warning message with GNU compiler

[Keren Zik-Meirom]

Hello,
I am working with GNU compiler for Tornado environment (version 2.96-mips3264-010729).
I am trying to generate a warning message in case where an object of particular enumeration type is assigned something other that one of its constant, from the tests I've made I could not reproduce it.
is that possible? if so with which option?

Thanks and Regards
Keren