Valid to assign to field of struct in union?

[Johan Engelen via Digitalmars-d]

On Tuesday, 6 September 2016 at 17:58:44 UTC, Timon Gehr wrote:
>
> I don't think so (although your case could be made to work 
> easily enough). This seems to be accepts-invalid.

What do you think of the original example [1] in the bug report 
that uses
`mixin Proxy!i;` ?

[1] https://issues.dlang.org/show_bug.cgi?id=16471#c0