Hi Levente,

On Tue, Feb 23, 2016 at 3:09 PM, Levente Uzonyi <leves at caesar.elte.hu>
wrote:

> I found that
> - it requires the use of primitive 83 with 3 arguments (aka
> #perform:with:with:. 2 and 4 argument variants don't trigger the bug)
> - its result must be passed immediately as an argument to another method
> (using a temporary to store the intermediate value won't trigger the error)
> - all this has to be evaluated in a block at least twice (the first
> evaluation won't trigger the bug).
>
> Here's a smaller example:
>
> [ '' copyReplaceFrom: 1 to: 0 with: ('' perform: #copyFrom:to: with: 1
> with: 0) ] value; value
>
> I decided to use #copyReplaceFrom:to:with: instead of #,, because the
> former will raise a debugger due to the invalid arguments.
>
> Here's a different one:
>
> [ self haltIf: ({ true } perform: #at:put: with: 1 with: false) ] value;
> value
>
> This clearly shows, that first argument of #perform:with:with: stays on
> the stack somehow.
>
> Going through the code in the debugger doesn't trigger the bug, which
> makes me think that the jitted version of #perform:with:with: doesn't pop
> its first argument from the stack.


 Bingo!  Thanks.  In fact the primitive fails to pop all but the last
argument.  I'll have a fix ready soon.

Levente
>
>
> On Tue, 23 Feb 2016, Stéphane Rollandin wrote:
>
> I have a nice one:
>>
>> In (seemingly) any 5.0 image, with the latest Spur, type the following in
>> a workspace and printIt a couple of time:
>>
>>
>> (1 to: 3) collect: [:i |
>>         m := ''.
>>         2 timesRepeat: [m := m,  ('1234' perform: #copyFrom:to: with: 2
>> with: 4)].
>>         m]
>>
>>
>> I get kind of randomly either #('234' '' '') or the correct #('234234'
>> '234234' '234234'), or at times #('234234' '' '').
>>
>>
>> Attached is the same code, this time in a method. It is even funkier,
>> since a common answer is then 'copyFrom:to:234', although I sometimes get
>> '234234' ...
>>
>>
>>
>> Stef
>>
>>
>
>
>


-- 
_,,,^..^,,,_
best, Eliot
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