From 37c34c5ca98a31669144a7119068edf96d68261c Mon Sep 17 00:00:00 2001
From: Jean-Marc Lasgouttes <lasgouttes@lyx.org>
Date: Mon, 11 Oct 2021 14:31:58 +0200
Subject: [PATCH] Fixup c52049bb83d: -Werror is needed to test for warning
 flags

At least on my old clang++, this is required.

Fixes bug #12391.
---
 config/lyxinclude.m4 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/config/lyxinclude.m4 b/config/lyxinclude.m4
index 0b41e21e5a..afad2bd919 100644
--- a/config/lyxinclude.m4
+++ b/config/lyxinclude.m4
@@ -391,7 +391,7 @@ if test x$GXX = xyes; then
       dnl note that g++ always accepts -Wno-xxx, even when -Wxxx is an error.
       AC_LANG_PUSH(C++)
       AX_CHECK_COMPILE_FLAG([-Wdeprecated-copy],
-	[AM_CXXFLAGS="$AM_CXXFLAGS -Wno-deprecated-copy"])
+	[AM_CXXFLAGS="$AM_CXXFLAGS -Wno-deprecated-copy"], [], [-Werror])
       AC_LANG_POP(C++)
     fi
   case $gxx_version in