Re: what is defined, was for or against equality

From	Thomas Koenig <tkoenig@netcologne.de>
Newsgroups	comp.compilers
Subject	Re: what is defined, was for or against equality
Date	2022-01-06 16:43 +0000
Organization	news.netcologne.de
Message-ID	<22-01-020@comp.compilers> (permalink)
References	<17d70d74-1cf1-cc41-6b38-c0b307aeb35a@gkc.org.uk> <22-01-016@comp.compilers> <22-01-018@comp.compilers>

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David Brown <david.brown@hesbynett.no> schrieb:

> There is no need to memorize undefined behaviours for a language -
> indeed, such a thing is impossible since everything not defined by a
> language standard is, by definition, undefined behaviour. (C and C++
> are not special here - the unusual thing is just that their standards
> say this explicitly.)

This is a rather C-centric view of things.  The Fortran standard
uses a different model.

There are constraints, which are numbered.  Any violation of such
a constraint needs to be reported by the compiler ("processor",
in Fortran parlance).  If it fails to do so, this is a bug in
the compiler.

There are also phrases which have "shall" or "shall not".  If this
is violated, this is an error in the program.  Catching such a
violation is a good thing from quality of implementation standpoint,
but is not required.  Many run-time errors such as array overruns
fall into this category.

[...]

> The real challenge from big languages and big standard libraries is not
> /writing/ code, it is /reading/ it.  It doesn't really matter if a C
> programmer, when writing some code, does not know what the syntax "void
> foo(int a[static 10]);"  means.  (Most C programmers don't know it, and
> never miss it.)  But it can be a problem if they have to read and
> understand code that uses something they don't know.

Agreed.

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Re: for or against equality, was Why are ambiguous grammars usually a bad idea? Martin Ward <martin@gkc.org.uk> - 2022-01-05 10:25 +0000
  Re: for or against equality, was Why are ambiguous grammars usually a bad idea? David Brown <david.brown@hesbynett.no> - 2022-01-06 09:11 +0100
    Re: what is defined, was for or against equality Thomas Koenig <tkoenig@netcologne.de> - 2022-01-06 16:43 +0000
      Re: what is defined, was for or against equality David Brown <david.brown@hesbynett.no> - 2022-01-07 12:06 +0100
      Re: what is defined, was for or against equality Spiros Bousbouras <spibou@gmail.com> - 2022-01-07 13:21 +0000
        Re: what is defined, was for or against equality Thomas Koenig <tkoenig@netcologne.de> - 2022-01-08 09:31 +0000
          Re: what is defined, was for or against equality Spiros Bousbouras <spibou@gmail.com> - 2022-01-08 22:28 +0000
            Re: what is defined, was for or against equality Thomas Koenig <tkoenig@netcologne.de> - 2022-01-09 00:09 +0000
              Re: what is defined, was for or against equality Spiros Bousbouras <spibou@gmail.com> - 2022-01-09 21:30 +0000
          Re: what is defined, was for or against equality David Brown <david.brown@hesbynett.no> - 2022-01-09 23:00 +0100
            Re: what is defined, was for or against equality Thomas Koenig <tkoenig@netcologne.de> - 2022-01-10 12:04 +0000
              Re: what is defined, was for or against equality David Brown <david.brown@hesbynett.no> - 2022-01-11 18:16 +0100
                Re: what is defined, was for or against equality Kaz Kylheku <480-992-1380@kylheku.com> - 2022-01-11 19:19 +0000
                Re: what is defined, was for or against equality gah4 <gah4@u.washington.edu> - 2022-01-11 14:18 -0800
                Re: what is defined, was for or against equality Thomas Koenig <tkoenig@netcologne.de> - 2022-01-12 19:02 +0000
                Re: what is defined, was for or against equality David Brown <david.brown@hesbynett.no> - 2022-01-13 08:24 +0100
                Re: what is defined, was for or against equality Thomas Koenig <tkoenig@netcologne.de> - 2022-01-13 11:17 +0000
          Re: what is defined, was for or against equality gah4 <gah4@u.washington.edu> - 2022-01-10 16:58 -0800
    Re: for or against equality, was Why are ambiguous grammars usually a bad idea? Robert Prins <robert@prino.org> - 2022-01-06 19:07 +0000
    Undefined behaviour, was: for or against equality Martin Ward <martin@gkc.org.uk> - 2022-01-07 14:02 +0000
      Re: Undefined behaviour, was: for or against equality Spiros Bousbouras <spibou@gmail.com> - 2022-01-08 03:41 +0000
    Re: Undefined behaviour, was: for or against equality David Brown <david.brown@hesbynett.no> - 2022-01-07 15:56 +0100
      Re: Undefined behaviour, was: for or against equality anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2022-01-08 17:52 +0000
        Re: Undefined behaviour, was: for or against equality David Brown <david.brown@hesbynett.no> - 2022-01-09 23:53 +0100
        Re: Undefined behaviour, was: for or against equality Kaz Kylheku <480-992-1380@kylheku.com> - 2022-01-11 16:55 +0000
          Re: Undefined behaviour, was: for or against equality George Neuner <gneuner2@comcast.net> - 2022-01-11 22:01 -0500

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