DIP1000 scope inference

[Dukc]

On Wednesday, 26 October 2022 at 08:03:37 UTC, Walter Bright 
wrote:
> On 10/24/2022 6:35 PM, Steven Schveighoffer wrote:
>> In a `@trusted` function today, without dip1000, the above is 
>> perfectly reasonable and not invalid. Will dip1000 make it 
>> corrupt memory?
>
> A very good question. Clearly, having code work when it is 
> @safe, but cause memory corruption when it is marked @trusted, 
> is the wrong solution. This should never happen. I'm not sure 
> what the solution should be here.

It's not quite exactly that. The code in question fails with 
`@safe`.

The problem is that Steven's `@trusted` code not only happens to 
work, but is defined behaviour without dip1000, yet undefined 
behaviour with `-preview=dip1000`.

My proposal: disable local variable `scope` inference for 
`@system` and `@trusted` code. This has the downside that it's 
difficult to test whether the implementation really turns the 
inference off. But unless we're ready to ditch `scope` inference 
altogether I can't come up with anything better.