ANNOUNCE: GHC 6.10.2 Release Candidate 1

Simon Marlow marlowsd at
Thu Mar 19 06:51:23 EDT 2009

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.



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