Create a Variant_Base object holding the same alternative (if any) held by the specified original object. If this Variant_Base is allocator-aware, the specified allocator is used to supply memory. If the original object is not valueless by exception, the contained value is copy/move constructed from the contained value of original. All alternatives shall be copy/move constructible.
Declared in <bslstl_variant.h>
Variant_Base(
std::allocator_arg_t,
allocator_type allocator,
Variant const& original);