internal error: stg_ap_pp_ret (with terminfo)

When trying to run the haskeline package against HEAD, I sometimes get bus errors, segfaults or the following error:

Test: internal error: stg_ap_pp_ret
    (GHC version 6.9.20080827 for i386_apple_darwin)
    Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
Abort trap

I've tried to strip down the relevant parts of the code. Attached is my best attempt to isolate the error. The code runs fine on 6.8.3, but crashes with a segfault or bus error if it was compiled with ghc-6.9.20080827:

$ ~/tmp/ghc-stage/bin/ghc --make -threaded Test.hs -fforce-recomp -lncurses
[1 of 1] Compiling Main             ( Test.hs, Test.o )
Linking Test ...
$ ./Test 
foobar1
Starting loop...
About to do the bad thing.
Segmentation fault

This is with OS X 10.5.4.

Trac metadata

Trac field	Value
Version	6.9
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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