+#error "\
+\n\
+\n\
+ AFB_BINDING_VERSION should be defined before including <afb/afb-binding.h>\n\
+ AFB_BINDING_VERSION defines the version of binding that you use.\n\
+ Currently the version to use is 3 (older versions: 1 is obsolete, 2 is legacy).\n\
+ Consider to add one of the following define before including <afb/afb-binding.h>:\n\
+\n\
+ #define AFB_BINDING_VERSION 3\n\
+\n\
+"
+#else
+# if AFB_BINDING_VERSION == 1
+# warning "Using binding version 1, consider to switch to version 3"
+# endif
+# if AFB_BINDING_VERSION == 2
+# warning "Using binding version 2, consider to switch to version 3"
+# endif