Make sure Clang reports warnings as errors in test

diff --git a/m4/pdns_pie.m4 b/m4/pdns_pie.m4
index 9d64e48a795f58c5dd59b9dadf0e04ee7e3db1c9..ef41be5472414b551df8ba36283cef3b5f6ef7a5 100644 (file)
--- a/m4/pdns_pie.m4
+++ b/m4/pdns_pie.m4
@@ -19,6 +19,7 @@ dnl <http://www.gnu.org/licenses/>.
 dnl
 
 AC_DEFUN([AC_CC_PIE],[
+    AC_REQUIRE([gl_UNKNOWN_WARNINGS_ARE_ERRORS])
     PIE_CFLAGS=
     PIE_LDFLAGS=
     case "$host" in