hpc and CPP don't mix on Windows

Originaly reported by Dominic Steinitz here: http://www.haskell.org/pipermail/glasgow-haskell-users/2009-July/017511.html

On Windows, with these files:

CommonHPC.hs:

module Main (main) where

import Common

main = do
  test
  test

test = do
  putStrLn $ show $ fact 4
  putStrLn $ show $ fact 5

Common.hs:

module Common (fact) where

fact 0 = 1
fact n = n * fact (n-1)

This works:

$ ghc -fhpc --make CommonHPC
$ ./CommonHPC
$ cat CommonHPC.exe.tix
Tix [ TixModule "Main" 693125724 18 [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], TixModule "Common" 4136915291 8 [2,9,9,9,9,9,9,11]]

but with -cpp we get no ticks for Common:

$ ghc -fhpc --make CommonHPC -cpp
$ ./CommonHPC
$ cat CommonHPC.exe.tix
Tix [ TixModule "Main" 693125724 18 [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], TixModule "Common" 3370079577 0 []]

Trac metadata

Trac field	Value
Version	6.10.4
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Code Coverage
Test case
Differential revisions
BlockedBy
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Blocking
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Operating system
Architecture