(h_textclass) || !tc.load()) {
 		cerr << "Error: Could not read layout file for textclass \"" << h_textclass << "\"." << endl;
 		exit(EXIT_FAILURE);
 	}