On 17/04/2021 09.04, Jens Gustedt via Liaison wrote:
> on Fri, 16 Apr 2021 17:11:12 -0400 you (Steve Downey
> <sdowney_at_[hidden]>) wrote:

>> There were some grammar changes just to fix some problems with
>> pp-tokens, making sure that UCNs always were, and dealing with
>> pp-numbers that don't turn out to be numbers.
>
> That worries me a bit more. I would be good if that would converge to
> a common treatement in C and C++. I don't think that pp-numbers in C
> ever caused serious problems. They just survive for later translation
> phases and if they are not appropriate, the problem is handled there.

The paper is here:

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p1949r6.html

The pp-number change in particular is just applying the new UAX#31-based
lexing grammar non-terminals to these. Nothing to see, I believe.

Note that the lexing grammar presented here will need to change again
once C++ switches to a "model C" approach (no early transformation
of extended characters into UCNs)
http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2021/p2314r1.html

Jens