c2hs: fails reading its own intermediate representation (.chi)

[guest]

This bug was reported against the Debian package of c2hs, at  http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=652507

c2hs uses shown Language.C data structures as an intermediate representation (the .chi files), and has its own code for parsing them. It seems that Language.C has changed its Show instance for lexemes, and c2hs can no longer parse its own .chi files.

The symptom for me is that "cabal build" fails with the following error message:

c2hs: Prelude.read: no parse

Patch attached.

(Patch at  http://bugs.debian.org/cgi-bin/bugreport.cgi?msg=5;filename=c2hs.diff;att=1;bug=652507)

Greetings, Joachim