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Re: OT: One of Anton's papers makes Hacker News

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From Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm>
Newsgroups comp.lang.forth
Subject Re: OT: One of Anton's papers makes Hacker News
Date Fri, 4 Mar 2016 21:01:45 -0500
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On Thu, 03 Mar 2016 16:24:16 -0800
Paul Rubin <no.email@nospam.invalid> wrote:

> Under the title "what every compiler writer should know about
> programmers".  The paper criticizes various compiler responses to the
> presence of undefined behaviour in C programs, a topic that has come
> up here in CLF several times.
> 
> Paper:
> [link]

I don't have time to read all of your paper, but
clearly you still fail to understand the basics of C.
You should really, really have a C expert review
this stuff first before publishing it ...

I got to this part, which I felt I needed to comment
on as yet another example of why you still don't
understand C:

"However, this implementation is C*, but not ``C'',
because p<q is not defined in ``C'' if p and q point
to different objects."

That is a completely wrong conclusion.

Look at how memmove() is declared:

 void *memmove(void *dest, const void *src, size_t n)

Here, p represents dest, and q represents src.
So, p<q represents dest<src.

What objects do dest or src point to?

The answer to that question is: none.  They point to
no objects.  So, what objects are you referring to? ...

Neither dest nor src point to any data object in C.
There is  *NO* data type associated with dest or src.
That's what "void" means.  These are raw pointers
to memory without any C object associated with them.
The place where memmove is called may have declared
data types passed, but nothing is associated with
dest and src once they've been through parameter
type conversion to be passed into memmove().

If there is no type associated with dest or
src, then there can be no object associated
with dest or src.  Therefore, the fact that
p<q is not defined for different objects is
irrelevant here since there are no objects
involved.  p and q, representing, dest and
src, work on raw memory which is objectless.


And, you continue with the same erroneous understanding:

"However, a ``C'' compiler might assume that src and
dest point to the same object, ..."

It, the C compiler, can do no such thing.  dest
and src  **DO NOT**  point to _any_ valid C object.
That is what "void" means in C.  The compiler
cannot assume anything about any object from dest or
src.  There is no associated data type once in memmove().
dest and src are pointers to "nothing" (i.e., raw
addresses for memory) due to the parameter type conversion.

char a[10];

 memmove(a[2],a[5],5);

a[2] and a[5] "reduce" to pointers to char.
These pointers to char are converted to
pointers to void to be passed into memmove().
All type information is lost at that point.
It does not propagate as you've indicated in
your article.  In memmove(), there is no type
association, no object association, etc for
dest and src.

HTH,


Rod Pemberton

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OT: One of Anton's papers makes Hacker News Paul Rubin <no.email@nospam.invalid> - 2016-03-03 16:24 -0800
  Re: OT: One of Anton's papers makes Hacker News Julian Fondren <julian.fondren@gmail.com> - 2016-03-03 21:06 -0800
    Re: OT: One of Anton's papers makes Hacker News Ron Aaron <rambamist@gmail.com> - 2016-03-04 07:18 +0200
    Re: OT: One of Anton's papers makes Hacker News Paul Rubin <no.email@nospam.invalid> - 2016-03-03 21:33 -0800
      Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-04 17:52 +0000
    Re: OT: One of Anton's papers makes Hacker News Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-04 12:32 +0000
      Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-04 18:20 +0000
        Re: OT: One of Anton's papers makes Hacker News Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-05 02:23 +0000
          Re: OT: One of Anton's papers makes Hacker News hughaguilar96@gmail.com - 2016-03-04 19:06 -0800
            Re: OT: One of Anton's papers makes Hacker News Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-03-05 20:32 -0500
          Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-06 11:28 +0000
            Re: OT: One of Anton's papers makes Hacker News Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-06 18:02 +0000
              Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-06 23:55 +0000
            Re: OT: One of Anton's papers makes Hacker News hughaguilar96@gmail.com - 2016-03-06 14:48 -0800
              Re: OT: One of Anton's papers makes Hacker News Julian Fondren <julian.fondren@gmail.com> - 2016-03-07 03:36 -0800
            Re: OT: One of Anton's papers makes Hacker News Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-03-07 19:19 -0500
              Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-12 17:40 +0000
        Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-05 03:35 -0600
          Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-05 13:37 +0000
            Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-05 15:42 -0600
              Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-06 00:50 +0000
                Re: OT: One of Anton's papers makes Hacker News Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-03-05 20:33 -0500
                Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-06 02:01 +0000
                Re: OT: One of Anton's papers makes Hacker News Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-06 11:57 +0000
                Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-07 07:35 +0000
                Re: OT: One of Anton's papers makes Hacker News Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-07 12:40 +0000
                Re: OT: One of Anton's papers makes Hacker News Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-03-07 19:20 -0500
                Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-08 00:49 +0000
                Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-06 02:20 -0600
                Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-07 00:35 +0000
                Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-07 02:53 -0600
                Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-07 16:07 +0000
                Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-08 05:17 -0600
                Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-08 22:01 +0000
                Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-09 03:14 -0600
                Re: OT: One of Anton's papers makes Hacker News Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-09 11:17 +0000
                Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-09 23:58 +0000
                Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-10 04:45 -0600
                Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-10 11:39 +0000
                Re: OT: One of Anton's papers makes Hacker News Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-10 13:29 +0000
                Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-12 16:02 +0000
                Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-10 08:22 -0600
                Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-12 15:49 +0000
                Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-12 13:35 -0600
                Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-10 21:58 +0000
                Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-11 06:11 -0600
                Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-12 00:05 +0000
                Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-12 04:23 -0600
                Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-12 12:05 +0000
                Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-12 08:36 -0600
                Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-12 16:57 +0000
                Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-12 13:44 -0600
                Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-12 14:29 +0000
                Re: OT: One of Anton's papers makes Hacker News "Elizabeth D. Rather" <erather@forth.com> - 2016-03-11 15:02 -1000
                Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-12 16:20 +0000
                Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-12 13:53 -0600
                Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-06 13:02 +0000
          Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-06 11:52 +0000
            Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-06 12:42 -0600
              Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-06 13:12 -0600
  Re: OT: One of Anton's papers makes Hacker News Ron Aaron <rambamist@gmail.com> - 2016-03-04 07:20 +0200
  Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-04 17:37 +0000
  Re: OT: One of Anton's papers makes Hacker News Julian Fondren <julian.fondren@gmail.com> - 2016-03-04 11:23 -0800
    Re: OT: One of Anton's papers makes Hacker News Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-03-09 03:24 -0600
  Re: OT: One of Anton's papers makes Hacker News Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-03-04 21:01 -0500
    Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-05 13:51 +0000
      Re: OT: One of Anton's papers makes Hacker News Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-03-05 19:43 -0500
        Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-06 01:45 +0000
          Re: OT: One of Anton's papers makes Hacker News Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-03-07 19:19 -0500
            Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-12 17:24 +0000
              Re: OT: One of Anton's papers makes Hacker News Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-13 12:27 +0000
                Re: OT: One of Anton's papers makes Hacker News raltbos@xs4all.nl (Richard Bos) - 2016-03-13 13:50 +0000
                Re: OT: One of Anton's papers makes Hacker News Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-13 19:52 +0000
                Re: OT: One of Anton's papers makes Hacker News Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-03-13 16:08 -0400
                Re: OT: One of Anton's papers makes Hacker News Keith Thompson <kst-u@mib.org> - 2016-03-13 13:40 -0700
                Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-14 00:41 +0000
                Re: OT: One of Anton's papers makes Hacker News Keith Thompson <kst-u@mib.org> - 2016-03-13 18:23 -0700
                Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-14 02:59 +0000
                Re: OT: One of Anton's papers makes Hacker News Keith Thompson <kst-u@mib.org> - 2016-03-13 20:29 -0700
                Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-14 22:44 +0000
                Re: OT: One of Anton's papers makes Hacker News Keith Thompson <kst-u@mib.org> - 2016-03-14 16:23 -0700
                Re: OT: One of Anton's papers makes Hacker News Jan Coombs <jenfhaomndgfwutc@murmic.plus.com> - 2016-03-14 23:55 +0000
                Re: OT: One of Anton's papers makes Hacker News Keith Thompson <kst-u@mib.org> - 2016-03-14 17:19 -0700
                Re: OT: One of Anton's papers makes Hacker News Robert Wessel <robertwessel2@yahoo.com> - 2016-03-14 19:26 -0500
                Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-15 00:48 +0000
                Re: OT: One of Anton's papers makes Hacker News Keith Thompson <kst-u@mib.org> - 2016-03-14 22:30 -0700
                Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-15 07:23 +0000
                Re: OT: One of Anton's papers makes Hacker News Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-15 10:09 +0000
                Re: OT: One of Anton's papers makes Hacker News Keith Thompson <kst-u@mib.org> - 2016-03-15 08:56 -0700
                Re: OT: One of Anton's papers makes Hacker News Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-15 19:33 +0000
                Re: OT: One of Anton's papers makes Hacker News Rosario19 <Ros@invalid.invalid> - 2016-03-17 09:46 +0100
                Re: OT: One of Anton's papers makes Hacker News Jerry Stuckle <jstucklex@attglobal.net> - 2016-03-17 09:37 -0400
                Re: OT: One of Anton's papers makes Hacker News Rosario19 <Ros@invalid.invalid> - 2016-03-17 18:40 +0100
                Re: OT: One of Anton's papers makes Hacker News Jerry Stuckle <jstucklex@attglobal.net> - 2016-03-17 13:53 -0400
                Re: OT: One of Anton's papers makes Hacker News invalid <address@is.invalid> - 2016-03-17 18:00 +0000
                Re: OT: One of Anton's papers makes Hacker News Rosario19 <Ros@invalid.invalid> - 2016-03-17 18:37 +0100
                Re: OT: One of Anton's papers makes Hacker News Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-18 14:36 +0000
                Re: OT: One of Anton's papers makes Hacker News David Brown <david.brown@hesbynett.no> - 2016-03-14 09:17 +0100
                Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-14 22:56 +0000
                Re: OT: One of Anton's papers makes Hacker News Robert Wessel <robertwessel2@yahoo.com> - 2016-03-14 20:00 -0500
                Re: OT: One of Anton's papers makes Hacker News David Brown <david.brown@hesbynett.no> - 2016-03-15 11:22 +0100
                Re: OT: One of Anton's papers makes Hacker News raltbos@xs4all.nl (Richard Bos) - 2016-03-14 22:38 +0000
                Re: OT: One of Anton's papers makes Hacker News Randy Howard <rhoward.mx@EverybodyUsesIt.com> - 2016-03-14 01:40 -0500
    Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-06 11:00 +0000
      Re: OT: One of Anton's papers makes Hacker News Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-03-07 19:19 -0500
        Re: OT: One of Anton's papers makes Hacker News Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-08 01:02 +0000
  Re: OT: One of Anton's papers makes Hacker News Julian Fondren <ayrnieu@gmail.com> - 2016-03-14 07:29 -0700
    Re: OT: One of Anton's papers makes Hacker News anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-18 17:45 +0000

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