It is not too bad in languages with discriminated unions. It's also not hard to fake discriminated unions in languages without them, even if you will miss some of the niceties.

Rather than thinking of it as an enum, think of it as a list of contructors:

    class ProgramState {
        bool w, x, y, z;

        ProgramState(x, z) // implies y = true, w = true
        ProgramState(w, z) // cannot set x; implies y = false (cannot set y)
    }

In languages with discriminated unions you might even have some natural field sharing depending on how your "constructors" are written and the memory expansion isn't necessarily "exponential".