Re: compiling [old] c code

From	Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups	comp.lang.c
Subject	Re: compiling [old] c code
Date	2019-01-23 02:12 +0000
Organization	A noiseless patient Spider
Message-ID	<87tvi0xgtu.fsf@bsb.me.uk> (permalink)
References	(6 earlier) <048927d3-9039-4cce-84a2-1eec71d65eb5@googlegroups.com> <87fttkzllq.fsf@bsb.me.uk> <53d95acc-3eb2-4bee-9b44-6c4a2fd638f3@googlegroups.com> <875zugz4yy.fsf@bsb.me.uk> <4eb0bf48-2998-4d5c-9ed8-b1b5edf5c5f4@googlegroups.com>

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fir <profesor.fir@gmail.com> writes:

> W dniu wtorek, 22 stycznia 2019 23:45:50 UTC+1 użytkownik Ben Bacarisse napisał:
>> fir <profesor.fir@gmail.com> writes:
>> 
>> > W dniu wtorek, 22 stycznia 2019 17:46:35 UTC+1 użytkownik Ben Bacarisse napisał:
>> >> fir <profesor.fir@gmail.com> writes:
>> >> 
>> >> > W dniu poniedziałek, 21 stycznia 2019 19:34:08 UTC+1 użytkownik Ben Bacarisse napisał:
>> <snip>
>> >> >> Apart form the "big union" idea that's already been mentioned, you coud
>> >> >> try a macro:
>> >> >> 
>> >> >> #define PTR(p, s) ((struct s *)(p))
>> >> >> 
>> >> >> and re-write things like
>> >> >> 
>> >> >>   ttype = t->vtype;
>> >> >> 
>> >> >> as
>> >> >> 
>> >> >>   ttype = PTR(t, varblock)->vtype;
>> >> >> 
>> >> >> You might even be able to automate this a bit by using something like
>> >> >> Perl to record what structs have what members.
>> >> >
>> >> > it seems to me that he dont need to rewrite field acceses only
>> >> > maybe put
>> >> >
>> >> > ptr = (struct some*) ptr; //?
>> >> >
>> >> > in thet few places
>> >> 
>> >> This would be a constraint violation and yet would achieve nothing.
>> >> 
>> > what do you mean? you cant cast pointer
>> > on another type of pointer?
>> 
>> ptr is of type int *.  Assigning a struct some * to an int * object is
>> an error.  C, however, does not really have errors -- it has situations
>> that compiler must report.  These are called constraint violations and
>> your assignment is an example of one.
>> 
>> Your suggestion does not achieve anything because it does not solve the
>> problem.  You can't access the struct member after the assignment any
>> more that you could before.
>> 
> well it may be, i dont remember such (in a way) silly details (details
> that can be seen as silly in some way)

No, ptr = (struct some*) ptr; does nothing but make the program
undefined.

<snip>
-- 
Ben.

Thread

compiling all c code fiziqs@gmail.com - 2019-01-20 14:51 -0800
  Re: compiling all c code Richard Damon <Richard@Damon-Family.org> - 2019-01-20 18:41 -0500
  Re: compiling all c code gazelle@shell.xmission.com (Kenny McCormack) - 2019-01-20 23:42 +0000
  Re: compiling all c code Geoff <geoff@invalid.invalid> - 2019-01-20 16:44 -0800
    Re: compiling all c code fiziqs@gmail.com - 2019-01-21 02:36 -0800
      Re: compiling [old] c code Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-21 12:20 +0000
        Re: compiling [old] c code fiziqs@gmail.com - 2019-01-21 04:58 -0800
          Re: compiling [old] c code Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-21 18:33 +0000
            Re: compiling [old] c code fir <profesor.fir@gmail.com> - 2019-01-22 04:21 -0800
              Re: compiling [old] c code Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-22 16:46 +0000
                Re: compiling [old] c code fir <profesor.fir@gmail.com> - 2019-01-22 10:35 -0800
                Re: compiling [old] c code Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-22 22:45 +0000
                Re: compiling [old] c code fir <profesor.fir@gmail.com> - 2019-01-22 14:58 -0800
                Re: compiling [old] c code Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-23 02:12 +0000
                Re: compiling [old] c code fir <profesor.fir@gmail.com> - 2019-01-23 00:59 -0800
        Re: compiling [old] c code fir <profesor.fir@gmail.com> - 2019-01-22 03:34 -0800
          Re: compiling [old] c code fir <profesor.fir@gmail.com> - 2019-01-22 04:08 -0800
      Re: compiling all c code Keith Thompson <kst-u@mib.org> - 2019-01-21 14:23 -0800

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