-preview=in might break code

Sat Oct 3 15:21:47 UTC 2020

On Saturday, 3 October 2020 at 14:48:48 UTC, Adam D. Ruppe wrote:
> On Saturday, 3 October 2020 at 14:10:34 UTC, Steven 
> Schveighoffer wrote:
>> What happens is, I write code that assumes some `in` parameter 
>> won't change
>
> That code is kinda already buggy since in just means you won't 
> change it, but somebody else might.

How come? I thought the current (modern) D semantics is that if 
you cast away shared the compiler can assume that no other 
contexts (threads/IRQs) modifies the object?