bsl::variant::variant

Create a variant object whose contained value is direct‐initialized from the specified t. The alternative selected is the best match among all alternatives for which the expression t_ALT_TYPE x[]= {std::forward<t_TYPE>(t)}; is well formed, and this constructor participates in overload resolution only if there is a unique best matching alternative and that alternative is constructible from t. If this variant is allocator‐aware, the specified allocator is used to supply memory. Note that the cv‐qualification of an alternative type does not affect how well the alternative type matches an argument type.