DIP1000: Scoped Pointers (Discussion)

[Nick Treleaven via Digitalmars-d]

On Thursday, 11 August 2016 at 21:57:06 UTC, Walter Bright wrote:
> On 8/11/2016 6:36 AM, Marc Schütz wrote:
>> 4) The DIP doesn't address mutable aliasing at all. As a 
>> consequence, the
>> example `RefCountedSlice` is unsafe:
>>
>> auto arr = RefCountedSlice!int(10);
>> auto ptr = &arr[5];
>> arr = RefCountedSlice!int(42);
>> *ptr = 1;    // use after free
>
> The idea is to have containers return references by 'return 
> ref' or 'return scope' so the internal references can't escape 
> the expression they're used in.

So &arr[5] would be an error. The bug can still occur when 
passing arr and arr[5] both by reference to a function, but that 
case can (in future) be solved by making RefCountedSlice an @rc 
object*.

* https://wiki.dlang.org/DIP77