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Re: How to fix: [-Wformat-nonliteral]

From Keith Thompson <kst-u@mib.org>
Newsgroups comp.lang.c
Subject Re: How to fix: [-Wformat-nonliteral]
Date 2017-04-13 08:43 -0700
Organization None to speak of
Message-ID <lnh91suxd5.fsf@kst-u.example.com> (permalink)
References (9 earlier) <oci7n4$l8l$1@dont-email.me> <aa3e8f39-85a0-4c75-9adc-bc79d54005f5@googlegroups.com> <ocm91l$nkc$1@dont-email.me> <lntw5tun1p.fsf@kst-u.example.com> <45db5042-80fe-4900-9724-1bf2e3f7092c@googlegroups.com>

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supercat@casperkitty.com writes:
> On Wednesday, April 12, 2017 at 8:14:05 PM UTC-5, Keith Thompson wrote:
>> Wouldn't it be better to support 32-bit "float" and reject "double"?
>> It's non-conforming either way, but it would cleanly reject code that
>> uses "double" and quite reasonably expects it to be wider than 32
>> bits.
>
> The Standard specifies that arguments to variadic functions get converted
> to type "double".

That's a good point.  On the other hand, it might not apply to the tiny
8-bit system being discussed.  I don't know whether it supports printf,
or specifically printf for floating-point types.

>                    The Standard provides a means by which implementations
> can report the level of precision that their "double" types support, but
> specifies a minimum which requires using longer than a 32-bit significand.

True, but we're talking about a non-conforming implementation.  The
question is which violation is better: making double 32 bits, or not
supporting double at all.  The assumption is that the target supports
32-bit floating-point, but nothing wider (and it's not worthwhile to
support wider floating-point in software).

You can make double 32 bits, or you can drop support for double, change
the promotion rules, and change the type of floating-point constants.
Perhaps making double 32 bits is less intrusive.

And if you make double 32 bits, what about long double?

-- 
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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How to fix: [-Wformat-nonliteral] MehdiAmini <atorrses@gmail.com> - 2017-04-07 12:20 +0430
  Re: How to fix: [-Wformat-nonliteral] Barry Schwarz <schwarzb@dqel.com> - 2017-04-07 01:28 -0700
  Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-07 11:58 +0200
    Re: How to fix: [-Wformat-nonliteral] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-04-07 11:43 +0100
      Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-07 13:35 +0200
    Re: How to fix: [-Wformat-nonliteral] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-04-07 13:50 +0100
      Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-07 15:54 +0200
        Re: How to fix: [-Wformat-nonliteral] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-04-07 19:35 +0100
          Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-08 13:41 +0200
            Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-10 13:52 -0700
              Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-11 00:18 +0200
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-10 15:43 -0700
                Re: How to fix: [-Wformat-nonliteral] Keith Thompson <kst-u@mib.org> - 2017-04-10 16:10 -0700
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-10 16:26 -0700
                Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-11 11:33 +0200
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-11 08:37 -0700
                Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-13 00:20 +0200
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-12 15:55 -0700
                Re: How to fix: [-Wformat-nonliteral] Keith Thompson <kst-u@mib.org> - 2017-04-12 18:17 -0700
                Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-14 12:27 +0200
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-14 11:57 -0700
                Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-17 18:08 +0200
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-17 09:38 -0700
                Re: How to fix: [-Wformat-nonliteral] Keith Thompson <kst-u@mib.org> - 2017-04-12 18:13 -0700
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-13 07:37 -0700
                Re: How to fix: [-Wformat-nonliteral] Keith Thompson <kst-u@mib.org> - 2017-04-13 08:43 -0700
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-13 11:24 -0700
                Re: How to fix: [-Wformat-nonliteral] Keith Thompson <kst-u@mib.org> - 2017-04-13 11:49 -0700
                Re: How to fix: [-Wformat-nonliteral] Robert Wessel <robertwessel2@yahoo.com> - 2017-04-13 14:43 -0500
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-13 13:26 -0700
                Re: How to fix: [-Wformat-nonliteral] Keith Thompson <kst-u@mib.org> - 2017-04-13 13:32 -0700
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-13 14:27 -0700
                Re: How to fix: [-Wformat-nonliteral] Robert Wessel <robertwessel2@yahoo.com> - 2017-04-13 17:39 -0500
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-13 16:16 -0700
                Re: How to fix: [-Wformat-nonliteral] Tim Rentsch <txr@alumni.caltech.edu> - 2017-04-16 17:53 -0700
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-13 13:19 -0700
                Re: How to fix: [-Wformat-nonliteral] Tim Rentsch <txr@alumni.caltech.edu> - 2017-04-16 17:49 -0700
                Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-17 18:14 +0200
                Re: How to fix: [-Wformat-nonliteral] Keith Thompson <kst-u@mib.org> - 2017-04-17 11:54 -0700
                Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-17 22:41 +0200
                Re: How to fix: [-Wformat-nonliteral] Keith Thompson <kst-u@mib.org> - 2017-04-17 15:02 -0700
                Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-14 12:40 +0200
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-14 12:10 -0700
                Re: How to fix: [-Wformat-nonliteral] Keith Thompson <kst-u@mib.org> - 2017-04-14 13:22 -0700
                Re: How to fix: [-Wformat-nonliteral] supercat@casperkitty.com - 2017-04-14 17:14 -0700
                Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-13 00:20 +0200
      Re: How to fix: [-Wformat-nonliteral] MehdiAmini <atorrses@gmail.com> - 2017-04-07 20:29 +0430
        Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-07 18:42 +0200
          Re: How to fix: [-Wformat-nonliteral] MehdiAmini <atorrses@gmail.com> - 2017-04-08 08:04 +0430
            Re: How to fix: [-Wformat-nonliteral] Richard Heathfield <rjh@cpax.org.uk> - 2017-04-08 07:51 +0100
              Re: How to fix: [-Wformat-nonliteral] MehdiAmini <atorrses@gmail.com> - 2017-04-08 12:11 +0430
                Re: How to fix: [-Wformat-nonliteral] Richard Heathfield <rjh@cpax.org.uk> - 2017-04-08 11:38 +0100
                Re: How to fix: [-Wformat-nonliteral] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-04-08 18:52 +0100
            Re: How to fix: [-Wformat-nonliteral] David Brown <david.brown@hesbynett.no> - 2017-04-08 13:48 +0200
              Re: How to fix: [-Wformat-nonliteral] MehdiAmini <atorrses@gmail.com> - 2017-04-08 20:34 +0430

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