• Andrei Alexandrescu (2/2) Jan 28 2022 I couldn't find a distinct place where this new feature is documented.
• Dennis (10/12) Jan 28 2022 The switch was introduced in 2019 in this Pull Request:

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

I couldn't find a distinct place where this new feature is documented. 
Is one out there? Thanks!

Dennis <dkorpel gmail.com> writes:

On Friday, 28 January 2022 at 16:03:17 UTC, Andrei Alexandrescu 
wrote:
 I couldn't find a distinct place where this new feature is 
 documented. Is one out there? Thanks!

The switch was introduced in 2019 in this Pull Request: 
https://github.com/dlang/dmd/pull/9817
Based on the design you discussed in your draft DIP and DConf 
2019 talk:
https://www.youtube.com/watch?v=aRvu2JGGn6E
https://gist.github.com/andralex/e5405a5d773f07f73196c05f8339435a

Apart from a few bug fixes, there hasn't been any development 
since its introduction AFAIK, so no documentation.