DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 65AEC8E66A
Subject: Re: [PATCH resent] uapi libc compat: allow non-glibc to opt out of
 uapi definitions
To: "Carlos O'Donell" <carlos@redhat.com>, linux-kernel@vger.kernel.org,
        "David S. Miller" <davem@davemloft.net>, linux-api@vger.kernel.org,
        musl@lists.openwall.com, Rich Felker <dalias@aerifal.cx>
References: <20161111120820.GA435@nyan>
 <a360ec42-33ca-5e89-3d70-3b1c9a011c7f@redhat.com>
 <20170309001435.GJ2082@port70.net>
From: Florian Weimer <fweimer@redhat.com>
Message-ID: <1d9ab212-6c80-f7fa-4be5-87b567ada949@redhat.com>
Date: Tue, 25 Apr 2017 15:22:00 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.0
MIME-Version: 1.0
In-Reply-To: <20170309001435.GJ2082@port70.net>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 895
Lines: 21

On 03/09/2017 01:14 AM, Szabolcs Nagy wrote:
> the other way (linux header included first) is
> problematic because linux headers don't follow
> all the standards the libc follows, they violate
> namespace rules in their struct definitions, so
> the libc definitions are necessarily incompatible
> with them and thus different translation units can
> end up refering to the same object through
> incompatible types which is undefined.
> (even if the abi matches and thus works across
> the syscall interface, a sufficiently smart
> toolchain can break such code at link time,
> and since the libc itself uses its own definitons
> that's what user code should use too).

I don't think this is relevant in this context.  LTO implementations 
have to deal with this already.  For glibc's sake alone, it must be 
supported to link together code using differing feature test macros.

Thanks,
Florian