This bug is not very important, it doesn't cause any problems with the boost preprocessor library. It's just something I stumbled across that could potentially cause problems.

     #define FOO(x) x

     FOO(1)1

This expands to '11' when it should expand to '1 1'.

I believe that internally the two 1's should be stored as separate but adjacent tokens, then, if converted to text, the whitespace should be inserted to show that they are separate. But I'm not an expert on this, and I don't have a copy of the standard to check, so there's a good chance that I could be wrong.

As before, I've attached some relevant tests from wave.

Daniel