From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 5579 invoked by alias); 16 Dec 2015 00:21:57 -0000 Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org Received: (qmail 5557 invoked by uid 89); 16 Dec 2015 00:21:56 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Wed, 16 Dec 2015 00:21:55 +0000 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id A4C2991595; Wed, 16 Dec 2015 00:21:54 +0000 (UTC) Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id tBG0Lpk3012373; Tue, 15 Dec 2015 19:21:53 -0500 Message-ID: <5670AE9F.3060308@redhat.com> Date: Wed, 16 Dec 2015 00:21:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Simon Marchi , "Jose E. Marchesi" CC: Yao Qi , "gdb@sourceware.org" Subject: Re: C++ conversion status update References: <565460FB.6070103@redhat.com> <86zixdnlfg.fsf@gmail.com> <566F13D4.9000900@redhat.com> <877fkglytf.fsf@oracle.com> <5670AE0A.20201@redhat.com> In-Reply-To: <5670AE0A.20201@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2015-12/txt/msg00016.txt.bz2 Forgot to mention that this compiles down to the same as offsetof at -O2. On 12/16/2015 12:19 AM, Pedro Alves wrote: > diff --git a/gdb/common/vec.h b/gdb/common/vec.h > index 6189283..a188b02 100644 > --- a/gdb/common/vec.h > +++ b/gdb/common/vec.h > @@ -437,13 +437,23 @@ DEF_VEC_FUNC_O(T) \ > DEF_VEC_ALLOC_FUNC_O(T) \ > struct vec_swallow_trailing_semi > > +/* Avoid offsetof (or its usual C implementation) as it triggers > + -Winvalid-offsetof warnings with enum_flags types with G++ <= 4.4, > + even though those types are memcpyable. This requires allocating a > + dummy local VEC in all routines that use this, but that has the > + advantage that it only works if T is default constructible, which > + is exactly a check we want, to keep C compatibility. */ > +#define vec_offset(T, VPTR) ((size_t) ((char *) &(VPTR)->vec - (char *) VPTR)) Thanks, Pedro Alves