Enhancements can enable memory-safe reference counting

[tsbockman]

On Friday, 14 May 2021 at 00:45:09 UTC, tsbockman wrote:
> ```D
> class D { }
> ```
> ```
> a: ACCEPTS INVALID: static D = return D
> ```

I reduced this once and filed an issue for it, since it is the 
worst of the bunch:

"Template breaks return annotation for class reference returned 
by struct method"
https://issues.dlang.org/show_bug.cgi?id=22528