CVS HEAD ghc fails with "Panic!"

Hi, the GHC version from the current CVS HEAD aborts with an internal error when doing this: $ darcs get http://cryp.to/hsemail $ cd hsemail $ ghc -O2 --make -o message-test message-test.hs | Chasing modules from: message-test.hs | Compiling Rfc2234 ( ./Rfc2234.hs, ./Rfc2234.o ) | ghc-6.3: panic! (the `impossible' happened, GHC version 6.3): | app_match: unbound tpl c{tv a1a9} Compiling with -O instead of -O2 works, though. Peter