At least anymore. For C++ when the lexing nominally converted source
outside the basic character set to universal-character-name form, I think
it would be ambiguous in further lexing?

On Wed, May 11, 2022 at 4:49 PM Corentin <corentin.jabot_at_[hidden]> wrote:

> We should probably just get rid of the restriction that ucns cannot design
> basic character set member, it doesn't appear to be strongly motivated.
>
> On Wed, May 11, 2022, 22:25 Steve Downey via Liaison <
> liaison_at_[hidden]> wrote:
>
>> SG16, in reviewing the addition of the new characters to the basic
>> character set found a couple of awful ways it could result in conforming
>> code becoming non conforming.
>>
>> https://isocpp.org/files/papers/P2558R1.html
>>
>> #include <stdio.h> <https://isocpp.org/files/papers/P2558R1.html#cb2-2> <https://isocpp.org/files/papers/P2558R1.html#cb2-3>#define STR(x) #x <https://isocpp.org/files/papers/P2558R1.html#cb2-4> <https://isocpp.org/files/papers/P2558R1.html#cb2-5>int main() <https://isocpp.org/files/papers/P2558R1.html#cb2-6>{ <https://isocpp.org/files/papers/P2558R1.html#cb2-7> printf("%s", STR(\u0024)); // UCN for $ was allowed, now it is not <https://isocpp.org/files/papers/P2558R1.html#cb2-8>}
>> and
>>
>> #include <stdio.h> <https://isocpp.org/files/papers/P2558R1.html#cb3-2> <https://isocpp.org/files/papers/P2558R1.html#cb3-3>#define EAT(x) <https://isocpp.org/files/papers/P2558R1.html#cb3-4> <https://isocpp.org/files/papers/P2558R1.html#cb3-5>int main() <https://isocpp.org/files/papers/P2558R1.html#cb3-6>{ <https://isocpp.org/files/papers/P2558R1.html#cb3-7> EAT(\u0024) // UCN for $ was allowed, now it is not <https://isocpp.org/files/papers/P2558R1.html#cb3-8>}
>>
>> I am not sure this was noticed in reviewing N2701 but thought I'd bring
>> it to your attention.
>> SG16 had consensus to forward this to EWG.
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>>
>