Re: [boost] [variant] Maintainer

Larry Evans wrote:

Thanks Peter.

To be explicit:

tuple<> t0;

would be allowed, but:

variant<> v0;

wouldn't compile because there are "zero valid values" in a variant<>?

Yes; you can use the type variant<> but you can't declare a variable of it. N4542 says variant<> A variant without alternatives cannot be constructed; it is otherwise an allowed type. It is easier to allow it than to forbid it. which is consistent with variant being a sum type without an extra empty state (same as boost::variant). For a variant that has an extra empty state, one would expect variant<> to be instantiable and always empty.