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Re: Autoconf manual's coverage of signed integer overflow & portability
From: |
Paul Eggert |
Subject: |
Re: Autoconf manual's coverage of signed integer overflow & portability |
Date: |
Tue, 02 Jan 2007 22:45:27 -0800 |
User-agent: |
Gnus/5.1008 (Gnus v5.10.8) Emacs/21.4 (gnu/linux) |
Andrew Pinski <address@hidden> writes:
> Let me make the point that signed overflow has been undefined since
> before the C standard was finialized and in fact there is a nice
> paper/book called "C Traps and Pitfalls[2]" which mentions all of this
> back in 1988.
C Traps and Pitfalls, like K&Rv2, is derived from a draft of the C89
standard and was intended to match the final C89 standard closely. It
is therefore not a reliable source of information about traditional C.
K&Rv1 is a better source, and as David Daney reports in
<http://gcc.gnu.org/ml/gcc/2006-12/msg00948.html>
it said that integer overflow handling was machine-dependent
and that all existing implementations ignored overflows.
This corresponds to existing practice at the time,
which was that signed overflow wrapped; but clearly
there was an attempt to allow other implementations.
Compiler writers have been trying to drag C users away from C's
traditional wrapping semantics ever since C89 came out, but they
haven't been all that succesful yet.
- Re: Autoconf manual's coverage of signed integer overflow & portability, (continued)
- Re: Autoconf manual's coverage of signed integer overflow & portability, Gabriel Dos Reis, 2007/01/03
- Re: Autoconf manual's coverage of signed integer overflow & portability, Paul Eggert, 2007/01/03
- Re: Autoconf manual's coverage of signed integer overflow & portability, Andrew Pinski, 2007/01/03
- Re: Autoconf manual's coverage of signed integer overflow & portability, Paul Eggert, 2007/01/03
- Re: Autoconf manual's coverage of signed integer overflow & portability, Andrew Haley, 2007/01/03
- RE: Autoconf manual's coverage of signed integer overflow & portability, Meissner, Michael, 2007/01/13
- Re: Autoconf manual's coverage of signed integer overflow & portability, Gabriel Dos Reis, 2007/01/03
Re: Autoconf manual's coverage of signed integer overflow & portability, Robert Dewar, 2007/01/02
Re: Autoconf manual's coverage of signed integer overflow & portability, Russell Shaw, 2007/01/02
Re: Autoconf manual's coverage of signed integer overflow & portability, Andrew Pinski, 2007/01/02