It looks like Eliot removed the check in 2011. Before that it read:

canCascade
	^(receiver == NodeSuper or: [special > 0]) not

- Bert -

> On 19.02.2015, at 17:35, J. Vuletich (mail lists) <juanlists at jvuletich.org> wrote:
> 
> Hi Levente,
> 
> Thanks for raising this. I don't know how to fix it, but in Cuis, I've just disabled these selectors in #canCascade (#ifNil: too, even if not really needed). I recompiled the system afterwards without error notifications. And I see no real value in this coding style, so I see no downside in just disallowing it.
> 
> Cheers,
> Juan Vuletich
> 
> Quoting Levente Uzonyi <leves at elte.hu>:
> 
>> Hi All,
>> 
>> There's a bug in the compiler which should be easy to fix for someone familiar with the code.
>> The following expression returns #(nil nil true true) instead of #(nil nil nil nil):
>> 
>> {
>> nil
>> 	ifNil: [ 1 ] ifNotNil: [ 2 ];
>> 	yourself.
>> nil
>> 	ifNil: [ 1 ];
>> 	yourself.
>> nil
>> 	ifNotNil: [ 2 ];
>> 	yourself.
>> nil
>> 	ifNotNil: [ 2 ] ifNil: [ 1 ];
>> 	yourself.
>> }
>> 
>> The cause of the problem is that in case of #ifNotNil: and #ifNotNil:ifNil: the deoptimization doesn't clear all previously generated optimized bytecodes.
>> E.g. in case of #ifNotNil: instead of
>> 
>> <73> pushConstant: nil
>> <88> dup
>> <8F 00 00 02> closureNumCopied: 0 numArgs: 0 bytes 33 to 34
>>    <76> pushConstant: 1
>>    <7D> blockReturn
>> <E0> send: ifNotNil:
>> <87> pop
>> <D1> send: yourself
>> 
>> we get
>> 
>> <73> pushConstant: nil
>> <73> pushConstant: nil
>> <C6> send: ==
>> <88> dup
>> <8F 00 00 02> closureNumCopied: 0 numArgs: 0 bytes 33 to 34
>>    <76> pushConstant: 1
>>    <7D> blockReturn
>> <E0> send: ifNotNil:
>> <87> pop
>> <D1> send: yourself
>> 
>> It would be great to write some tests which cover all such cases (including other methods), but I'm not sure what form is the best for this. Simple tests which just verify some values? Or something that checks the generated bytecodes?
>> 
>> Levente



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