Error: symbol `ghczmprim_GHCziUnit_Z0T_closure' is already defined

This module:

module Foo where

f :: Int -> Int
f _ | () `seq` False = undefined
    | otherwise = error "XXX"

g :: Int -> Int
g _ | () `seq` False = undefined
    | otherwise = error "XXX"

doesn't compile with 6.8.3 or the HEAD; here's what happens with the HEAD (compiled with -DDEBUG, but I'm pretty sure it wouldn't work anyway):

$ ghc -fforce-recomp -c Foo.hs
ghc-6.9.20080701: panic! (the 'impossible' happened)
  (GHC version 6.9.20080701 for x86_64-unknown-linux):
        ASSERT failed! file stgSyn/CoreToStg.lhs line 922 (){v 71} [lid]

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

$ ghc -fforce-recomp -c Foo.hs -O
/tmp/ghc4665_0/ghc4665_0.s: Assembler messages:

/tmp/ghc4665_0/ghc4665_0.s:95:0:
     Error: symbol `ghczmprim_GHCziUnit_Z0T_closure' is already defined

The original problem report, using Takusen, is here: http://www.haskell.org/pipermail/glasgow-haskell-users/2008-June/015037.html

Trac metadata

Trac field	Value
Version	6.9
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	Unknown
Architecture	Unknown