ghc 6.2 possible bug with gcc 3.3.x, strange parse error

[Alastair Reid]

> I can't see a workaround, so it might be that string gaps will not be
> useable with CPP from now on.

Maybe there is a small, simple K&R-era cpp implementation we could use instead 
of relying on the gcc one.  Anyone know of one?  Features used are probably:

#define
__LINE__
#undef
#ifdef
#if defined X
some string splicing using ## and friends
and arbitrary constant expressions

--
Alastair Reid