Re: Return statement: anything goes?

Newsgroups	comp.lang.c
Date	2017-03-11 10:59 -0800
References	(4 earlier) <oa0pct$9ll$1@dont-email.me> <87d1dnyi73.fsf@bsb.me.uk> <oa18ji$l75$1@dont-email.me> <877f3vyach.fsf@bsb.me.uk> <oa1dle$6qa$1@dont-email.me>
Message-ID	<b592c7be-be2e-49ec-8a43-668d64dcd412@googlegroups.com> (permalink)
Subject	Re: Return statement: anything goes?
From	jameskuyper@verizon.net

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On Saturday, March 11, 2017 at 12:57:52 PM UTC-5, Bart wrote:
> On 11/03/2017 17:47, Ben Bacarisse wrote:
> > BartC <bc@freeuk.com> writes:
> >
> >> On 11/03/2017 14:57, Ben Bacarisse wrote:
> 
> >>> But this raises the question of why you would implement C at all.
> >>
> >> Just for fun.
> >
> > Ah, I see.  You can do pretty much what you like then.
> 
> Well, it also has to work. That means compiling and running other 
> people's code /without changes/.

So, what other code are you willing to require your compiler to accept without changes? You've got to limit it in some fashion. If you include all conforming programs to the list, you've created an impossible requirement. Code that is entirely correct, containing no syntax errors, constraint violations or undefined behavior may still contain code that behaves differently when compiled by different compilers, due to things that the C standard leaves unspecified. As far as the author of deliberately non-portable code is concerned, if it has different behavior when translated by some other implementations than it would have when translated by the target implementation, that different behavior is incorrect behavior. Therefore, the only way your compiler could produce the correct behavior is by knowing how the intended target implementation would handle such code - which is something your compiler could not figure out from the code itself.

Do you want to restrict the code that your compiler is required to translate correctly to include all strictly conforming programs? If so, that comes close to requiring full conformance with the C standard. That would certainly be the case for the particular issues you raised in this thread.

"strictly conforming code" is pretty restrictive - there's very few real-world programs that qualify. Do you want your compiler to correctly translate a wider variety of programs? If so, you need to decide how wide a variety you want it to handle.

Thread

Return statement: anything goes? BartC <bc@freeuk.com> - 2017-03-10 19:13 +0000
  Re: Return statement: anything goes? John Bode <jfbode1029@gmail.com> - 2017-03-10 11:59 -0800
    Re: Return statement: anything goes? Keith Thompson <kst-u@mib.org> - 2017-03-10 12:34 -0800
  Re: Return statement: anything goes? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-10 20:17 +0000
    Re: Return statement: anything goes? bart4858@gmail.com - 2017-03-10 13:17 -0800
      Re: Return statement: anything goes? Ian Collins <ian-news@hotmail.com> - 2017-03-11 10:30 +1300
      Re: Return statement: anything goes? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-11 01:25 +0000
        Re: Return statement: anything goes? BartC <bc@freeuk.com> - 2017-03-11 12:11 +0000
          Re: Return statement: anything goes? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-11 14:57 +0000
            Re: Return statement: anything goes? BartC <bc@freeuk.com> - 2017-03-11 16:31 +0000
              Re: Return statement: anything goes? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-11 17:47 +0000
                Re: Return statement: anything goes? BartC <bc@freeuk.com> - 2017-03-11 17:57 +0000
                Re: Return statement: anything goes? jameskuyper@verizon.net - 2017-03-11 10:59 -0800
                Re: Return statement: anything goes? BartC <bc@freeuk.com> - 2017-03-11 19:34 +0000
                Re: Return statement: anything goes? jameskuyper@verizon.net - 2017-03-11 11:59 -0800
                Re: Return statement: anything goes? supercat@casperkitty.com - 2017-03-11 12:26 -0800
                Re: Return statement: anything goes? supercat@casperkitty.com - 2017-03-11 12:22 -0800
                Re: Return statement: anything goes? jameskuyper@verizon.net - 2017-03-11 12:42 -0800
                Re: Return statement: anything goes? supercat@casperkitty.com - 2017-03-11 13:01 -0800
                Re: Return statement: anything goes? Gordon Burditt <gordon@hammy.burditt.org> - 2017-03-13 16:25 -0500
            Re: Return statement: anything goes? Gareth Owen <gwowen@gmail.com> - 2017-03-11 16:43 +0000
              Re: Return statement: anything goes? BartC <bc@freeuk.com> - 2017-03-11 18:13 +0000
                Re: Return statement: anything goes? BartC <bc@freeuk.com> - 2017-03-11 18:27 +0000
          Re: Return statement: anything goes? gordonb.rlpr3@burditt.org (Gordon Burditt) - 2017-03-13 16:18 -0500
        Re: Return statement: anything goes? supercat@casperkitty.com - 2017-03-11 12:44 -0800
      Re: Return statement: anything goes? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-03-11 07:43 -0800
        Re: Return statement: anything goes? BartC <bc@freeuk.com> - 2017-03-11 18:34 +0000
          Re: Return statement: anything goes? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-03-11 10:43 -0800
  Re: Return statement: anything goes? Keith Thompson <kst-u@mib.org> - 2017-03-10 12:27 -0800
  Re: Return statement: anything goes? Noob <root@127.0.0.1> - 2017-03-10 22:06 +0100
    Re: Return statement: anything goes? bart4858@gmail.com - 2017-03-10 13:26 -0800
      Re: Return statement: anything goes? antispam@math.uni.wroc.pl - 2017-03-12 05:29 +0000
        Re: Return statement: anything goes? BartC <bc@freeuk.com> - 2017-03-12 10:52 +0000
          Re: Return statement: anything goes? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-12 12:19 +0000
            Re: Return statement: anything goes? BartC <bc@freeuk.com> - 2017-03-12 12:51 +0000

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