Valgrind support
This is based on code in gtk2hs.
$ valgrind -q ./finalizer_queue
finalizer_queue: internal error: stg_ap_v_ret
(GHC version 6.10.3 for i386_unknown_linux)
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Killed
Unfortunately this test doesn't crash without Valgrind.
My guess is that this bit is the problem:
finalizer <- fixIO $ \dPtr -> mkThunk $ do
freeHaskellFunPtr callback
freeHaskellFunPtr dPtr
Perhaps the documentation should say not to do this?