Remove use of boost::optional about first_order_logic_prover HOT 3 CLOSED

Does std::experimental::optional has same issue? Please give me the detailed description.
BTW, an implementation of WG21/N4081 aiming to be simpler and more reliable than libstdc++/libc++'s std::experimental::optional is under construction and would be committed in next revision (implementation completed but not tested yet).

from first_order_logic_prover.

Don't know about std::experimental::optional, the only problem is that boost::optional allow implicit conversion of bool, so my code relying on boost::optional is extremely fraudulent to refactor change, such as refactoring some bool to some enum type.

from first_order_logic_prover.

std::experimental::optional dont have this problem because it's explicit constructor.

from first_order_logic_prover.