Allocator-aware @safe reference counting is still not possible

[Atila Neves]

On Saturday, 28 January 2023 at 15:56:54 UTC, Nick Treleaven 
wrote:
> On Sunday, 22 January 2023 at 15:28:53 UTC, Atila Neves wrote:
>> [...]
>
> `isolated` would be nice, but for now we can model it with a 
> struct so that this works:
> ```d
> class Mallocator : IAllocator
> {
>     import core.stdc.stdlib : free, malloc;
>
>     void* safeAllocate(size_t n) @trusted
>     {
>         return malloc(n);
>     }
>
>     void safeDeallocate(Isolated!(void*) ip) @trusted
>     {
>         ip.unwrap.free;
>     }
> }
>
> void main()
> {
>     IAllocator a = new Mallocator;
>     scope m = a.safeAllocate(4);
>     auto ip = (() @trusted => 
> assumeIsolated(a.safeAllocate(4)))();
>     a.safeDeallocate(ip.move);
>     assert(ip.unwrap == null);
> }
> ```
> Working code:
> https://github.com/ntrel/stuff/blob/master/typecons/isolated.d
>
> Isolated could go in std.typecons.

I don't understand how this presents a @safe interface.