Eli Zaretskii wrote:
> I still think that adding a tag to the union is the cleanest solution.

I have attached a patch implementing this. I have also attached a 
slightly improved version of the one I posted before.

I am not entirely happy with the tagged union approach. There are a 
number of places where it just assumes that the union must be doing the 
right thing here. The only other possibility would be to assert. It 
does, however, solve the problem at hand.

Does either of these grab your fancy?

Andrew Stubbs