Wow, that is one nasty bug.  Amazing catch you guys.

On Tue, Feb 23, 2016 at 6:04 PM, Eliot Miranda <eliot.miranda at gmail.com> wrote:
> 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
>
>
>