Re: [squeak-dev] BlockClosure asContext losing bound variable?

> Hi Rob, Hi All,
>
> On Sun, Jun 27, 2010 at 3:34 PM, Rob Withers <[hidden email]> wrote:
>
>> I am getting a walkback on this code, with a valid vat:
>>
>> EventualProcess class>>#newOnVat: vat
>>        ^ super new
>>                suspendedContext: [
>>                        vat processSends.
>>                        Processor terminateActive] asContext;
>>                 priority: Processor userSchedulingPriority;
>>                 eventualName: 'vat thread';
>>                 vat: vat;
>>                 yourself
>>
>> once it has been resumed.  The exception is
>> UndefinedObject(Object)>>doesNotUnderstand: #processSends.  Somehow the vat
>> variable inside the Closure/MethodContext has become nil.    Anyone know
>> about this stuff?
>>
>
>
> This is due to a bad bug i the closure support for BlockClosure>>asContext,
> which was forgetting to push any copied values (in the above case the
> argument vat) onto the stack of the new context so that when the process
> resumed the initial pushTemp0 that should push the copied value of vat in
> fact pushed (at least in the Cog VM) 4 bytes from the middle of the method,
> and hence bang!
>
> The fixes are in Kernel-eem.468 and Kernel-eem.469.  Its probably best to
> load Kernel-eem.468 and then Kernel-eem.469 rather than just Kernel-eem.469
> because the system will crash if the fixes come i in the wrong order.
> Kernel-eem.468

> also fixes restart in blocks in the debugger (its the same issue; forgetting
> to initialize the context with any arguments and copied values; local temps
> get initialized by explicit pushNil bytecodes).
>
> thanks for the test case Rob!
>
> best
> Eliot
>
> P.S. Here are the methods:
>
>
>> Many thanks,
>> Rob
>>
>>
>