I am using GHC 6.12.1, in Ubuntu 10.04

When I try to use the FFI syntax for static storage, only modules running in interpreted mode (ie GHCI) work properly. Compiled modules have invalid pointers, and do not work. I'd like to know whether anybody can reproduce the problem, whether this an error in my code or GHC, and (if the latter) whether it's a known issue.

Given the following three modules:

-- A.hs
{-# LANGUAGE ForeignFunctionInterface #-}
module A where
import Foreign
import Foreign.C

foreign import ccall "&sys_siglist"
    siglist_a :: Ptr CString

--

-- B.hs
{-# LANGUAGE ForeignFunctionInterface #-}
module B where
import Foreign
import Foreign.C

foreign import ccall "&sys_siglist"
    siglist_b :: Ptr CString

--

-- Main.hs
{-# LANGUAGE ForeignFunctionInterface #-}
module Main where
import Foreign
import Foreign.C
import A
import B

foreign import ccall "&sys_siglist"
    siglist_main :: Ptr CString

main = do
    putStrLn $ "siglist_a    = " ++ show siglist_a
    putStrLn $ "siglist_b    = " ++ show siglist_b
    putStrLn $ "siglist_main = " ++ show siglist_main

    peekSiglist "a   " siglist_a
    peekSiglist "b   " siglist_b
    peekSiglist "main" siglist_main

peekSiglist name siglist = do
    ptr <- peekElemOff siglist 2
    str <- maybePeek peekCString ptr
    putStrLn $ "siglist_" ++ name ++ "[2] = " ++ show str

I would expect something like this output, where all pointer values identical and valid:

$ runhaskell Main.hs 
siglist_a    = 0x00007f53a948fe00
siglist_b    = 0x00007f53a948fe00
siglist_main = 0x00007f53a948fe00
siglist_a   [2] = Just "Interrupt"
siglist_b   [2] = Just "Interrupt"
siglist_main[2] = Just "Interrupt"

However, if I compile A.hs (with ghc -c A.hs), then the output changes to:

$ runhaskell Main.hs 
siglist_a    = 0x0000000040378918
siglist_b    = 0x00007fe7c029ce00
siglist_main = 0x00007fe7c029ce00
siglist_a   [2] = Nothing
siglist_b   [2] = Just "Interrupt"
siglist_main[2] = Just "Interrupt"