[Bug c/107954] Support -std=c23/gnu23 as aliases of -std=c2x/gnu2x

["joseph at codesourcery dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107954

--- Comment #3 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
Editorial review before the CD ballot slipped the schedule.  Second-round 
editorial review after a huge number of changes in the editorial review 
slipped the schedule.  Getting a final draft with all the changes into the 
CD ballot process slipped the schedule.  The January meeting is two weeks 
later than originally planned because of the schedule delays.  I just sent 
206 comments on the CD to BSI for submission to ISO as the UK comments and 
if other NBs have similar numbers of comments, (a) it wouldn't surprise me 
if there's difficulty in getting through all of them in a single week's 
meeting (even if we find a way not to need to discuss all the editorial 
comments individually in the meeting) and (b) there could easily be 
further delays getting all the changes into the working draft and reviewed 
for being correctly applied.  So despite the 56-day "ISO editing" period 
on the schedule before the DIS ballot (which may be meant to deal with all 
the editorial issues ISO comes up with at the last minute), it's entirely 
plausible there could be schedule slip for the DIS ballot - even supposing 
we don't need any extra ballot stages (CD2 or FDIS).

So while it's possible that the new standard will be published in 2023 - 
or with a __STDC_VERSION__ value from 2023 even if published in 2024 - 
there is plenty of scope for the schedule to slip given the amount of work 
that still needs to be done on the draft.