Re: diagnosing C errors, was Alternative C compilers on x86_64 Linux?

From	Kaz Kylheku <221-501-9011@kylheku.com>
Newsgroups	comp.compilers
Subject	Re: diagnosing C errors, was Alternative C compilers on x86_64 Linux?
Date	2016-09-09 16:06 +0000
Organization	Aioe.org NNTP Server
Message-ID	<16-09-020@comp.compilers> (permalink)
References	<16-09-001@comp.compilers> <16-09-002@comp.compilers> <16-09-008@comp.compilers> <16-09-019@comp.compilers>

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On 2016-09-09, BartC <bc@freeuk.com> wrote:
> On 06/09/2016 01:26, alexfrunews@gmail.com wrote:
>> On Sunday, September 4, 2016 at 3:56:56 PM UTC-7, jacobnavia wrote:
>>> Why should they care? If you write duplicate switch cases its not their
>>> fault, its yours.
>>
>> It is a constraint violation, and a trivial one, that the compiler
>> must identify and report instead of silently producing code that is
>> broken or appears to work by chance.
>
> This is C. There are already plenty of things that it lets through that
> are probably errors, and which are likely to crash the program.

That's true. The major real-world consequence of not producing
an ISO-C required diagnostic is that the code will fail to compile
on compilers other than the one with which it was developed.

Though you may have some dead code in a switch statement, and that could
be a bug, on the other hand, you test the code.  It's not a bug if there
is no external test case which reproduces an issue.

And that brings us to Aharon's original point about looking for
a compiler that can be used for *development*.  A compiler used for
development should have excellent diagnostics, which helps make the code
cleanly portable to other compilers.

> By contrast, an inadvertent duplicate case label is a 'soft' error; the
> program just won't give the expected results.

Or, as I argue about, there might in fact be no bug: the correct fix
might in fact be just to remove the duplicate label and all the code
under it.

Some ISO C required diagnostics do help uncover real errors, which
helps, in spite of the C language having lots of pitfalls and holes.

Imagine if you could assign any scalar type to any other without needing
a cast, and with no diagnostic: double x = "abc", and so on.
Or call functions without any parameter checking.

The type checking in C does a lot for improving the reliability of C
programs, even though it falls far short of repairing all the holes
and pitfalls.

Thread

Alternative C compilers on x86_64 Linux? arnold@skeeve.com (Aharon Robbins) - 2016-09-02 03:01 +0000
  Re: Alternative C compilers on x86_64 Linux? jacobnavia <jacob@jacob.remcomp.fr> - 2016-09-05 00:20 +0200
    Re: Alternative C compilers on x86_64 Linux? alexfrunews@gmail.com - 2016-09-05 17:26 -0700
      Re: diagnosing C errors, was Alternative C compilers on x86_64 Linux? BartC <bc@freeuk.com> - 2016-09-09 12:31 +0100
        Re: diagnosing C errors, was Alternative C compilers on x86_64 Linux? Kaz Kylheku <221-501-9011@kylheku.com> - 2016-09-09 16:06 +0000
        Re: diagnosing C errors, was Alternative C compilers on x86_64 Linux? Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2016-09-10 00:38 +0200
  Re: Alternative C compilers on x86_64 Linux? Nemo <nemo@invalid.invalid> - 2016-09-04 18:32 -0400
  Re: Alternative C compilers on x86_64 Linux? Kaz Kylheku <221-501-9011@kylheku.com> - 2016-09-04 23:48 +0000
  Re: Alternative C compilers on x86_64 Linux? BartC <bc@freeuk.com> - 2016-09-05 13:19 +0100
    Re: Alternative C compilers on x86_64 Linux? Kaz Kylheku <221-501-9011@kylheku.com> - 2016-09-06 02:15 +0000
      Re: Alternative C compilers on x86_64 Linux? BartC <bc@freeuk.com> - 2016-09-06 21:35 +0100
        Re: dead code or otherwise, was Alternative C compilers on x86_64 Linux? George Neuner <gneuner2@comcast.net> - 2016-09-08 11:58 -0400
          Re: dead code or otherwise, was Alternative C compilers on x86_64 Linux? Kaz Kylheku <221-501-9011@kylheku.com> - 2016-09-08 22:54 +0000
            Re: dead code or otherwise, was Alternative C compilers on x86_64 Linux? George Neuner <gneuner2@comcast.net> - 2016-09-09 00:51 -0400
              Re: dead code or otherwise, was Alternative C compilers on x86_64 Linux? Kaz Kylheku <221-501-9011@kylheku.com> - 2016-09-09 06:05 +0000
                Re: dead code or otherwise, was Alternative C compilers on x86_64 Linux? George Neuner <gneuner2@comcast.net> - 2016-09-09 14:02 -0400
                Re: dead code or otherwise, was Alternative C compilers on x86_64 Linux? Kaz Kylheku <221-501-9011@kylheku.com> - 2016-09-09 19:57 +0000
      Re: duplicate cases, was Alternative C compilers on x86_64 Linux? Andy Walker <anw@cuboid.co.uk> - 2016-09-07 17:01 +0100
  Re: Alternative C compilers on x86_64 Linux? Florian Weimer <fw@deneb.enyo.de> - 2016-09-05 20:06 +0200
  Re: Alternative C compilers on x86_64 Linux? alexfrunews@gmail.com - 2016-09-05 17:22 -0700
    Re: Alternative C compilers on x86_64 Linux? Kaz Kylheku <221-501-9011@kylheku.com> - 2016-09-06 02:18 +0000
  Re: Alternative C compilers on x86_64 Linux? rockbrentwood@gmail.com - 2016-09-07 17:00 -0700
  Re: Alternative C compilers on x86_64 Linux? arnold@skeeve.com (Aharon Robbins) - 2016-09-12 18:42 +0000
    Re: Alternative C compilers on x86_64 Linux? BartC <bc@freeuk.com> - 2016-09-12 22:37 +0100
      Re: Alternative C compilers on x86_64 Linux? arnold@skeeve.com (Aharon Robbins) - 2016-09-13 17:35 +0000
        Re: Alternative C compilers on x86_64 Linux? arnold@skeeve.com (Aharon Robbins) - 2016-09-14 18:14 +0000
  Re: Alternative C compilers on x86_64 Linux? rugxulo@gmail.com - 2016-09-26 15:29 -0700
    Re: Alternative C compilers on x86_64 Linux? arnold@skeeve.com (Aharon Robbins) - 2016-09-27 05:40 +0000
      Re: Alternative C compilers on x86_64 Linux? rugxulo@gmail.com - 2016-09-27 16:36 -0700
        Re: Alternative C compilers on x86_64 Linux? BartC <bc@freeuk.com> - 2016-09-28 18:16 +0100
          Re: Alternative C compilers on x86_64 Linux? BartC <bc@freeuk.com> - 2016-09-29 14:03 +0100
            Re: Alternative C compilers on x86_64 Linux? George Neuner <gneuner2@comcast.net> - 2016-09-29 22:57 -0400
            Re: Alternative C compilers on x86_64 Linux? Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2016-09-30 05:03 +0200
              Re: Alternative C compilers on x86_64 Linux? BartC <bc@freeuk.com> - 2016-09-30 12:00 +0100
                Re: Alternative C compilers on x86_64 Linux? Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2016-09-30 20:15 +0200
                Re: Alternative C compilers on x86_64 Linux? BartC <bc@freeuk.com> - 2016-10-01 22:17 +0100
            Re: Alternative C compilers on x86_64 Linux? BartC <bc@freeuk.com> - 2016-09-30 12:28 +0100
              Re: Alternative C compilers on x86_64 Linux? BartC <bc@freeuk.com> - 2016-10-17 22:49 +0100
        Re: Alternative C compilers on x86_64 Linux? George Neuner <gneuner2@comcast.net> - 2016-09-28 21:24 -0400
      Re: Alternative C compilers on x86_64 Linux? George Neuner <gneuner2@comcast.net> - 2016-09-28 01:01 -0400
        Re: Alternative C compilers on x86_64 Linux? arnold@skeeve.com (Aharon Robbins) - 2016-09-29 02:55 +0000
      Re: Alternative C compilers on x86_64 Linux? arnold@skeeve.com - 2016-09-29 05:30 -0600
        Re: Alternative C compilers on x86_64 Linux? arnold@skeeve.com (Aharon Robbins) - 2016-09-30 10:13 +0000

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