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Groups > comp.lang.c > #112230
| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Type system protocols rest atop fundamental data |
| Date | 2017-06-14 17:02 -0700 |
| Organization | None to speak of |
| Message-ID | <lny3suazjn.fsf@kst-u.example.com> (permalink) |
| References | (2 earlier) <uhg0B.123559$Gx3.66049@fx45.am4> <87fuf28f8o.fsf@bsb.me.uk> <hRh0B.157156$524.104256@fx41.am4> <ln37b2ckt1.fsf@kst-u.example.com> <9Ij0B.155016$m76.119451@fx35.am4> |
bartc <bc@freeuk.com> writes:
> On 14/06/2017 22:37, Keith Thompson wrote:
>> bartc <bc@freeuk.com> writes:
>> [...]
>>> Enums are not a type.
>>
>> Incorrect. For example, given:
>> enum foo { zero, one };
>> `enum foo` is a type. Perhaps you meant something else.
>
> I considered enum to be just an int.
You were wrong. Enumerated types are integer types. `enum foo`
is a distinct type.
> Given these enums:
>
> typedef enum colours {red,green,blue} Colour;
> typedef enum days {mon, tue, wed} Day;
>
> Then only 2 of those 5 reject assigning a Day* to a Colour*.
Each enum type is compatible with some integer type. gcc treats Colour
and Day as compatible with unsigned int, but not with each other (which
is valid, type compatibility is not necessarily transitive).
My understanding is that Colour and Day are *not* compatible, even
if they're both compatible with the same integer type, and that
any conforming compiler must diagnose the assignment. (gcc does
in conforming mode.) I'm not 100% confident in that conclusion.
Did you invoke those 5 compilers in a standard-conforming mode?
If not, your results are meaningless.
> And when calling:
>
> void fn(Colour x){}
>
> then none of those compilers say anything when passing a Day type to
> such a function:
>
> Day d;
> fn(d);
There's an implicit conversion. That doesn't imply the types are the
same. Try passing an int to a function that with a double argument;
does the lack of a diagnostic imply that int and double are the same
type?
> Of course, none of them /can/ say anything when fn(wed) is used, as I
> don't think 'wed' has anything but int type.
Enumeration constants are of type int.
> So the effort to make enums a type is rather half-hearted, and doesn't
> go very far.
Nevertheless, enumerated types are types. N1570 6.2.5p16.
> Or possibly
>>> 11, if 'plain char' is considered different from unsigned or signed char.
>>
>> No "if" is necessary. Plain char *is* distinct from both unsigned char
>> and signed char.
>
> This:
>
> char *a;
> signed char *b;
> unsigned char *c;
>
> a=b;
> b=c;
> a=c;
>
> doesn't raise any errors with gcc. But does with some other compilers.
I get 3 warnings with "gcc -std=c11 -pedantic". Any results without
those options, or something similar, are irrelevant.
> (Another quirk for my collection I think. What possible use is having
> /three/ kinds of char? And why aren't there three kinds of int?)
At the moment, I'm not interested in discussing whether it's useful.
The fact is there are three character types.
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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Type system protocols rest atop fundamental data "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-06-14 06:14 -0700
Re: Type system protocols rest atop fundamental data "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-06-14 06:18 -0700
Re: Type system protocols rest atop fundamental data mark.bluemel@gmail.com - 2017-06-14 08:00 -0700
Re: Type system protocols rest atop fundamental data "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-06-14 08:06 -0700
Re: Type system protocols rest atop fundamental data bartc <bc@freeuk.com> - 2017-06-14 20:39 +0100
Re: Type system protocols rest atop fundamental data Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-14 21:51 +0100
Re: Type system protocols rest atop fundamental data bartc <bc@freeuk.com> - 2017-06-14 22:25 +0100
Re: Type system protocols rest atop fundamental data Keith Thompson <kst-u@mib.org> - 2017-06-14 14:37 -0700
Re: Type system protocols rest atop fundamental data bartc <bc@freeuk.com> - 2017-06-15 00:32 +0100
Re: Type system protocols rest atop fundamental data Keith Thompson <kst-u@mib.org> - 2017-06-14 17:02 -0700
Re: Type system protocols rest atop fundamental data bartc <bc@freeuk.com> - 2017-06-15 01:34 +0100
Re: Type system protocols rest atop fundamental data Robert Wessel <robertwessel2@yahoo.com> - 2017-06-14 20:28 -0500
Re: Type system protocols rest atop fundamental data raltbos@xs4all.nl (Richard Bos) - 2017-06-18 10:49 +0000
Re: Type system protocols rest atop fundamental data Keith Thompson <kst-u@mib.org> - 2017-06-14 20:02 -0700
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-15 10:29 +0200
Re: Type system protocols rest atop fundamental data bartc <bc@freeuk.com> - 2017-06-15 10:54 +0100
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-15 13:15 +0200
Re: Type system protocols rest atop fundamental data bartc <bc@freeuk.com> - 2017-06-15 13:51 +0100
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-15 16:13 +0200
Re: Type system protocols rest atop fundamental data Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-15 16:01 +0100
Re: Type system protocols rest atop fundamental data Keith Thompson <kst-u@mib.org> - 2017-06-15 09:27 -0700
Re: Type system protocols rest atop fundamental data raltbos@xs4all.nl (Richard Bos) - 2017-06-18 10:49 +0000
Re: Type system protocols rest atop fundamental data Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-16 23:35 -0700
Re: Type system protocols rest atop fundamental data Keith Thompson <kst-u@mib.org> - 2017-06-17 16:10 -0700
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-17 19:23 -0700
Re: Type system protocols rest atop fundamental data Ian Collins <ian-news@hotmail.com> - 2017-06-16 13:13 +1200
Re: Type system protocols rest atop fundamental data "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-06-15 18:44 -0700
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-16 13:42 +0200
Re: Type system protocols rest atop fundamental data Gareth Owen <gwowen@gmail.com> - 2017-06-16 20:20 +0100
Re: Type system protocols rest atop fundamental data Robert Wessel <robertwessel2@yahoo.com> - 2017-06-18 00:32 -0500
Re: Type system protocols rest atop fundamental data raltbos@xs4all.nl (Richard Bos) - 2017-06-18 11:06 +0000
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-18 15:26 +0200
Re: Type system protocols rest atop fundamental data bartc <bc@freeuk.com> - 2017-06-18 14:58 +0100
Re: Type system protocols rest atop fundamental data Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-15 01:42 +0100
Re: Type system protocols rest atop fundamental data bartc <bc@freeuk.com> - 2017-06-15 11:52 +0100
Re: Type system protocols rest atop fundamental data Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-15 16:07 +0100
Re: Type system protocols rest atop fundamental data Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-16 23:37 -0700
Re: Type system protocols rest atop fundamental data Keith Thompson <kst-u@mib.org> - 2017-06-15 09:52 -0700
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-15 10:36 -0700
Re: Type system protocols rest atop fundamental data scott@slp53.sl.home (Scott Lurndal) - 2017-06-15 17:58 +0000
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-15 11:48 -0700
Re: Type system protocols rest atop fundamental data scott@slp53.sl.home (Scott Lurndal) - 2017-06-15 19:01 +0000
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-15 12:29 -0700
Re: Type system protocols rest atop fundamental data Ian Collins <ian-news@hotmail.com> - 2017-06-16 13:47 +1200
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-15 19:33 -0700
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-15 13:02 -0700
Re: Type system protocols rest atop fundamental data "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-06-15 13:09 -0700
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-15 22:25 +0200
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-15 14:23 -0700
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-15 23:53 +0200
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-15 15:39 -0700
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-16 13:50 +0200
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-16 08:40 -0700
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-18 16:49 +0200
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-19 10:33 -0700
Re: Type system protocols rest atop fundamental data scott@slp53.sl.home (Scott Lurndal) - 2017-06-19 17:50 +0000
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-19 12:12 -0700
Re: Type system protocols rest atop fundamental data scott@slp53.sl.home (Scott Lurndal) - 2017-06-19 19:27 +0000
Re: Type system protocols rest atop fundamental data Ike Naar <ike@iceland.freeshell.org> - 2017-06-20 15:18 +0000
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-20 09:30 -0700
Re: Type system protocols rest atop fundamental data David Kleinecke <dkleinecke@gmail.com> - 2017-06-16 12:05 -0700
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-16 12:30 -0700
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-18 16:54 +0200
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-19 13:25 -0700
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-20 09:27 +0200
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-20 08:53 -0700
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-20 22:12 +0200
Re: Type system protocols rest atop fundamental data "Chris M. Thomasson" <invalid@invalid.invalid> - 2017-06-20 13:14 -0700
Re: Type system protocols rest atop fundamental data "Chris M. Thomasson" <invalid@invalid.invalid> - 2017-06-20 13:16 -0700
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-20 14:04 -0700
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-21 15:33 +0200
Re: Type system protocols rest atop fundamental data scott@slp53.sl.home (Scott Lurndal) - 2017-06-20 13:25 +0000
Re: Type system protocols rest atop fundamental data scott@slp53.sl.home (Scott Lurndal) - 2017-06-16 19:42 +0000
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-18 16:58 +0200
Re: Type system protocols rest atop fundamental data raltbos@xs4all.nl (Richard Bos) - 2017-06-17 19:18 +0000
Re: Type system protocols rest atop fundamental data Robert Wessel <robertwessel2@yahoo.com> - 2017-06-15 23:40 -0500
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-16 13:51 +0200
Re: Type system protocols rest atop fundamental data scott@slp53.sl.home (Scott Lurndal) - 2017-06-16 12:55 +0000
Re: Type system protocols rest atop fundamental data "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-06-14 14:23 -0700
Re: Type system protocols rest atop fundamental data Ian Collins <ian-news@hotmail.com> - 2017-06-16 13:48 +1200
Re: Type system protocols rest atop fundamental data "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-06-15 19:03 -0700
Re: Type system protocols rest atop fundamental data Ian Collins <ian-news@hotmail.com> - 2017-06-16 15:12 +1200
Re: Type system protocols rest atop fundamental data "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-06-15 20:20 -0700
Re: Type system protocols rest atop fundamental data Richard Heathfield <rjh@cpax.org.uk> - 2017-06-16 07:03 +0100
Re: Type system protocols rest atop fundamental data Ian Collins <ian-news@hotmail.com> - 2017-06-16 20:01 +1200
Re: Type system protocols rest atop fundamental data Richard Heathfield <rjh@cpax.org.uk> - 2017-06-16 19:21 +0100
Re: Type system protocols rest atop fundamental data "Chris M. Thomasson" <invalid@invalid.invalid> - 2017-06-16 12:07 -0700
Re: Type system protocols rest atop fundamental data Ian Collins <ian-news@hotmail.com> - 2017-06-17 16:18 +1200
Re: Type system protocols rest atop fundamental data Richard Heathfield <rjh@cpax.org.uk> - 2017-06-17 07:19 +0100
Re: Type system protocols rest atop fundamental data raltbos@xs4all.nl (Richard Bos) - 2017-06-17 19:19 +0000
Re: Type system protocols rest atop fundamental data Ian Collins <ian-news@hotmail.com> - 2017-06-18 08:29 +1200
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-17 18:49 -0700
Re: Type system protocols rest atop fundamental data Ian Collins <ian-news@hotmail.com> - 2017-06-18 16:18 +1200
Re: Type system protocols rest atop fundamental data Öö Tiib <ootiib@hot.ee> - 2017-06-18 06:28 -0700
Re: Type system protocols rest atop fundamental data Keith Thompson <kst-u@mib.org> - 2017-06-16 09:11 -0700
Re: Type system protocols rest atop fundamental data Tim Rentsch <txr@alumni.caltech.edu> - 2017-06-16 23:37 -0700
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-18 17:04 +0200
Re: Type system protocols rest atop fundamental data scott@slp53.sl.home (Scott Lurndal) - 2017-06-16 12:56 +0000
Re: Type system protocols rest atop fundamental data "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-06-16 07:10 -0700
Re: Type system protocols rest atop fundamental data GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-06-16 16:38 +0200
Re: Type system protocols rest atop fundamental data scott@slp53.sl.home (Scott Lurndal) - 2017-06-16 15:02 +0000
Re: Type system protocols rest atop fundamental data "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-06-16 08:11 -0700
Re: Type system protocols rest atop fundamental data David Brown <david.brown@hesbynett.no> - 2017-06-18 17:13 +0200
Re: Type system protocols rest atop fundamental data supercat@casperkitty.com - 2017-06-14 14:42 -0700
Re: Type system protocols rest atop fundamental data Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-14 21:32 +0100
Re: Type system protocols rest atop fundamental data "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-06-14 14:28 -0700
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