I realized that LiteC didn't support unions, and also remembered enough to know that unions may have special properties that would keep me from simply replacing them with a like struct.

In your second example, are you actually creating a rogue "data3" member?! Confusing, because the LiteC S_UNION hasn't been defined yet, and when you do define it, it doesn't contain "data3". I wouldn't have thought that "s_union.data3 = 3.14" would be allowed at that place in the code. I also would have never thought that "s_union.data3" would serve as phantom member. Am I understanding this correctly?... and thanks much for the info : )