Fixing it on the opclass is not an option for BRIN. We designed BRIN opclasses extensible using extra SQL level support functions and operators. It is possible to support point datatype using box vs point operators. Doing so would lead to wrong results, because point operators use FP macros, but box_contain_pt() doesn't.
You still can workaround this problem in opclass. For instance, you can assign different strategy number for this case. And call another support function instead of overlap operator in brin_inclusion_consistent. For sure, this would be a kluge.
GiST opclass could be more clean and extensible, if we wouldn't have those macros.
In my opinion it would be cool remove FP macros. I see absolutely no sense in them. But since it break compatibility it would be quite hard though.
------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
