Opaque type (struct) with a static immutable fails to compile without constructor - why?

[frankp]

On Thursday, 4 March 2021 at 14:54:11 UTC, frankp wrote:
> I give up. This makes no sense. I just accept this is the work 
> of gremlins. I revert to a plain alias and an enum.
>
> Sorry for wasting your time.

Not gremlins after all. It was simply a matter of the compiler 
pointing to the wrong line. Everything makes sense now. Anyways, 
thanks for your help.