linux-kernel - Re: [RFC][PATCH] Update -Wattribute-alias for gcc9

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Date:   Fri, 25 Jan 2019 12:24:49 +0000
From:   Bernd Edlinger <bernd.edlinger@...mail.de>
To:     Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        Arnd Bergmann <arnd@...db.de>
CC:     Laura Abbott <labbott@...hat.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Martin Sebor <msebor@...il.com>
Subject: Re: [RFC][PATCH] Update -Wattribute-alias for gcc9

On 1/25/19 12:39 PM, Miguel Ojeda wrote:
> On Fri, Jan 25, 2019 at 11:58 AM Arnd Bergmann <arnd@...db.de> wrote:
>>
>> On Fri, Jan 25, 2019 at 11:43 AM Laura Abbott <labbott@...hat.com> 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 <labbott@...hat.com>
>>> ---
>>> 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.


Bernd.