From: Josh Triplett <josh@joshtriplett.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Sam Ravnborg <sam@ravnborg.org>,
linux-kbuild <linux-kbuild@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Michal Marek <mmarek@suse.cz>,
Rashika Kheria <rashika.kheria@gmail.com>
Subject: Re: #pragma once?
Date: Tue, 7 Jan 2014 02:50:54 -0800 [thread overview]
Message-ID: <20140107105054.GB4891@leaf> (raw)
In-Reply-To: <CAMuHMdWPq4YgUoxE1GvQbsEJQu-wjhpra2fRDgkNfEZP0sqpVQ@mail.gmail.com>
On Tue, Jan 07, 2014 at 10:48:53AM +0100, Geert Uytterhoeven wrote:
> On Tue, Jan 7, 2014 at 6:55 AM, Sam Ravnborg <sam@ravnborg.org> wrote:
> > On Mon, Jan 06, 2014 at 12:47:07PM -0800, Josh Triplett wrote:
> >> [CCing build-system folks and others likely to know about potential
> >> issues.]
> >>
> >> Does anyone have any objection to the use of "#pragma once" instead of
> >> the usual #ifndef-#define-...-#endif include guard? GCC, LLVM/clang,
> >> and the latest Sparse all support either method just fine. (I added
> >> support to Sparse myself.) Both have equivalent performance. "#pragma
> >> once" is simpler, and avoids the possibility of a typo in the defined
> >> guard symbol.
> > For kernel headers no concern.
>
> Just being cautious:
>
> Do we know the minimum gcc version that supports #pragma once?
>From checking the manuals, it goes back to at least 2.95. Searching
suggests that versions before 3.4 have a few bugs in "#pragma once"
support, but that those bugs only apply to using #pragma once in
combination with precompiled headers, which doesn't apply to the kernel.
- Josh Triplett
next prev parent reply other threads:[~2014-01-07 10:51 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-06 20:47 #pragma once? Josh Triplett
2014-01-06 21:00 ` Andrew Morton
2014-01-06 21:09 ` Josh Triplett
2014-01-06 21:33 ` Theodore Ts'o
2014-01-06 21:50 ` Dave Jones
2014-01-07 5:55 ` Sam Ravnborg
2014-01-07 9:48 ` Geert Uytterhoeven
2014-01-07 10:09 ` Michal Marek
2014-01-07 10:38 ` Josh Triplett
2014-01-07 10:50 ` Josh Triplett [this message]
2014-01-12 16:14 ` Patrick Palka
2014-01-13 5:53 ` Josh Triplett
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