DIP 1021--Argument Ownership and Function Calls--Final Review

[Olivier FAURE]

On Wednesday, 18 September 2019 at 11:18:30 UTC, Walter Bright 
wrote:
> The smaller picture is that one cannot create a ref counted 
> objected that can safely expose a ref to its payload without 
> this proposal.

One cannot create a ref-counted object that can safely expose its 
payload *with* this proposal either.

eg:

     @safe:

     void foo(ref RefCounted rc, ref RefCounted rc2) {
         rc.reset();
         rc2.get() = 42;		// Whoops, memory corruption
     }

     void test() {
         RefCounted rc = someData();
         RefCounted* rc2 = &rc;

         foo( rc, *rc2 );
     }

Any proposal which doesn't have data flow analysis won't provide 
actual memory safety.