cpphs bug

Hi Malcolm, This appears to be a cpphs bug. For the following code #define x (1 == 1) #if x YES #else NO #endif cpphs 1.18.1 prints NO, while the expected output (and the output GNU cpp produces) is YES. If parentheses around 1 == 1 are removed, or if x is inlined manually, then cpphs correctly prints YES. This affects GHC 7.8 users in a serious way: GHC 7.8 uses cpphs, and the above code is a simplified version of macros generated by cabal. For this reason, for instance, type-eq 0.4.1 cannot be build by GHC 7.8 RC1, despite the proper CPP guards. Roman