Re: Unicode in C Sources

From	James Kuyper <jameskuyper@alumni.caltech.edu>
Newsgroups	comp.lang.c
Subject	Re: Unicode in C Sources
Date	2020-02-02 16:58 -0500
Organization	A noiseless patient Spider
Message-ID	<r17gn4$447$1@dont-email.me> (permalink)
References	(4 earlier) <r150nk$nsg$1@gioia.aioe.org> <1XzZF.178637$hD4.62031@fx47.iad> <r16v5c$1bff$1@gioia.aioe.org> <r178r3$eqm$1@dont-email.me> <r17clc$1boh$1@gioia.aioe.org>

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On 2/2/20 3:49 PM, Manfred wrote:
> On 2/2/2020 8:44 PM, James Kuyper wrote:
>> On 2/2/20 11:59 AM, Manfred wrote:
>>> On 2/2/2020 2:14 PM, Richard Damon wrote:
>> ...
>>>> If written in the (ugly) \u notation then it is supposed to accept them,
>>>> but as the actual Unicode character itself, it is a function of what the
>>>> implementation defines as it extended source character set.
>>>>
>>>> My understanding is that the \u notation is designed that for a compiler
>>>> that does NOT accept full unicode source, you could have a pre-filter
>>>> phase that processes the source and converts the Unicode characters into
>>>> Universal characters (the \u and \U notation). It is even written so
>>>> this could be part of the early phases of the compiler.
>>>
>>> In fact the wording used in C++ standard is more explicit on this
>>> (translation phase 1), although my understanding of the wording of C
>>> standard mandates that the characters in D.1 be accepted in identifiers
>>> as well (with the exception of D.2 as initial)
>>
>> C++ does not allow an implementation-defined set of extended characters
>> to appear in an identifier, and it does not allow UCNs at the start of
>> an identifier.
> Almost correct: C++ allows UCNs at the start of an identifier, except 
> those in table 3 [lex.name] (which is the counterpart of D.2)
> 
>   C allows both.

I'd forgotten (if in fact, I ever knew) that C imposes the same
restrictions on initial UCNs. I should have reviewed the wording more
carefully before posting that comment. The part about an
"implementation-defined set of extended characters" is correct, and was
my main point.

>> In C, The UCNs listed in D.1 must be accepted. Whether or not the
>> corresponding extended characters (if any) are accepted is entirely
>> implementation-defined.
>>
> This is the part that is not explicit (to me) in the C standard, when I 
> read translation phase 1.

The only thing that the description of translation phase 1 says which is
relevant is "Physical source file multibyte characters are mapped, in an
implementation-defined manner, to the source character set." Keeping
mind that the extended source character set is a subset of the extended
source character set, this implies that extended characters are
permitted in C programs, but doesn't say anything to address the issue
of where they are permitted.

The relevant issue is the syntax of identifiers. The relevant wording is
in 6.4.2.1, which identifies "universal-character-name" and "other
implementation-defined characters" as two of the permitted forms that an
"identifier-nondigit" can take. 6.4.2.1p3 says "An implementation may
allow multibyte characters that are not part of the basic source
character set to appear in identifiers; which characters and their
correspondence to universal character names is implementation-defined."

Thread

Unicode in C Sources F Russell <fr@random.info> - 2020-02-01 17:12 +0000
  Re: Unicode in C Sources Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-01 17:37 +0000
    Re: Unicode in C Sources Anton Shepelev <anton.txt@gmail.com> - 2020-02-01 20:43 +0300
      Re: Unicode in C Sources Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-02-01 10:57 -0800
        Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-02 16:58 +0100
          Re: Unicode in C Sources F Russell <fr@random.info> - 2020-02-02 17:05 +0000
            Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-02 19:52 +0100
              Re: Unicode in C Sources Bart <bc@freeuk.com> - 2020-02-02 19:20 +0000
            Re: Unicode in C Sources Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-03 12:38 +0000
              Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-03 09:16 -0500
                Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-03 15:32 +0100
                Re: Unicode in C Sources Öö Tiib <ootiib@hot.ee> - 2020-02-03 09:01 -0800
                Re: Unicode in C Sources Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-03 21:15 +0000
              Re: Unicode in C Sources F Russell <fr@random.info> - 2020-02-04 02:06 +0000
              Re: Unicode in C Sources F Russell <fr@random.info> - 2020-02-04 02:19 +0000
                Re: Unicode in C Sources Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-04 02:50 +0000
                Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-04 08:16 +0100
    Re: Unicode in C Sources Bart <bc@freeuk.com> - 2020-02-01 18:10 +0000
      Re: Unicode in C Sources Richard Damon <Richard@Damon-Family.org> - 2020-02-01 15:19 -0500
        Re: Unicode in C Sources Manfred <invalid@add.invalid> - 2020-02-02 00:13 +0100
          Re: Unicode in C Sources Manfred <invalid@add.invalid> - 2020-02-02 00:46 +0100
            Re: Unicode in C Sources Bart <bc@freeuk.com> - 2020-02-02 00:24 +0000
          Re: Unicode in C Sources Richard Damon <Richard@Damon-Family.org> - 2020-02-02 08:14 -0500
            Re: Unicode in C Sources Manfred <noname@add.invalid> - 2020-02-02 17:59 +0100
              Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-02 14:44 -0500
                Re: Unicode in C Sources Manfred <noname@add.invalid> - 2020-02-02 21:49 +0100
                Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-02 16:58 -0500
                Re: Unicode in C Sources Manfred <noname@add.invalid> - 2020-02-03 15:33 +0100
                Re: Unicode in C Sources Manfred <noname@add.invalid> - 2020-02-03 15:38 +0100
                Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-03 10:25 -0500
                Re: Unicode in C Sources Manfred <noname@add.invalid> - 2020-02-03 19:11 +0100
                Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-03 15:59 -0500
                Re: Unicode in C Sources Manfred <noname@add.invalid> - 2020-02-04 16:51 +0100
                Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-04 16:05 -0500
                Re: Unicode in C Sources Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-19 12:17 -0800
      Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-02 17:09 +0100
        Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-02 14:46 -0500
          Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-02 21:39 +0100
            Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-02 17:07 -0500
              Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-03 13:12 +0100
                Re: Unicode in C Sources jacobnavia <jacob@jacob.remcomp.fr> - 2020-02-03 16:46 +0100
                Re: Unicode in C Sources Bart <bc@freeuk.com> - 2020-02-03 16:47 +0000
                Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-03 13:36 -0800
                Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-03 23:56 +0100
                Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-03 13:06 -0500
                Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-03 22:25 +0100
                Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-03 13:29 -0800
                Re: Unicode in C Sources Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-19 12:30 -0800
                Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-19 14:19 -0800
                Re: Unicode in C Sources Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-02 07:50 -0700
                Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-02 08:16 -0700
                Re: Unicode in C Sources Bart <bc@freeuk.com> - 2020-02-03 22:33 +0000
                Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-03 23:05 -0500
                Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-03 23:10 -0500
                Re: Unicode in C Sources Manfred <noname@add.invalid> - 2020-02-04 18:05 +0100
                Re: Unicode in C Sources already5chosen@yahoo.com - 2020-02-04 09:38 -0800
                Re: Unicode in C Sources Manfred <noname@add.invalid> - 2020-02-04 18:46 +0100
                Re: Unicode in C Sources James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-04 16:07 -0500
            Re: Unicode in C Sources Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-02-02 14:54 -0800
      Re: Unicode in C Sources Siri Cruise <chine.bleu@yahoo.com> - 2020-02-03 15:10 -0800
  Re: Unicode in C Sources jacobnavia <jacob@jacob.remcomp.fr> - 2020-02-03 07:47 +0100
    Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-03 14:00 +0100
      Re: Unicode in C Sources jacobnavia <jacob@jacob.remcomp.fr> - 2020-02-03 16:45 +0100
        Re: Unicode in C Sources Guillaume <message@bottle.org> - 2020-02-03 17:54 +0100
        Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-03 22:36 +0100
          Re: Unicode in C Sources jacobnavia <jacob@jacob.remcomp.fr> - 2020-02-04 16:33 +0100
            Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-04 16:45 +0100
              Re: Unicode in C Sources Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-02-04 13:02 -0800
                Re: Unicode in C Sources jacobnavia <jacob@jacob.remcomp.fr> - 2020-02-04 23:18 +0100
                Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-05 11:07 +0100
                Re: Unicode in C Sources Manfred <noname@add.invalid> - 2020-02-05 14:49 +0100
                Re: Unicode in C Sources Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-16 06:23 -0800
                Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-05 10:54 +0100
              Re: Unicode in C Sources Manfred <noname@add.invalid> - 2020-02-05 14:51 +0100
                Re: Unicode in C Sources Bart <bc@freeuk.com> - 2020-02-05 14:03 +0000
                Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-05 16:31 +0100
                Re: Unicode in C Sources Bart <bc@freeuk.com> - 2020-02-05 15:59 +0000
                Re: Unicode in C Sources scott@slp53.sl.home (Scott Lurndal) - 2020-02-05 16:02 +0000
                Re: Unicode in C Sources Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-05 16:59 +0000
                Re: Unicode in C Sources Bart <bc@freeuk.com> - 2020-02-05 18:02 +0000
                Re: Unicode in C Sources jacobnavia <jacob@jacob.remcomp.fr> - 2020-02-05 19:37 +0100
                Re: Unicode in C Sources Manfred <noname@add.invalid> - 2020-02-05 19:37 +0100
                Re: Unicode in C Sources jacobnavia <jacob@jacob.remcomp.fr> - 2020-02-05 21:02 +0100
                Re: Unicode in C Sources Ian Collins <ian-news@hotmail.com> - 2020-02-06 10:34 +1300
                Re: Unicode in C Sources Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-05 23:10 +0000
                Re: Unicode in C Sources Manfred <noname@add.invalid> - 2020-02-06 13:53 +0100
                Re: Unicode in C Sources Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-06 13:26 +0000
                Re: Unicode in C Sources Richard Damon <Richard@Damon-Family.org> - 2020-02-06 07:27 -0500
                Re: Unicode in C Sources Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-05 23:03 +0000
                Re: Unicode in C Sources Mikko Rauhala <mjr@iki.fi> - 2020-02-06 10:46 +0000
                Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-05 21:47 +0100
                Re: Unicode in C Sources Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-05 22:50 +0000
                Re: Unicode in C Sources scott@slp53.sl.home (Scott Lurndal) - 2020-02-07 00:25 +0000
                Re: Unicode in C Sources Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-07 02:07 +0000
                Re: Unicode in C Sources David Brown <david.brown@hesbynett.no> - 2020-02-05 16:26 +0100
      Re: Unicode in C Sources antispam@math.uni.wroc.pl - 2020-04-18 03:58 +0000

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