After building SNMP++ v3.6.6 with OPTION_THREADS disabled, I encounter build errors of the dependent AGENT++ v4.7.2 build:
include/agent_pp/request.h:904:17: error: use of undeclared identifier 'Synchronized'
include/agent_pp/request.h:904:31: error: no type named 'TryLockResult' in 'Snmp_pp::SnmpSynchronized'
Option a) this is an actual bug.
Option b) AGENT++ is just not supposed to be built without support for threads.
In this case it would be nice to have an #error directive set by AGENT++'s preprocessor with a corresponding error message.