Enum template with mixin, need 'this'

[Meta via Digitalmars-d-learn]

On Wednesday, 24 December 2014 at 20:08:07 UTC, Meta wrote:
> I am curious, however, why changing `enum` to `auto` (or bool) 
> doesn't work. You said that the mixin tries to interpret the 
> expression `cast(bool)(embeddedTest.bits & <enumName>)` at 
> compile time, but I don't understand why that would be so when 
> the storage is auto and not enum. I guess mixin doesn't work 
> quite like I thought it did; it's not quite the equivalent of 
> pasting the mixed-in code.

Ok, I understand now. I missed the fact that even when it's an 
auto or a bool variable, it is CTFE-initialized because it's 
outside the constructor. I'm so close, yet so far from making 
this work.