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Re: A question about if constexpr

From Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups comp.lang.c++
Subject Re: A question about if constexpr
Date 2019-11-28 13:52 -0800
Organization A noiseless patient Spider
Message-ID <86d0dbact8.fsf@linuxsc.com> (permalink)
References <9d930f21-6639-49a3-8ef2-5de724f18255@googlegroups.com>

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Daniel <danielaparker@gmail.com> writes:

> Consider
>
> #include <string>
> #include <iostream>
>
> int main()
> {
>     constexpr int n = 1;
>     constexpr int m = 10;
>     std::string s = "abcd";
>
>     if (n < m || s.empty())
>     {
>         std::cout << "ok\n";
>     }
> }
>
> Is it reasonable that vs2019 produces a warning
>
> warning C4127:  conditional expression is constant
> consider using 'if constexpr' statement instead

Let me rephrase your question as a multiple choice:

   "A compiler operating under default option settings
    produces this warning message for the above program.
    Would you be more likely to describe this choice as

       (A) reasonable, or

       (B) monumentally stupid?"

Asked like this, my answer would be (B).

There are, I am sure, a large number of related questions,
for which I expect I would give various answers depending
on the particular question.

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Thread

A question about if constexpr Daniel <danielaparker@gmail.com> - 2019-11-27 05:45 -0800
  Re: A question about if constexpr "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2019-11-27 15:03 +0100
    Re: A question about if constexpr Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-11-29 16:33 +0000
      Re: A question about if constexpr Öö Tiib <ootiib@hot.ee> - 2019-11-29 16:52 -0800
        Re: A question about if constexpr David Brown <david.brown@hesbynett.no> - 2019-11-30 12:03 +0100
          Re: A question about if constexpr Öö Tiib <ootiib@hot.ee> - 2019-11-30 03:47 -0800
            Re: A question about if constexpr David Brown <david.brown@hesbynett.no> - 2019-11-30 15:08 +0100
  Re: A question about if constexpr Sam <sam@email-scan.com> - 2019-11-27 18:40 -0500
    Re: A question about if constexpr Öö Tiib <ootiib@hot.ee> - 2019-11-27 23:16 -0800
      Re: A question about if constexpr Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-11-29 16:35 +0000
        Re: A question about if constexpr Öö Tiib <ootiib@hot.ee> - 2019-11-29 16:41 -0800
    Re: A question about if constexpr David Brown <david.brown@hesbynett.no> - 2019-11-28 10:24 +0100
      Re: A question about if constexpr Bo Persson <bo@bo-persson.se> - 2019-11-28 11:58 +0100
        Re: A question about if constexpr David Brown <david.brown@hesbynett.no> - 2019-11-28 12:37 +0100
        Re: A question about if constexpr Robert Wessel <robertwessel2@yahoo.com> - 2019-11-28 14:04 -0600
          Re: A question about if constexpr David Brown <david.brown@hesbynett.no> - 2019-11-29 09:23 +0100
            Re: A question about if constexpr Robert Wessel <robertwessel2@yahoo.com> - 2019-11-29 14:42 -0600
      Re: A question about if constexpr Daniel <danielaparker@gmail.com> - 2019-11-28 21:09 -0800
        Re: A question about if constexpr "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2019-11-29 07:41 +0100
        Re: A question about if constexpr Öö Tiib <ootiib@hot.ee> - 2019-11-28 23:50 -0800
          Re: A question about if constexpr David Brown <david.brown@hesbynett.no> - 2019-11-29 09:38 +0100
            Re: A question about if constexpr Öö Tiib <ootiib@hot.ee> - 2019-11-29 17:15 -0800
              Re: A question about if constexpr Paavo Helde <myfirstname@osa.pri.ee> - 2019-11-30 08:19 +0200
                Re: A question about if constexpr Ned Latham <nedlatham@woden.valhalla.oz> - 2019-11-30 00:24 -0600
                Re: A question about if constexpr Öö Tiib <ootiib@hot.ee> - 2019-11-30 02:13 -0800
                Re: A question about if constexpr Ned Latham <nedlatham@woden.valhalla.oz> - 2019-11-30 04:56 -0600
                Re: A question about if constexpr Öö Tiib <ootiib@hot.ee> - 2019-11-30 03:20 -0800
                Re: A question about if constexpr Ned Latham <nedlatham@woden.valhalla.oz> - 2019-11-30 05:38 -0600
                Re: A question about if constexpr Öö Tiib <ootiib@hot.ee> - 2019-11-30 04:57 -0800
                Re: A question about if constexpr Ned Latham <nedlatham@woden.valhalla.oz> - 2019-11-30 09:46 -0600
                Re: A question about if constexpr Öö Tiib <ootiib@hot.ee> - 2019-11-30 11:09 -0800
                Re: A question about if constexpr Ned Latham <nedlatham@woden.valhalla.oz> - 2019-11-30 20:03 -0600
                Re: A question about if constexpr Öö Tiib <ootiib@hot.ee> - 2019-11-30 23:43 -0800
                Re: A question about if constexpr Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-01 04:56 -0600
                Re: A question about if constexpr Christian Gollwitzer <auriocus@gmx.de> - 2019-12-01 18:33 +0100
                Re: A question about if constexpr Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-01 19:27 -0600
                Re: A question about if constexpr boltar@nowhere.co.uk - 2019-12-02 08:34 +0000
                Re: A question about if constexpr Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-02 04:21 -0600
                Re: A question about if constexpr boltar@nowhere.co.uk - 2019-12-02 08:33 +0000
                Re: A question about if constexpr Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-12-03 17:05 +0000
                Re: A question about if constexpr boltar@nowhere.co.uk - 2019-12-03 17:09 +0000
                Re: A question about if constexpr Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-12-03 18:03 +0000
                Re: A question about if constexpr boltar@nowhere.co.uk - 2019-12-04 16:49 +0000
                Re: A question about if constexpr Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-12-04 18:36 +0000
                Re: A question about if constexpr boltar@nowhere.co.uk - 2019-12-05 12:51 +0000
        Re: A question about if constexpr David Brown <david.brown@hesbynett.no> - 2019-11-29 09:30 +0100
      Re: A question about if constexpr Paavo Helde <myfirstname@osa.pri.ee> - 2019-11-29 10:51 +0200
  Re: A question about if constexpr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-28 13:52 -0800
  Re: A question about if constexpr Bonita Montero <Bonita.Montero@gmail.com> - 2019-12-01 14:42 +0100

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