Fixup c52049bb83d: -Werror is needed to test for warning flags

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

Fixes bug #12391.

diff --git a/config/lyxinclude.m4 b/config/lyxinclude.m4
index 0b41e21e5a818b999442af559714fc4437b12919..afad2bd9197cd3a3c105aa545c2369e1c750634b 100644 (file)
--- 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