>> One consistent view might be to allow everything as preprocessing tokens in phase 4
> (maybe concatenation and stringization will make those vanish before phase 7),
> and then do all the checking when transitioning to phase 7.

I’d suggest the place to check for an illegal token is the new phase 6, that just does pp-token to token conversion.

AlisdairM
อลิสแดร์ม
Sent from my iPhone