On Borrow Checking

[Richard (Rikki) Andrew Cattermole]

On 13/05/2025 12:34 AM, Timon Gehr wrote:
> On 5/12/25 13:52, Richard (Rikki) Andrew Cattermole wrote:
>>
>> It has everything to do with @safe, that is where the mechanical 
>> checks exist.
>>
>> You do not need the escape set (``scope``), if you do not have the 
>> mechanical checks, and where you have an escape hatch (``@trusted`` 
>> and ``@system``), these are intentionally not turned on.
> 
> Even in `@system` code you cannot assign an `int` to an `int*`, you have 
> to use an explicit cast. I don't think it is true that just because 
> `@system` does not give you memory safety guarantees it will therefore 
> be expected that features do not work at all.
> 
> This is a design decision, and I think Manu's and Walter's expectations 
> are more reasonable than what the compiler actually does.

Right, perhaps if it was a different design, say unsafe blocks I'd agree 
with what Manu is saying.

Unfortunately the current design has a valid set of tradeoffs.

And from experience you must have some sort of escape hatch, and that is 
``@trusted`` and ``@system`` currently, enforcing ``scope`` there would 
make it unusable.