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Re: Proper cast of function pointers

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Paavo Helde <eesnimi@osa.pri.ee> writes:

> 23.04.2024 14:44 Bonita Montero kirjutas:
>
>> Am 23.04.2024 um 13:31 schrieb Paavo Helde:
>>
>>> There is an old third-party library where some function pointers
>>> are casted to another type, then back to the original type before
>>> use.
>>> C++ standard says this is kosher, and there have never been any
>>> problems with actual behavior.  Alas, different versions and compile
>>> modes of g++ still produce warnings. ...
>>
>> That's because of the danger that someone calls the function-pointer
>> to which you cast.  Maybe you can cast through a void-pointer to sup-
>> press this warning.  But for me casting to a function pointer of a
>> differnt type doesn't make sense at at..
>> I think you confront yourself to uncertainties which actually never
>> happen.
>
> The function pointers are cast to a single type so that they can be
> stored in a common lookup array.  I could use a union there, but this
> would mean additional work with no real benefit, as the hypothetical
> "someone" could just as easily mess up the unions than the casting.

That depends on how the code is written.  The code can be written
so that making a mistake with the unions is both difficult and
unlikely.  To be continued downthread...

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Thread

Proper cast of function pointers Paavo Helde <eesnimi@osa.pri.ee> - 2024-04-23 14:31 +0300
  Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-23 13:44 +0200
    Re: Proper cast of function pointers Paavo Helde <eesnimi@osa.pri.ee> - 2024-04-23 21:33 +0300
      Re: Proper cast of function pointers David Brown <david.brown@hesbynett.no> - 2024-04-24 09:33 +0200
      Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-24 09:36 +0200
        Re: Proper cast of function pointers Paavo Helde <eesnimi@osa.pri.ee> - 2024-04-24 15:32 +0300
          Re: Proper cast of function pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-04-24 15:10 -0700
            Re: Proper cast of function pointers "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-04-24 15:14 -0700
            Re: Proper cast of function pointers Paavo Helde <eesnimi@osa.pri.ee> - 2024-04-25 08:37 +0300
              Re: Proper cast of function pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-04-25 15:04 -0700
          Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-25 11:19 +0200
            Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-25 11:39 +0200
              Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-25 11:48 +0200
                Re: Proper cast of function pointers Paavo Helde <eesnimi@osa.pri.ee> - 2024-04-25 22:22 +0300
                Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-26 07:52 +0200
      Re: Proper cast of function pointers Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-04-24 14:40 -0700
  Re: Proper cast of function pointers Markus Schaaf <mschaaf@elaboris.de> - 2024-04-23 14:23 +0200
    Re: Proper cast of function pointers David Brown <david.brown@hesbynett.no> - 2024-04-23 16:44 +0200
      Re: Proper cast of function pointers Markus Schaaf <mschaaf@elaboris.de> - 2024-04-23 17:00 +0200
        Re: Proper cast of function pointers David Brown <david.brown@hesbynett.no> - 2024-04-24 09:55 +0200
        Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-24 13:11 +0200
          Re: Proper cast of function pointers David Brown <david.brown@hesbynett.no> - 2024-04-24 13:15 +0200
      Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-24 13:10 +0200
        Re: Proper cast of function pointers David Brown <david.brown@hesbynett.no> - 2024-04-24 13:23 +0200
          Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-24 17:06 +0200
            Re: Proper cast of function pointers David Brown <david.brown@hesbynett.no> - 2024-04-24 17:59 +0200
              Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-24 19:36 +0200
    Re: Proper cast of function pointers Paavo Helde <eesnimi@osa.pri.ee> - 2024-04-23 21:50 +0300
      Re: Proper cast of function pointers Markus Schaaf <mschaaf@elaboris.de> - 2024-04-23 22:18 +0200
        Re: Proper cast of function pointers Markus Schaaf <mschaaf@elaboris.de> - 2024-04-23 22:22 +0200
        Re: Proper cast of function pointers Paavo Helde <eesnimi@osa.pri.ee> - 2024-04-23 23:33 +0300
  Re: Proper cast of function pointers David Brown <david.brown@hesbynett.no> - 2024-04-23 16:44 +0200
    Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-24 11:27 +0200
      Re: Proper cast of function pointers David Brown <david.brown@hesbynett.no> - 2024-04-24 13:14 +0200
        Re: Proper cast of function pointers Bo Persson <bo@bo-persson.se> - 2024-04-24 14:00 +0200
          Re: Proper cast of function pointers David Brown <david.brown@hesbynett.no> - 2024-04-24 16:41 +0200
        Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-24 17:07 +0200
          Re: Proper cast of function pointers David Brown <david.brown@hesbynett.no> - 2024-04-24 18:02 +0200
            Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-24 19:36 +0200
              Re: Proper cast of function pointers David Brown <david.brown@hesbynett.no> - 2024-04-24 21:18 +0200
                Re: Proper cast of function pointers Bonita Montero <Bonita.Montero@gmail.com> - 2024-04-25 09:50 +0200

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