linux-kernel - RE: #pragma once (was Re: incoming)

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Message-ID: <a941107b94f74be0914a359b144ec134@AcuMS.aculab.com>
Date:   Mon, 1 Mar 2021 16:52:16 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Alexey Dobriyan' <adobriyan@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
CC:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: RE: #pragma once (was Re: incoming)

From: Alexey Dobriyan <adobriyan@...il.com>
> Sent: 26 February 2021 23:02
> 
> On Fri, Feb 26, 2021 at 01:53:48PM -0800, Linus Torvalds wrote:
> > On Fri, Feb 26, 2021 at 12:17 PM Alexey Dobriyan <adobriyan@...il.com> wrote:
> > >
> > > I want to sent treewide "#pragma once" conversion:
> >
> > Are there *any* advantages to it?
> >
> > It's non-standard,
> 
> It is effectively standard:
> https://en.wikipedia.org/wiki/Pragma_once#Portability

At the top of the page....

In the C and C++ programming languages, pragma once is a non-standard but widely supported

So non-standard :-)

And #pragma is ugly...

There are also times when an include guard has to be set in order to stop
a problematic inner file being included.
Perhaps only during hacking, but it is useful.

	David

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