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Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."

From: Bernd Schmidt <bernds_cb1 at t-online dot de>
To: Paul Eggert <eggert at CS dot UCLA dot EDU>
Cc: Richard Guenther <richard dot guenther at gmail dot com>, autoconf-patches at gnu dot org, bug-gnulib at gnu dot org, gcc at gcc dot gnu dot org
Date: Sat, 30 Dec 2006 12:09:27 +0100
Subject: Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
References: <87fybbyq27.fsf@penguin.cs.ucla.edu> <20061220123349.GE7947@iam.uni-bonn.de> <emc3jc$eap$1@sea.gmane.org> <87mz57xjlf.fsf@penguin.cs.ucla.edu> <m3odpmsnlc.fsf@localhost.localdomain> <878xgqmlvs.fsf@penguin.cs.ucla.edu> <84fc9c000612291343x46a07cf9u49405b2378cc5ce0@mail.gmail.com> <87sleyl11p.fsf@penguin.cs.ucla.edu>

Paul Eggert wrote:

"Richard Guenther" <richard.guenther@gmail.com> writes:

Authors of the affected programs should adjust their makefiles


That is what the proposed patch is for.  It gives a way for
developers to adjust their makefiles.

A developer of portable software cannot simply put something
like this into a makefile:

CFLAGS = -g -O2 -fwrapv

as -fwrapv won't work with most other compilers.  So the
developer needs some Autoconfish help anyway, to address the
problem.  The proposed help is only rudimentary, but it does
adjust makefiles to address the issue, and it's better than
nothing.  Further improvements would of course be welcome.

So rather than changing the default to -fwrapv for all programs, which I would find most unwelcome, how about adding a macro AC_THIS_PROGRAM_IS_BROKEN_AND_THE_MAINTAINER_DOESNT_CARE which could add -fwrapv and maybe -fno-strict-aliasing if the compiler supports them? Then anyone who knows their program is affected, or is just worried that it might be, could add that macro to their configure.in.

Bernd

Follow-Ups:
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
  - From: Kaveh R. GHAZI

References:
- 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: Richard Guenther
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
  - From: Paul Eggert

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