Why is 'scope' so weak?

[Andrei Alexandrescu]

On 11/24/10 5:06 AM, Lars T. Kyllingstad wrote:
> On Tue, 23 Nov 2010 23:26:54 -0500, Robert Jacques wrote:
>
>> On Tue, 23 Nov 2010 07:59:27 -0500, Lars T. Kyllingstad
>> <public at kyllingen.nospamnet>  wrote:
>>
>>> If I've understood things correctly, by marking a delegate parameter
>>> with 'scope' you tell the compiler not to create a true closure for the
>>> delegate.  Effectively you're saying "I promise not to escape this
>>> delegate, so you don't need to copy its context to the heap".
>>>
>>> In brief, my question is:  Why doesn't the compiler enforce this
>>> promise?  In particular, why is 'scope' not a type constructor?
>>
>> For scope to be a type constructor, D requires some form of
>> ownership-types&  local escape analysis. Just like mutable and immutable
>> data needs const, I think stack/thread-local/shared data needs scope.
>> (There is an old proposal on the wiki about the technical
>> implementation, though it's badly worded) But my understanding is that
>> all things ownership related are relegated to D3.
>
> Well, I think something needs to be done about it in D2 as well, because
> right now 'scope' allows memory corruption to happen even in safe mode,
> as demonstrated by this slightly modified example:
[snip]

This is a bug. Could you please file it as major?

Andrei