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{-# LANGUAGE ForeignFunctionInterface, MagicHash #-}
import GHC.ForeignPtr
import GHC.Ptr
import System.Mem
-- Don't use debugBelch() directly, because we cannot call varargs functions
-- using the FFI (doing so produces a segfault on 64-bit Linux, for example).
-- See Debug.Trace.traceIO, which also uses debugBelch2.
foreign import ccall "&debugBelch2" fun :: FunPtr (Ptr () -> Ptr () -> IO ())
new name = do
p <- newForeignPtr_ (Ptr name)
addForeignPtrFinalizerEnv fun (Ptr "finalizer 1 (%s)\n"#) p
addForeignPtrFinalizerEnv fun (Ptr "finalizer 2 (%s)\n"#) p
return p
main = do
p <- new "p"#
q <- new "q"#
r <- new "r"#
performGC -- collect p. finalizer order: 2, then 1.
-- print q
touchForeignPtr q
performGC -- collect q. finalizer order: 1, then 2.
-- expected order: 2, then 1.
-- print r
touchForeignPtr r
performGC -- collect r. finalizer order: 2, then 1.
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