Can you tell which process is crashing? Is it the GHC process that is interpreting Setup.hs, or the process invoked by Setup.hs to build the package?

I suspect it is the GHC process that is invoked by Setup.hs, but I do not have any hard evidence to support this.

One thing you could try is compiling Setup.hs to a binary, and running that instead.

That worked! I think this counts as evidence for the above.

Also, if you could run Setup like this and send us the output:

$ ./setup build -v

(or the runhaskell version, if that's the only one that crashes)

I did it via runhaskell: runhaskell Setup.hs build -v Preprocessing library Vasicek-0.3... Building Vasicek-0.3... This is all what it said before the crash... Just about 15 minutes ago I fixed the problem (at least I hope I did) by installing the snapshot of GHC 6.4.2 of February 27 (BTW, the cc1.exe is missing from the tar file). I also found at least one difference between the PC where the problem showed up and the one where it did not. Both PCs had Cygwin installed. On the PC where the problem did not show up, the Cygwin executables shadowed the Windows programs with the same name: e.g. if I type 'find' in Windows command prompt, I get the UNIX find. On the PC where the problem did show up, it was the other way: I get the Windows find (of course, from the bash shell I always get the UNIX find). I do not know, though, if this is linked in any way to the GHC problem. I spent some time playing with PATH to try to make the two PCs behave the same, but I could not (I do not have Admin priviledges). The GHC was always started from the Windows prompt, never from bash. Anyway, as the problem is solved by moving from 6.4.1 to 6.4.2, we can conclude that it was caused by one of the bugs fixed after 6.4.1, and close the issue for now. If you, however, would like to continue investigation, please let me know -- I can easily reproduce the problem, and I'll be happy to get any extra information for you (once I know how to get it). I will keep version 6.4.1 for the time being. Thank you very much for the help. Cheers, Cyril