Re: [Pharo-dev] Shouldn't new:0 fail for non-indexable classes

[Nicolai Hess]

2017-08-09 22:14 GMT+02:00 Eliot Miranda :

> Hi Nicolai,
>
> On Tue, Aug 8, 2017 at 12:10 PM, Nicolai Hess 
> wrote:
>
>> see fogbugz 20246 (https://pharo.fogbugz.com/f/c
>> ases/20246/Segfault-calling-new-0)
>>
>> Create a class with a single instance variable.
>>
>> call
>>
>> AClass new:0
>>
>> -> segfaults (on windows latest vm).
>> I can reproduce this on squeak (Squeak5.1-16549-32bit). It does not crash
>> right away, but
>> I was able to crash it by debugging into the new: call.
>>
>> from the comment of Behavior>>#new: , I would expect the error:
>>
>> self error: self printString, ' cannot have variable sized instances'
>>
>
> Quite right.  Squeak and Pharo used to have a funky class DirectoryEntry
> that was expected to be able to be instantiated with DirectoryEntry new:
> 0.  The (Spur) VM bug is that the object was being filled with 0's instead
> of nil.  I've fixed the Spur VM to now fail for any non-indexable class
> since, AFAICT, DirectoryEntry is no longer used in this way.
>

Thank you!


>
> _,,,^..^,,,_
> best, Eliot
>

Re: [Pharo-dev] Shouldn't new:0 fail for non-indexable classes

[Eliot Miranda]

Hi Nicolai,

On Tue, Aug 8, 2017 at 12:10 PM, Nicolai Hess  wrote:

> see fogbugz 20246 (https://pharo.fogbugz.com/f/
> cases/20246/Segfault-calling-new-0)
>
> Create a class with a single instance variable.
>
> call
>
> AClass new:0
>
> -> segfaults (on windows latest vm).
> I can reproduce this on squeak (Squeak5.1-16549-32bit). It does not crash
> right away, but
> I was able to crash it by debugging into the new: call.
>
> from the comment of Behavior>>#new: , I would expect the error:
>
> self error: self printString, ' cannot have variable sized instances'
>

Quite right.  Squeak and Pharo used to have a funky class DirectoryEntry
that was expected to be able to be instantiated with DirectoryEntry new:
0.  The (Spur) VM bug is that the object was being filled with 0's instead
of nil.  I've fixed the Spur VM to now fail for any non-indexable class
since, AFAICT, DirectoryEntry is no longer used in this way.

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

[Pharo-dev] Shouldn't new:0 fail for non-indexable classes

[Nicolai Hess]

see fogbugz 20246 (
https://pharo.fogbugz.com/f/cases/20246/Segfault-calling-new-0)

Create a class with a single instance variable.

call

AClass new:0

-> segfaults (on windows latest vm).
I can reproduce this on squeak (Squeak5.1-16549-32bit). It does not crash
right away, but
I was able to crash it by debugging into the new: call.

from the comment of Behavior>>#new: , I would expect the error:

self error: self printString, ' cannot have variable sized instances'