Rebooting the __metada/__mutable discussion

[Bruce Carneal]

On Sunday, 10 April 2022 at 13:02:07 UTC, Zach Tollen wrote:
> On Sunday, 10 April 2022 at 05:41:36 UTC, Bruce Carneal wrote:
>> I view 1035 as a mechanism to extend the reach of @safe, to 
>> reduce the load on conscientious code reviewers.
>
> One aspect of DIP1035 I'm confused about in this regard is item 
> (1) in the [proposed 
> changes](https://github.com/dlang/DIPs/blob/72f41cffe68ff1f2d4c033b5728ef37e282461dd/DIPs/DIP1035.md#proposed-changes): "An aggregate with at least one @system field is an unsafe type."
>
> This concerns me because it seems like it would extend the 
> reach of *@system*, rather than *@safe*. It seems like having 
> one @system variable would contaminate the whole structure so 
> that you always had to use @trusted just to do anything with it.
>

Yes, at what cost do we achieve additional (automated) safety?  I 
have no 1035 improvements to offer, and support it as is, but I 
think that your concern here is on point.