CPP warning

[Neil Booth]

Mark Mitchell wrote:-

> So would it make sense to put it under ENABLE_CHECKING and/or make it
> an `abort'?

Yes, let's do that.  I put it in because some of the issues there are
difficult to get right, and anyone, including myself, changing it in
future could easily get it wrong.

I'll post a patch soon to put it under ENABLE_CHECKING; I don't think
an abort would be good since that would completely prevent you from
compiling old preprocessed source.

Neil.