build: enable -Werror=gnu

vasild · vasild · commit a30b0a24e97e · 2020-05-05T14:47:59.000+02:00
Stop the build if a warning is emitted due to `-Wgnu` and `--enable-werror` has been used. As usual - this would help notice such a warning that is about to be introduced in new code. This is a followup to #18088 build: ensure we aren't using GNU extensions
diff --git a/configure.ac b/configure.ac
@@ -338,6 +338,7 @@ if test "x$enable_werror" = "xyes"; then
   if test "x$CXXFLAG_WERROR" = "x"; then
     AC_MSG_ERROR("enable-werror set but -Werror is not usable")
   fi
+  AX_CHECK_COMPILE_FLAG([-Werror=gnu],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=gnu"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Werror=vla],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=vla"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Werror=switch],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=switch"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Werror=thread-safety-analysis],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=thread-safety-analysis"],,[[$CXXFLAG_WERROR]])
