configure: enforce the use of C99

diff --git a/configure.ac b/configure.ac
index 5d41df3c3eae88a398e06cafb1b3b2dee3d59a4c..bc5f6d67022e2279cffd08a3403c62e2a3f2b106 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -44,6 +44,9 @@ LT_INIT
 # Checks for programs.
 AC_PROG_CC
 AC_PROG_CC_C99
+if test x"$ac_cv_prog_cc_c99" = x"no"; then
+  AC_MSG_FAILURE([*** C99 support is mandatory])
+fi
 AC_PROG_CXX
 AM_PROG_CC_C_O
 AC_PROG_LIBTOOL