Sometimes (in particular when using non-typesafe functions) it can be convenient to have a getter method rather than performing a potentially lengthy explicit cast.
The underlying storage type of a bitfield can be any intrinsic integer type,
but also any enumeration.
Custom storage types are supported if the following things are defined on the storage type:
- casting 0 to the storage type
- bit shift operators (in both directions)
- bitwise & operator
- bitwise ~ operator
- std::make_unsigned specialization
