Reply to Sergey,

Consider following definition:

|class Node
|{
|    union
|    {
|        protected Rect _rect;
|        const struct
|        {
|            short x, y;
|            ushort width, height;
|        }
|    }
|    setRect(...) { ... }
|}
The point is to have a readonly view of data (x, y, width, height),
protected mutable view of same data (_rect), and an interface to set
it publicly (setRect).

1. Is this declaration is legal? (const and mutable definitions in one
union)
2. Is there a difference between const and invariant struct? (I guess
it

cost = "you can't chnage it"
invariant = "Will not change at all"

should)
The current implementation seems yielding undefined behavior in this
case. If I set initial const values in constructor everything works as
expected. If I set initial const values in definition, the whole union
seems to be immutable, eg. setting ``_rect`` do not have an effect.


Setting it in a decleration my put it in read only memeory or even hard code it into expressions


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