smhasher2 is not fragile at all. The rain test api functions are static in a .cpp. This will not work anywhere else than in smhasher3 with its special wrappers.

smhasher2 is not fragile at all. The rain test api functions are static in a .cpp. This will not work anywhere else than in smhasher3 with its special wrappers. You need to put them in headers if you want them static inline.