AC_CHECK_LIB(adns,adns_init)
REQUIRE_HEADER([adns.h])
+AC_CHECK_FUNCS([fmemopen funopen])
+
+dnl gcc 4.9.2 (jessie) requires -std=gnu11 to cope with for (int i=...
+dnl but we do not want to pass that everywhere because we don't want
+dnl to nail down the C dialect this way. Why oh why oh why.
+m4_define([for_gcc_std],[
+void x(void) { for (int i=0; i<1; i++) { } }
+])
+AC_CACHE_CHECK([required gcc -std flag],[secnet_cv_gcc_std_flag],[
+ secnet_cv_gcc_std_flag=""
+ AC_COMPILE_IFELSE([AC_LANG_SOURCE(for_gcc_std)],[],[
+ old_cflags="$CFLAGS"
+ CFLAGS="$CFLAGS -std=gnu11"
+ AC_COMPILE_IFELSE([AC_LANG_SOURCE(for_gcc_std)],[
+ secnet_cv_gcc_std_flag=" -std=gnu11"
+ ],[
+ AC_MSG_RESULT([failure!])
+ AC_MSG_ERROR([cannot get test program to compile],1)
+ ])
+ CFLAGS="$old_cflags"
+ ])
+])
+CFLAGS="$CFLAGS$secnet_cv_gcc_std_flag"
+
AC_MSG_NOTICE([Checking requirements for IPv6 support...])
enable_ipv6=true
m4_define(NO_IPV6,[enable_ipv6=false])