On Borrow Checking

[Lance Bachmeier]

On Saturday, 17 May 2025 at 10:05:13 UTC, claptrap wrote:
> On Wednesday, 30 April 2025 at 02:58:37 UTC, Walter Bright 
> wrote:
>> On 4/29/2025 6:26 PM, jmh530 wrote:
>>
>>
>> We spent a considerable time thinking about safe 
>> reference-counting. We could not find a way around its 
>> considerable performance penalties, and its unsafety, and so 
>> abandoned it.
>
> Why is safe ref counting not feasible with D?
>
> Wouldn't the fact that most data is thread local in D mitigate 
> the majority of the performance penalties? You dont need atomic 
> inc/dec if its thread local do you?

We in fact have documentation claiming 
std.typecons.SafeRefCounted is safe: "With -preview=dip1000, 
SafeRefCounted is safe if it's payload is accessed only with the 
borrow function." Walter must be referring to something different 
from that, or else the documentation must be wrong.