Re: Unicode in C Sources

From	Manfred <noname@add.invalid>
Newsgroups	comp.lang.c
Subject	Re: Unicode in C Sources
Date	2020-02-03 19:11 +0100
Organization	Aioe.org NNTP Server
Message-ID	<r19nnk$86a$1@gioia.aioe.org> (permalink)
References	(7 earlier) <r178r3$eqm$1@dont-email.me> <r17clc$1boh$1@gioia.aioe.org> <r17gn4$447$1@dont-email.me> <r19avh$7l4$1@gioia.aioe.org> <r19e0i$5nv$1@dont-email.me>

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On 2/3/2020 4:25 PM, James Kuyper wrote:
> On 2/3/20 9:33 AM, Manfred wrote:
>> On 2/2/2020 10:58 PM, James Kuyper wrote:
>>> 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:
> ...
>>> 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."
>>
>> And that's different from the C++ standard which adds: "Any source file
>> character not in the basic source character set (5.3) is replaced by the
>> universal-character-name that designates that character".
> 
> OK - either I'd forgotten about that, or it's relatively new and I
> didn't notice the change (I stopped paying close attention to changes in
> the C++ standard around 2002, and only started paying attention again
> recently, when I was assigned to a project that uses C++).
> 
[...]
> 
>>> 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."
>>>
>>
>> The first sentence in that clause is "Each universal character name in
>> an identifier shall designate a character whose encoding in ISO/IEC
>> 10646 falls into one of the ranges specified in D.1." which suggests
>> that D.1 is the set of allowed characters in identifiers.
> 
> No, it only means that the UCNs described in D.1 are in the set, not
> that they constitute the entire set. Which is good, because D.1
> deliberately excludes the UCNs that corresponding the basic source
> character set. It would be pretty odd if you weren't allowed to use
> "identifier" as an identifier - it consists entirely of basic source
> characters.
I meant "the set of allowed /extended/ characters in identifiers", I 
thought this was obvious since we are only talking about extended chars 
here.

> 
>> However, I understand that you are saying that in combination with the
>> last sentence the condition of belonging to D.1. is a necessary but not
>> sufficient condition to be allowed in an identifier.
> 
> Correct. Basic source characters, and an implementation-defined set of
> extended characters, are also allowed.
> 
>> This seems to parse, but then how does it work with the possibility of
>> the character being one of "other implementation-defined characters"?
>> This ends up with D.1. being substantially useless.
> 
> No, D.1 is a list of the permitted UCNs, not extended characters.
> '\u03C0' is covered by D.1, but 'π' is not.

This is exactly my point with the C++ standard being more explicit (and 
more clear): C++ translation phase 1 converts all extended chars into 
UCNs, so that in the following 'π' is replaced by '\u03C0' in 
identifiers (and the rest of the source in general, the exception being 
raw string literals)
C leaves this unspecified.

  Implementations are
> permitted to define the map between extended source characters and UCNs.
> They are required to recognize extended source characters in identifiers
> as matching the corresponding UCNS. They are required to convert UCNs in
> character strings and string literals to the corresponding member of the
> execution character set (if any) during translation phase 5. But
> extended characters and UCNs are two distinct things, and you'll
> misunderstand many of the things the standard says about them if you
> misinterpret them as being the same.
> 

I know they are different things. Nevertheless I think it is pretty 
ambiguous that 'π' and '\u03C0' behave differently.

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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