Very limited shared promotion

[Walter Bright]

On 6/21/2019 5:26 PM, Manu wrote:
> I've asked you 5 or 6 times to show how to pass a pointer to another thread 
> without violating scope.
> Can you show it? You keep saying you can.

     void foo(scope shared(int)* p) @trusted {
         auto t = startThread();
         passToThread(t, p);
         waitForThreadToExit(t);
     }


> You need an acquire fence before the function returns, it's trivial.

That's right it is. But the compiler doesn't know you put one there, and scope 
does not cause it to be put there, and @safe does not, either.


> If you want @safe expansion, that's future work, and I personally couldn't care 
> less about that work. I can create safe libraries with @trusted functions, and I 
> could do it _right now_.

You're assuming semantics for scope and @safe that are not there, and so the 
compiler cannot assume them, either.