An example of weird template error messaging

[Ethan]

On Sunday, 4 August 2019 at 15:18:40 UTC, Ethan wrote:
> So let's poke at code. If you delete the constraint on 
> ObjectRefImpl, everything compiles and runs exactly like you'd 
> expect.

I should also note that if you remove that constraint and rely on 
a static assert inside ObjectRefImpl to enforce the constraint 
that the code also compiles and runs as expected.