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Re: Autoconf manual's coverage of signed integer overflow & portability

From: Robert Dewar <dewar at adacore dot com>
To: Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>
Cc: eggert at cs dot ucla dot edu, autoconf-patches at gnu dot org, autoconf at gnu dot org, bug-autoconf at gnu dot org, bug-gnulib at gnu dot org, gcc at gcc dot gnu dot org
Date: Tue, 02 Jan 2007 22:04:03 -0500
Subject: Re: Autoconf manual's coverage of signed integer overflow & portability
References: <200612300047.kBU0lFwk014817@localhost.localdomain> <871wmht4ab.fsf@penguin.cs.ucla.edu> <10612302258.AA24598@vlsi1.ultra.nyu.edu> <87lkkosz1n.fsf@penguin.cs.ucla.edu> <45970416.80407@adacore.com> <8764bssikm.fsf@penguin.cs.ucla.edu> <571f6b510612310047r3b7ef9acl4a0ab082e88e17a3@mail.gmail.com> <87bqlkmm3r.fsf@penguin.cs.ucla.edu> <4aca3dc20612310641n78e8898euf1c003444e2303eb@mail.gmail.com> <84fc9c000612310645h67066c70vf9eb11af74b639a7@mail.gmail.com> <4aca3dc20612311613r2992db50o851c7d73603b42ef@mail.gmail.com> <87r6ufley1.fsf@penguin.cs.ucla.edu> <m3zm93sc88.fsf@localhost.localdomain> <87zm933wmd.fsf@penguin.cs.ucla.edu> <m3irfqsnge.fsf@localhost.localdomain> <87y7omk4ox.fsf@penguin.cs.ucla.edu> <m3vejqqgq2.fsf@localhost.localdomain> <87ps9x80a8.fsf_-_@penguin.cs.ucla.edu> <10701030001.AA11515@vlsi1.ultra.nyu.edu>

Richard Kenner wrote:

A few comments:

Many portable C programs assume that signed integer overflow wraps around
reliably using two's complement arithmetic.


I'd replace "portable C programs" with "widely-used C programs".  The normal
use of "portable" means that it conforms to the standard.


Actually the use of portable here is quite appropriate, it emphasizes
that such programs in general are pretty portable *despite* the fact
that they do not conform to the standard.

References:
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
  - From: Daniel Berlin
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
  - From: Paul Eggert
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
  - From: Ian Lance Taylor
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
  - From: Paul Eggert
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
  - From: Ian Lance Taylor
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
  - From: Paul Eggert
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
  - From: Ian Lance Taylor
- Autoconf manual's coverage of signed integer overflow & portability
  - From: Paul Eggert
- Re: Autoconf manual's coverage of signed integer overflow & portability
  - From: Richard Kenner

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