Disabling other ops should be allowed

[schveiguy]

Right now, I can disable opIndex. But for unions with pointers in them, I want to disable ALL operations except dereferencing and assignment. However, even though it appears the code should honor any DisableOpAttribute, I can't build them because the struct is private.

I thought of creating a RefTo type struct, but that doesn't work, because I can't initialize the TaggedAlgebraic with a raw pointer (functionality which I want to keep).

Alternatively, if there was a way to say I only want to call @safe calls in any possible case, then I would be for that as well. This is in general what I'm trying to achieve.