ANNOUNCE: GHC 6.10.2 Release Candidate 1

[Simon Marlow]

Bulat Ziganshin wrote:
> Hello Don,
> 
> Friday, March 20, 2009, 2:34:09 AM, you wrote:
> 
> the question is wider - how many other programs already used this
> behavior? it may be asked on main haskell list. what is the cost of
> reverting it back for 6.10.*? 

We could revert it, but lots of people asked for this feature 
(predictable finalizers), which is why we put it in 6.10.2.

The fix is fiarly easy: use Foreign.Concurrent.mkForeignPtr with a 
foreign import.

Cheers,
	Simon

> 
>> We must have the gtk2hs team invovled in this discussion. They were
>> using an undocumented feature. It may be trivial to fix.
> 
>> --Don
> 
>> jnf:
>>> Hello Simon,
>>> I've put a request about the issue on the gtk2hs users mailing list:
>>>
>>>> I've tried a gtk2hs app on ghc 6.10.2 release candidate.
>>>> It crashes frequently and Simon (as you can read down here) assumes it
>>>> is gtk2hs problem.
>>>> My question is:
>>>>        Is this problem known to gtk2hs developers?
>>>>        Is it really a gtk2hs problem?
>>>>        How difficult is it to fix the problem?
>>>>        When will we have a patch to use gtk2hs with 6.10.2, 
>>>>                is it already in the repo?      
>>> However, I'm a little surprised that a little version upgrade from 6.10.1 to
>>> 6.10.2 may break all gui apps based on gtk2hs. May it be that many more apps
>>> are affected because of this change? What's about wxhaskell e.g.? Well,
>>> maybe we have only few Haskell applications around, but usually I
>>> wouldn't expect such a dramatic effect from such a moderate upgrade. Is this
>>> fix so important to introduce it now? What does it help when it was never
>>> officially supported if it causes such troubles?
>>>
>>> Jürgen  
>>>  
>>>
>>>
>>> Simon Marlow-7 wrote:
>>>> jutaro wrote:
>>>>> I've installed a GUI application based on gtk2hs.
>>>>>         
>>>>> It frequently crashes with the error: 
>>>>> leksah: error: a C finalizer called back into Haskell.
>>>>> use Foreign.Concurrent.newForeignPtr for Haskell finalizers.
>>>>>
>>>>> This error did never occur with the 6.10 released version. It was
>>>>> verified
>>>>> that this happens on different machines. I've no idea how to isolate this
>>>>> bug.
>>>> This will need to be fixed in gtk2hs.  Previously GHC allowed finalizers
>>>> to 
>>>> call back into Haskell, but this was never officially supported.  Now it
>>>> is 
>>>> officially unsupported, because finalizers created via
>>>> Foreign.mkForeignPtr 
>>>> are run directly by the garbage collector.
>>>>
>>>> See
>>>>
>>>>   http://hackage.haskell.org/trac/ghc/ticket/1364
>>>>
>>>> Cheers,
>>>>     Simon
>>>> _______________________________________________
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>>>> Glasgow-haskell-users at haskell.org
>>>> http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
>>>>
>>>>
>>> -- 
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>>>
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> 
> 
>