Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Message-ID: <48b8af08170fb896c12cc4e3eae7501b4fa4181d.camel@opteya.com>
From:   Yann Droneaud <ydroneaud@opteya.com>
To:     Greg KH <greg@kroah.com>, David Howells <dhowells@redhat.com>
Cc:     linux-api@vger.kernel.org, linux-kbuild@vger.kernel.org,
        Michal Marek <michal.lkml@markovi.net>,
        dri-devel@lists.freedesktop.org,
        virtualization@lists.linux-foundation.org,
        keyrings@vger.kernel.org, David Airlie <airlied@linux.ie>,
        linux-nilfs@vger.kernel.org, linux-nvdimm@lists.01.org,
        "Michael S. Tsirkin" <mst@redhat.com>, codalist@coda.cs.cmu.edu,
        coda@cs.cmu.edu, coreteam@netfilter.org,
        Rob Clark <robdclark@gmail.com>, linux-arm-msm@vger.kernel.org,
        Kent Overstreet <kent.overstreet@gmail.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Takashi Iwai <tiwai@suse.com>, linux-bcache@vger.kernel.org,
        Coly Li <colyli@suse.de>, Jaroslav Kysela <perex@perex.cz>,
        Jan Harkes <jaharkes@cs.cmu.edu>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>,
        Jason Wang <jasowang@redhat.com>,
        Mat Martineau <mathew.j.martineau@linux.intel.com>,
        netfilter-devel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        moderated for non-subscribers <alsa-devel@alsa-project.org>,
        freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org
Date:   Thu, 06 Sep 2018 09:12:58 +0200
In-Reply-To: <a1efae8d26cc5b73b180e9521d6b62590c55aa86.camel@opteya.com>
References: <153616286704.23468.584491117180383924.stgit@warthog.procyon.org.uk>
         <20180905165552.GB25206@kroah.com>
         <a1efae8d26cc5b73b180e9521d6b62590c55aa86.camel@opteya.com>
Organization: OPTEYA
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 8bit
Subject: Re: [RFC] UAPI: Check headers by compiling all together as C++
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Le mercredi 05 septembre 2018 à 19:33 +0200, Yann Droneaud a écrit :
> Le mercredi 05 septembre 2018 à 18:55 +0200, Greg KH a écrit :
> > On Wed, Sep 05, 2018 at 04:54:27PM +0100, David Howells wrote:
> > > 
> > > Here's a set of patches that inserts a step into the build
> > > process to make
> > > sure that the UAPI headers can all be built together with C++ (if
> > > the
> > > compiler being used supports C++).  All but the final patch
> > > perform fixups,
> > > including:
> > 
> > Wait, why do we care?  What has recently changed to start to
> > directly
> > import kernel uapi files into C++ code?
> > 
> > And if userspace wants to do this, can't they do the C namespace
> > trick
> > themselves when they do the import?  That must be how they are
> > doing it
> > today, right?
> > 
> 
> They can't.
> 
> 
> Adding extern "C" { } doesn't magically make "class" a non keyword.
> Even if it was the case, writing C++ code using whatever->class would
> probably broke because class is a keyword in C++.
> 

For the record, libX11 has to handle the kink pf issue with C++
keyword:


https://gitlab.freedesktop.org/xorg/lib/libx11/blob/733f64bfeb311c1d040b2f751bfdef9c9d0f89ef/include/X11/Xlib.h#L227

typedef struct {
	XExtData *ext_data;	/* hook for extension to hang data */
	VisualID visualid;	/* visual id of this visual */
#if defined(__cplusplus) || defined(c_plusplus)
	int c_class;		/* C++ class of screen (monochrome, etc.) */
#else
	int class;		/* class of screen (monochrome, etc.) */
#endif
	unsigned long red_mask, green_mask, blue_mask;	/* mask values */
	int bits_per_rgb;	/* log base 2 of distinct color values */
	int map_entries;	/* color map entries */
} Visual;


Regards.

-- 
Yann Droneaud
OPTEYA