From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gdb-return-35920-listarch-gdb=sources.redhat.com@sourceware.org>
Received: (qmail 29744 invoked by alias); 10 Oct 2009 18:24:07 -0000
Received: (qmail 29731 invoked by uid 22791); 10 Oct 2009 18:24:06 -0000
X-SWARE-Spam-Status: No, hits=-2.5 required=5.0 	tests=AWL,BAYES_00,SPF_PASS
X-Spam-Check-By: sourceware.org
Received: from mail.codesourcery.com (HELO mail.codesourcery.com) (38.113.113.100)     by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Sat, 10 Oct 2009 18:24:01 +0000
Received: (qmail 22671 invoked from network); 10 Oct 2009 18:24:00 -0000
Received: from unknown (HELO orlando) (pedro@127.0.0.2)   by mail.codesourcery.com with ESMTPA; 10 Oct 2009 18:24:00 -0000
From: Pedro Alves <pedro@codesourcery.com>
To: gdb@sourceware.org,  Eli Zaretskii <eliz@gnu.org>
Subject: Re: A strange gcc behavior, and an argument against -Wno-unused
Date: Sat, 10 Oct 2009 18:24:00 -0000
User-Agent: KMail/1.9.10
Cc: dave.korn.cygwin@googlemail.com,  msnyder@vmware.com
References: <4ACFD8B7.4090902@vmware.com> <200910101745.27358.pedro@codesourcery.com> <83iqenjf1f.fsf@gnu.org>
In-Reply-To: <83iqenjf1f.fsf@gnu.org>
MIME-Version: 1.0
Content-Type: text/plain;   charset="us-ascii"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <200910101924.12313.pedro@codesourcery.com>
X-IsSubscribed: yes
Mailing-List: contact gdb-help@sourceware.org; run by ezmlm
Precedence: bulk
List-Id: <gdb.sourceware.org>
List-Subscribe: <mailto:gdb-subscribe@sourceware.org>
List-Archive: <http://sourceware.org/ml/gdb/>
List-Post: <mailto:gdb@sourceware.org>
List-Help: <mailto:gdb-help@sourceware.org>, <http://sourceware.org/ml/#faqs>
Sender: gdb-owner@sourceware.org
X-SW-Source: 2009-10/txt/msg00193.txt.bz2

On Saturday 10 October 2009 19:10:36, Eli Zaretskii wrpte:

> What version of GCC introduced this switch?

If you're worried about breaking the build with older
gcc's, note that gdb/configure.ac filters out -W options
that gcc doesn't recognize.

if test "x${build_warnings}" != x -a "x$GCC" = xyes
then
    AC_MSG_CHECKING(compiler warning flags)
    # Separate out the -Werror flag as some files just cannot be
    # compiled with it enabled.
    for w in ${build_warnings}; do
	case $w in
	-Werr*) WERROR_CFLAGS=-Werror ;;
	*) # Check that GCC accepts it
	    saved_CFLAGS="$CFLAGS"
	    CFLAGS="$CFLAGS $w"
	    AC_TRY_COMPILE([],[],WARN_CFLAGS="${WARN_CFLAGS} $w",)
	    CFLAGS="$saved_CFLAGS"
	esac
    done
    AC_MSG_RESULT(${WARN_CFLAGS} ${WERROR_CFLAGS})
fi

That said, I don't know when the switch was introduced
in gcc.

-- 
Pedro Alves