docon 2.06 triggers compiler bug

I have been trying to compile the docon package, which is
available from <http://www.haskell.org/docon/>, but despite
serious efforts, I failed. It appears that ghc goes into an
infinite loop when compiling the module pol/factor/Pfact__.hs.
The compiler doesn't issue any warnings or errors, but I just
won't return.

When compiling the source code with ghc 6.0, everything works
fine though, so I guess, this really is a bug in the current
HEAD version.

To re-produce this error (on Unix), do as follows:

    wget http://haskell.org/docon/distrib/2.06/docon-2.06.zip
    mkdir docon-test && cd docon-test
    unzip -a ../docon-2.06.zip
    cd docon/source/
    mkdir export
    make ghc=ghc-6.3 s=`pwd` obj

Peter