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Groups > comp.lang.forth > #56947

Re: LLVM and Forth

From Paul Rubin <no.email@nospam.invalid>
Newsgroups comp.lang.forth
Subject Re: LLVM and Forth
Date 2017-04-09 14:07 -0700
Organization A noiseless patient Spider
Message-ID <87r3118f3q.fsf@nightsong.com> (permalink)
References (10 earlier) <cf7e8f98-9839-4faa-b734-8e0ad9f8d1d1@googlegroups.com> <IAqFA.243119$0L.131983@fx12.am4> <20170407033309.1b6469f0@_> <b8b4e62a-6b68-4149-9178-4ab42eda105c@googlegroups.com> <20170409133515.2b871c2c@_>

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Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> writes:
> C explicitly allows dereferencing one past the end of an array.  As
> stated previously, this requirement is in ALL of the C specifications.

I don't think that is right.  My understanding was you're allowed to set
a pointer to point one past the end of the array, but you're not allowed
to dereference that pointer.

http://stackoverflow.com/questions/988158/take-the-address-of-a-one-past-the-end-array-element-via-subscript-legal-by-the

discusses this at some length.

> Accessing one beyond is required to check for a nul character.  E.g.,
> while(*str++); /* find end-of-string *//* This is not UB */

The nul character is supposed to be within the array, not past it.
After the exit from that loop, str points one past the end of the array,
which is not UB, since you don't actually dereference it.  Dereferencing
it would be UB according to everything I remember.

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LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-01 06:36 -0700
  Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-01 14:57 +0000
    Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-01 11:55 -0700
      Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-02 15:24 +0000
  Re: LLVM and Forth rickman <gnuarm@gmail.com> - 2017-04-01 11:21 -0400
    Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-01 11:57 -0700
      Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-02 04:02 -0500
        Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-02 06:35 -0700
          Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-02 14:41 +0000
          Re: LLVM and Forth minforth@arcor.de - 2017-04-03 01:09 -0700
            Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-03 05:32 -0700
              Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-03 13:52 +0000
                Re: LLVM and Forth minforth@arcor.de - 2017-04-03 07:59 -0700
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-03 16:08 +0000
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-03 12:22 -0500
                Re: LLVM and Forth Paul Rubin <no.email@nospam.invalid> - 2017-04-03 20:10 -0700
                Re: LLVM and Forth minforth@arcor.de - 2017-04-03 22:19 -0700
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-04 16:12 +0200
                Re: LLVM and Forth Walter Banks <walter@bytecraft.com> - 2017-04-05 17:27 -0400
            Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-03 14:29 +0000
          Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-03 03:17 -0500
            Re: LLVM and Forth minforth@arcor.de - 2017-04-03 05:04 -0700
            Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-03 12:55 +0000
              Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-03 10:08 -0500
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-03 17:05 +0000
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-04 11:29 -0500
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-04 19:11 +0200
                Re: LLVM and Forth Paul Rubin <no.email@nospam.invalid> - 2017-04-04 21:29 -0700
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-05 15:01 +0000
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-05 18:42 +0100
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-06 04:01 -0500
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-06 18:48 +0000
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-06 18:42 -0700
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-07 04:02 -0500
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-08 21:18 -0700
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-08 22:43 +0000
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-08 20:54 -0700
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-09 14:53 +0000
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-10 00:38 +0000
                Re: LLVM and Forth James Kuyper <jameskuyper@verizon.net> - 2017-04-09 22:46 -0400
                Re: LLVM and Forth Robert Wessel <robertwessel2@yahoo.com> - 2017-04-09 22:27 -0500
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-10 12:36 +0000
                Re: LLVM and Forth Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-04-10 14:09 +0100
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-10 13:07 +0000
                Re: LLVM and Forth Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-04-10 16:18 +0100
                Re: LLVM and Forth "James R. Kuyper" <jameskuyper@verizon.net> - 2017-04-10 11:51 -0400
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-12 21:32 +0000
                Re: LLVM and Forth "James R. Kuyper" <jameskuyper@verizon.net> - 2017-04-12 18:29 -0400
                Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-12 15:29 -0700
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-13 02:55 +0200
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-10 18:38 -0700
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-10 11:54 -0500
                Re: LLVM and Forth Paul Rubin <no.email@nospam.invalid> - 2017-04-10 10:17 -0700
              Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-03 17:02 +0100
              Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-03 10:03 -0700
            Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-04 03:25 -0700
              Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-04 11:24 +0000
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-04 04:55 -0700
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-04 12:28 +0000
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-04 16:16 +0000
              Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-04 15:38 +0200
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-04 16:06 +0200
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-04 17:57 -0700
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-05 00:44 -0400
                Re: LLVM and Forth minforth@arcor.de - 2017-04-05 00:00 -0700
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-05 08:47 -0700
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-05 11:04 -0500
                Re: LLVM and Forth john <anon@example.com> - 2017-04-05 18:04 +0100
                Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-05 13:04 -0700
                Re: LLVM and Forth Paul Rubin <no.email@nospam.invalid> - 2017-04-05 18:20 -0700
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-05 20:14 -0700
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-06 12:33 +0000
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-06 10:49 -0700
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 18:55 +0100
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-06 20:41 +0000
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 21:47 +0100
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 21:56 +0100
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-06 23:59 -0400
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-06 17:10 -0700
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-07 03:33 -0400
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-08 22:48 +0000
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-09 15:06 -0400
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-08 22:45 -0700
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-09 14:27 +0000
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-09 21:26 -0700
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-09 13:35 -0400
                Re: LLVM and Forth Paul Rubin <no.email@nospam.invalid> - 2017-04-09 14:07 -0700
                Re: LLVM and Forth minforth@arcor.de - 2017-04-05 12:16 -0700
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-05 20:27 -0700
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-06 05:24 -0400
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-06 03:26 -0700
                Re: LLVM and Forth minforth@arcor.de - 2017-04-06 04:05 -0700
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-06 06:50 -0500
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-06 05:23 -0400
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-06 04:44 -0500
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 10:57 +0100
                Re: LLVM and Forth peter.m.falth@gmail.com - 2017-04-05 05:29 -0700
                Re: LLVM and Forth "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-04-14 02:04 +0000
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-15 14:03 +0200
                Re: LLVM and Forth "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-04-16 00:44 +0000
                Re: LLVM and Forth alex@rivadpm.com - 2017-04-16 05:53 -0700
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-16 15:43 +0000
                Re: LLVM and Forth "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-04-16 22:27 +0000
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-18 02:45 +0200
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-18 18:26 +0100
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-20 19:51 +0200
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-20 19:08 +0100
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-20 20:42 +0200
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-20 20:29 +0100
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-20 20:48 +0100
                Re: LLVM and Forth "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-04-21 11:49 +0000
          Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-03 20:39 -0400
  Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-02 21:15 +0100
    Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-02 15:18 -0700
      Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-03 13:07 +0100
        Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-03 09:45 -0700
          Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-03 22:52 +0100
            Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-03 15:25 -0700
              Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 09:35 +0100
      Re: LLVM and Forth antispam@math.uni.wroc.pl - 2017-04-06 01:36 +0000
        Re: LLVM and Forth minforth@arcor.de - 2017-04-05 22:00 -0700
          Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 09:52 +0100
        Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-06 20:15 -0700
    Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-03 05:20 -0700
      Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-03 17:11 +0100
  Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 17:43 +0100
    Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-06 10:53 -0700

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