what exactly does cast(shared) and cast away shared do?

[Petar]

On Tuesday, 16 June 2020 at 08:07:41 UTC, Simen Kjærås wrote:
> [..] A DIP* has been accepted that will limit your ability to 
> do dangerous things in this case, but it is not yet implemented.
>
>
> * 
> https://github.com/dlang/DIPs/blob/master/DIPs/accepted/DIP1024.md
>
> --
>   Simen

It has been implemented (modulo bugs [1][2]) as of:

https://github.com/dlang/dmd/pull/10209
https://github.com/dlang/dmd/pull/11239

[1]: https://issues.dlang.org/show_bug.cgi?id=20195
[2]: https://issues.dlang.org/show_bug.cgi?id=20908