id summary reporter owner description type status milestone component version severity resolution keywords cc 3364 terminals are constant after passing through proto::flatten and fusion::fold maurizio.vitale@… Eric Niebler I'm forced to use the code in the section marked with #if BUG while I would expect to be able to use the version in the #else branch of the same conditional. Terminals are non-const, hence the casting const away in assignments shouldn't be needed. Bugs closed Boost 1.40.0 proto Boost 1.39.0 Problem fixed