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[213.175.37.11]) by smtp.gmail.com with ESMTPSA id n15sm88633065wrt.21.2019.01.28.06.35.25 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Mon, 28 Jan 2019 06:35:25 -0800 (PST) Subject: Re: [RFC][PATCH] Update -Wattribute-alias for gcc9 To: Bernd Edlinger , Miguel Ojeda , Arnd Bergmann Cc: Masahiro Yamada , Linux Kernel Mailing List , Martin Sebor References: <20190125104353.2791-1-labbott@redhat.com> From: Laura Abbott Message-ID: <2ffaeb04-3d51-fe9b-84b7-e009cb1dffeb@redhat.com> Date: Mon, 28 Jan 2019 15:35:24 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/28/19 5:28 AM, Bernd Edlinger wrote: > On 1/25/19 1:24 PM, Bernd Edlinger wrote: >> On 1/25/19 12:39 PM, Miguel Ojeda wrote: >>> On Fri, Jan 25, 2019 at 11:58 AM Arnd Bergmann wrote: >>>> >>>> On Fri, Jan 25, 2019 at 11:43 AM Laura Abbott wrote: >>>>> >>>>> Commit bee20031772a ("disable -Wattribute-alias warning for >>>>> SYSCALL_DEFINEx()") disabled -Wattribute-alias with gcc8. >>>>> gcc9 changed the format of -Wattribute-alias to take a parameter. >>>>> This doesn't quite match with the existing disabling mechanism >>>>> so update for gcc9 to match with the default (-Wattribute-alias=1). >>>>> >>>>> Signed-off-by: Laura Abbott >>>>> --- >>>>> This is RFC because it feels ugly. I went ahead and did the obvious fixup >>>>> but it's worth discussing if we're going to end up with an explosion or >>>>> if there's a better way to handle this in one macro. >>>> >>>> Bernd Edlinger has sent a patch to gcc for this: >>>> https://gcc.gnu.org/ml/gcc-patches/2019-01/msg01120.html >>>> >>>> and Miguel Ojeda said he wanted to send a patch for it to the >>>> kernel as well, not sure if he wanted to take a different >>>> approach there, so adding both to Cc here. >>> >>> Thanks Arnd (I was working with Martin on the expanded >>> -Wmissing-attribute warnings, not on this, but thanks nevertheless :). >>> >>> Martin/Bernd: from the GCC mailing list I am not sure if we should >>> expect the old behavior to be maintained or not. >>> >> >> I believe it is not intentional to break the old syntax of the >> pragma. There will be new -Wattribute-alias=1 and -Wattribute-alias=2 >> and -Wattribute-alias is easy to retain as an alias for -Wattribute-alias=1. >> That is what my patch will do. >> > > Okay, I committed the -Wattribute-alias patch to gcc trunk, now > as https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=268336 . > So there will be no need for a workaround on your side. > > Also fixed a few false positive -Waddress-of-packed-member warnings with > https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=268118 and > https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=268337 . > > However there remain a lot of warnings from -Waddress-of-packed-member, > that look more or less valid, has anybody an idea how to handle > these? > > > Bernd. > Thanks, I'll keep an eye out when this lands in Fedora gcc. I think once everything lands it will be easier to work on the remaining -Waddress-of-packed-member. Laura