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Groups > comp.lang.c > #102908

Re: C declarations

From Keith Thompson <kst-u@mib.org>
Newsgroups comp.lang.c
Subject Re: C declarations
Date 2017-02-01 08:08 -0800
Organization None to speak of
Message-ID <lnbmul99m9.fsf@kst-u.example.com> (permalink)
References (5 earlier) <efdemaFhgsiU2@mid.individual.net> <o6s8i9$cuj$1@dont-email.me> <o6sha6$a6l$1@dont-email.me> <o6slob$pkf$1@dont-email.me> <o6snb9$v37$1@dont-email.me>

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BartC <bc@freeuk.com> writes:
[...]
> (I notice you shouldn't use _Complex by itself, but have to combine it 
> with float or double, which I hadn't realised. Yet usually you can. More 
> laxity on the part of compilers.)

That is unfortunate.

With gcc 6.2, this:

    _Complex x;

compiles with no warning by default.  With "-pedantic", it warns:

    warning: ISO C does not support plain ‘complex’ meaning ‘double complex’ [-Wpedantic]

C90 did not have complex at all.  C99, which introduced the _Complex
keyword, did not permit it by itself; it's a type specifier that has to
be associated with "float", "double", or "long double".  There is no
standard version of the language in which that declaration is valid.

My guess is that it was proposed as equivalent to `double _Complex` some
time during the development of the C99 standard, and gcc implemented
support for it.

IMHO gcc *should* at least warn about it by default.  But then you
probably shouldn't invoke gcc with default arguments if you care about
catching errors in your code.

-- 
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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C declarations BartC <bc@freeuk.com> - 2017-01-30 13:00 +0000
  Re: C declarations David Brown <david.brown@hesbynett.no> - 2017-01-30 14:25 +0100
    Re: C declarations Keith Thompson <kst-u@mib.org> - 2017-01-30 11:42 -0800
  Re: C declarations Andrey Tarasevich <andreytarasevich@hotmail.com> - 2017-01-31 13:46 -0800
    Re: C declarations BartC <bc@freeuk.com> - 2017-01-31 22:13 +0000
      Re: C declarations Andrey Tarasevich <andreytarasevich@hotmail.com> - 2017-01-31 16:43 -0800
        Re: C declarations Andrey Tarasevich <andreytarasevich@hotmail.com> - 2017-01-31 17:06 -0800
      Re: C declarations Ian Collins <ian-news@hotmail.com> - 2017-02-01 17:58 +1300
        Re: C declarations luser droog <luser.droog@gmail.com> - 2017-01-31 22:42 -0800
          Re: C declarations Ian Collins <ian-news@hotmail.com> - 2017-02-01 19:48 +1300
            Re: C declarations Robert Wessel <robertwessel2@yahoo.com> - 2017-02-01 01:18 -0600
            Re: C declarations David Brown <david.brown@hesbynett.no> - 2017-02-01 10:10 +0100
              Re: C declarations BartC <bc@freeuk.com> - 2017-02-01 11:39 +0000
                Re: C declarations David Brown <david.brown@hesbynett.no> - 2017-02-01 13:55 +0100
                Re: C declarations BartC <bc@freeuk.com> - 2017-02-01 13:22 +0000
                Re: C declarations David Brown <david.brown@hesbynett.no> - 2017-02-01 16:30 +0100
                Re: C declarations Keith Thompson <kst-u@mib.org> - 2017-02-01 08:15 -0800
                Re: C declarations supercat@casperkitty.com - 2017-02-01 08:44 -0800
                Re: C declarations David Brown <david.brown@hesbynett.no> - 2017-02-01 20:56 +0100
                Re: C declarations supercat@casperkitty.com - 2017-02-01 08:29 -0800
                Re: C declarations BartC <bc@freeuk.com> - 2017-02-01 17:24 +0000
                Re: C declarations fir <profesor.fir@gmail.com> - 2017-02-01 09:55 -0800
                Re: C declarations BartC <bc@freeuk.com> - 2017-02-01 18:44 +0000
                Re: C declarations Keith Thompson <kst-u@mib.org> - 2017-02-01 11:03 -0800
                Re: C declarations fir <profesor.fir@gmail.com> - 2017-02-01 12:26 -0800
                Re: C declarations fir <profesor.fir@gmail.com> - 2017-02-01 13:03 -0800
                Re: C declarations fir <profesor.fir@gmail.com> - 2017-02-01 13:12 -0800
                Re: C declarations fir <profesor.fir@gmail.com> - 2017-02-03 16:07 -0800
                Re: C declarations Keith Thompson <kst-u@mib.org> - 2017-02-01 10:44 -0800
                Re: C declarations jameskuyper@verizon.net - 2017-02-01 11:08 -0800
                Re: C declarations Keith Thompson <kst-u@mib.org> - 2017-02-01 10:40 -0800
                Re: C declarations BartC <bc@freeuk.com> - 2017-02-01 17:04 +0000
                Re: C declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-01 19:58 +0000
                Re: C declarations BartC <bc@freeuk.com> - 2017-02-01 21:23 +0000
                Re: C declarations Keith Thompson <kst-u@mib.org> - 2017-02-01 08:08 -0800
                Re: C declarations Andrey Tarasevich <andreytarasevich@hotmail.com> - 2017-02-01 12:45 -0800
  Re: C declarations Andrey Tarasevich <andreytarasevich@hotmail.com> - 2017-03-06 11:19 -0800
    Re: C declarations Keith Thompson <kst-u@mib.org> - 2017-03-06 11:27 -0800

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